Peer Victimization of Children and Adolescents with Intellectual Disabilities : A Systematic Literature Review from 2000-2020

(1)

Peer Victimization of Children and

Adolescents with Intellectual

Disabilities

A Systematic Literature Review from 2000-2020

Nida Ammar Rehman

One year master thesis 15 credits Supervisor Interventions in Childhood Karin Bertills

Examinator

(2)

SCHOOL OF EDUCATION AND COMMUNICATION (HLK) Jönköping University

Master Thesis 15 credits Interventions in Childhood Spring Semester 2020

ABSTRACT

Author: Nida Ammar Rehman

Main title: Peer Victimization of Children and Adolescents with Intellectual Disabilities

Subtitle: A Systematic Literature Review from 2000-2020

Pages: 30

Background: Children and adolescents with intellectual disabilities are at increased risk for peer

victimization in schools. Due to the deficits in their social, cognitive, and adaptive skills, these children face greater challenges to stand up for themselves thus, facing continued victimization.

Aim: This systematic literature review sought to critically identify the existing literature on

pre-dictors and outcomes which are associated with peer victimization in children and adolescents with intellectual disabilities in a school environment using the Biopsychosocial model.

Method: To conduct this study, a systematic search procedure was formulated to retrieve

rele-vant scholarly articles from the chosen databases. Peer reviewed journals were searched to re-trieve articles from education, psychology, and social sciences, published in English language between years 2000-2020. Only studies with children and adolescents ages 6 - 21 years were considered. A total of eight articles with five cross-sectional, two cohort, and one case-control studies qualified to answer the research questions.

Results: Findings varied across the social and psychological aspects. Social predictors and

out-comes were found to be dominant for peer victimization. Internalizing Behaviour Disorders as a whole was identified as a psychological predictor with low self-esteem and depressive feelings as individual predictors and outcomes of peer victimization.

Conclusion: Children and adolescents with intellectual disabilities are vulnerable to peer

vic-timization due to deficits in disability characteristics. Exposure to peer vicvic-timization can pose serious consequences on their social and psychological well-being. Implications for future re-search and methodological limitations of this study are also discussed.

Keywords: peer victimization, intellectual disabilities, biopsychosocial model, school, chil-dren, adolescents Postal address Högskolan för lärande och kommunikation (HLK) Box 1026 551 11 JÖNKÖPING Street address Gjuterigatan 5 Telephone 036–101000 Fax 036162585

(3)

رظنم سپ روذعم ہناروشناد: ںوی رمعون روا ںوچب ےلاو ی م ںی م ںولوکسا ںی ذاب ہناشن ےک ںوورمع مہ ی ز اک ہدای ہرطخ ک نا ۔ےہ اتوہ ی ترشاعم ی ملع ، ی لوکنا روا ی حلاص ںوتی ک ےراسخ ےک ی ےک ےنوہ ےڑھک ےئل ےنپا وک ںوچب نا ، ےس ہجو ز ےئل ہدای ز ےس ہدای ، ےہ اتڑپ انرک انماس اک ںولکشم سج ک ی ےس ہجو ہی ہ ےتنب ہناشن لسلسم ںی ۔ دصقم ل ہزئاج اک بدا مظنم سا : ےنی م ںی ئاب وی اس لشوسوکی م لوحام ےک لوکسا ےئوہ ےترک لامعتسا وک لڈام ںی روذعم ہناروشناد ی م ںورمعون روا ںوچب ےلاو ںی ذاب ہناشن ےک ںورمع مہ ی پ قلعتم ےس شی رٹل ہدوجوم رپ جئاتن روا ئوگ رچی ک ی قنت یدی ہدناشن ی ک ےنرک ی ک ششوک ی ئگ ی ۔ ہقیرط ڈ ہدرک بختنم ، ےئل ےک داقعنا ےک ےعلاطم سا : اٹی ب سی ملع ہقلعتم ےس ی ماضم نی ک ی زاب تفای ا ےئل ےک کی رط اک شلات مظنم ہقی ک عضو راک ای گ ای لاس وک دئارج ۔اھت 2000 -2020 مرد ےک نای رگنا یزی م نابز ںی لاو ےنوہ عئاش ی لعت می ، سفن تای مس روا جا ی ماضم ےس مولع نی ک لصاح ےی گ ۓ فرص ۔ 6 ےس 21 ک لاس ی ےعلاطم ےک ںورمعون روا ںوچب ےک رمع ک روغ رپ ای گ ای عومجم ۔ ی ماضم ھٹآ رپ روط نی م نج ںی س سارک چناپ لنشکی ا روا ، ٹروہوک ود ، کی ک سی ڈٹسا لورٹنک ی لماش قحت وج ےھت قی د تاباوج ےک تلااوس ےک ےنی ۔ےوہ رارق لہا ےک جئاتن : ترشاعم ی سفن روا یتای تن ےک ںؤولہپ ےجی آ فلتخم ۓ لاو ےنوہ ھتاس ےک ہبترم مہ ۔ ی ز یتدای ترشاعم ےئل ےک ی پ شی اپ بلاغ رپ جئاتن وک وگ ای گ ای عومجم ۔ ی نوردنا رپ روط ی سفن یتای بارخ ی پ وک شی گ اناچہپ رپ روط ےک وگ ای م سج ںی دارفنا ی دامتعا دوخ مک رپ روط ی رتمک ساسحا روا ی پ وک شی زاب ہناشن روا وگ ی تن ےک ہجی ک لصاح رپ روط ےک ای گ ای ۔ ہلصیف روذعم : ی ک ےراصخ ےک ی روذعم ہناروشناد ےس ہجو ی ےک ہبترم مہ ےنپا ےلاو رمعون روا ےچب لماح ےک زاب ہناشن ی ہ ےتاجوہ راکش اک ںی ک نا فاشکنا اک راکش ےک ہبترم مہ ۔ ی ترشاعم ی سفن روا یتای گنس رپ دوبہب نی پ جئاتن ادی اتکسرک ک لبقتسم ۔ےہ ی قحت قی رط روا ہقی ک راک ی ےک دودح تارمضم ھب رپ ی خ ہلدابت لای ک ای گ ای ۔ےہ

(4)

1

List of Abbreviations

PV Peer Victimization ID Intellectual Disabilities

IBD(s) Internalizing Behaviour Disorder(s) ASD Autism Spectrum Disorder

(7)

4

1 Introduction

Children and adolescents with disabilites face more frequent victimization as compared to their peers without disabilities (Carter & Spencer, 2006; Cummings et al., 2006; Rose et al., 2011). Due to asymmetry in power and the imbalance of strength (Olweus, 1994), peer victimization is a commonly faced experience by most children during their school lives (Hoover et al., 1992). This form of abuse, whether seldom or repetitive, imprints and undermines the healthy devel-opment of the victimized (Graham & Juvonen, 1998; Olweus, 1991). However, despite the commonality and widespread international awareness of school-based peer victimization throughout the last few decades (Smith et al., 1999), its many harmful affects contributing to social and psychological distress encircling children and adolescents who are frequently bullied are still unknown. Children and youth with intellectual disabilities face accentuated victimization and vulnerabilities due to personal attributes of deficits in intellectual functioning, cognitive and adaptive skills, social adjustment skills, and atypical and impaired physical appearance and abilities (Glumbić & Žunić-Pavlović, 2010; Maiano et al., 2016). There are few studies that have focused explicitly on individuals with intellectual disabilities. This scarcity of research makes it essential to gain a clear understanding of what constitutes to the elevated risk and may add to the negative consequences of peer victimization on individuals with intellectual disabilities (Maiano et al., 2016). Since peer victimization is a contextual phenomenon, studying it in a school context would demand deeper knowledge of its correlates in social and psychological dimensions (Juvonen & Graham, 2001). The Biopsychosocial model provides a framework to study disability in a context. It demands to understand an individual’s position centered within the intertwined social and psychological aura (Engel, 1977). In light of the need to add further knowledge, a systematic literature review will be conducted to study the peer victimization experiences of children and adolescents with intel-lectual disabilities. This study will embark on factors which predict the risk of children and adolescents with intellectual disabilities to be victimized and on potential outcome factors of peer victimization in the context of school. The gathered findings will be presented with the help of the biopsychosocial model.

(8)

5

2 Theoretical Background

2.1 Disability

Disability in an individual is defined as a lasting impairment either physical or mental which hinders an individual’s ability to function in social interactions, communication and/or other central life activities (American Psychological Association [APA], 2020a; Campbell, 2004). Further described as a contextual phenomenon, the magnitude of its affects prevail in the intel-lectual, cognitive, physical, and social aspects of an individual with disability (Altman, 2001). This limitation often results in requiring additional support to perform in an individual’s natural life (Granlund, 2020; United Nations, 2007). Disability to be understood more clearly can be referred to as a person-environment mismatch due to the inadaptability of the surroundings to accommodate, based on the individual’s disability (Traustadóttir et al., 2015). The global rep-resentation of disability according to the International Classification of Functioning, Disability and Health, is a rather profound explanation to the disability construct defined as a decrement in health which can be experienced by any human being resulting in some degree or form of disability. This description takes disability from a binary to the context of much wider coexist-ing contextual factors (World Health Organization [WHO], 2001) Perhaps, understandcoexist-ing dis-ability through children’s and youth’s experiences is a more practical approach for seekers. However, the label of disability is not a pre-requisite for major obstacles and pressured situa-tions but in fact a phenomenon which is experienced differently throughout the ages and its relation to the environment whether or not adapted to human diversity (Gustavsson et al., 2005; Traustadóttir et al., 2015). In this thesis, disability is defined as a limitation in intellectual func-tioning and adaptive behaviour, part of day-to-day practical, conceptual and social skills (Amer-ican Association on Intellectual and Developmental Disabilities [AAIDD], 2020)

2.2 Intellectual Disability

According to American Association on Intellectual and Developmental Disabilities (AAIDD) and Diagnostic and Statistical Manual of Mental Disorders (DSM-5), intellectual disability (ID) is referred to as a significant limitation in both intellectual functioning and adaptive behaviour. This definition of ID offers the following explanation of intellectual disability in an individual.

(9)

6 1. Deficits in intellectual functioning refer to deficit in intelligence and general mental capacity such as, problem solving, academic learning, learning through experience and reasoning. This is confirmed through clinical assessment and individualized testing. 2. Deficit in Adaptive behaviour highlight limitations in conceptual skills of

developmen-tal and socio-cultural standards for personal independence and social responsibility which are comprised of self-direction, avoid being victimized, social problem solving and social participation; lastly practical skills of undergoing activities of daily life, such as independent living, personal safety and living across multiple environments. 3. Age of onset is conditioned to occur within the developmental age of up to 18 years

according to United States (AAIDD, 2020; APA, 2020b). The level of cognitive func-tioning and limitation in ID is characterized starting from borderline, mild, moderate, severe to profound.

Individuals with ID display restricted response and skills of assertiveness resulting in limited social adaptation which creates an impact on peer acceptance and social interactions negatively (Rosenberg et al., 2008; Swearer et al., 2012). In the longer run, this disadvantage puts them at a greater risk for varied types of peer victimization such as bullying, social exclusion and re-jection (Farmer et al., 2010; Swearer et al., 2012). Moreover the outcomes to these negative events result in negative behavioural and emotional instances including reduced mental health (Emerson et al., 2010; Turner et al., 2013).

2.3 Peer Victimization

Peer victimization is a major multifaceted form of mistreatment, where the victim is repeatedly exposed to emotional and/or physical aggressive behaviour comprising of mockery, teasing, harassment, rumours or social exclusion by peers (APA, 2020c; Olweus, 1994). In line with the definition of peer victimization, its victims usually appear to be physically weak, said to have fewer friends, and exhibit depression and anxiety (Olweus, 1994). This victimization contin-uum is significantly associated to poor mental health which is internalizing behaviour disorders and serious social situations (Graham et al., 2006; Hawker & Boulton, 2000; Perren et al., 2010). Peer victimization in children consists of age-related changes. The experiences and prevalence of peer victimization may take a transitional course from chidhood to adolescence where puberty brings in many developmental changes. In addition to the biological aspect, there is also a significant social transition characterized by the change in peer group (Graham & Juvonen, 1998). These age-related variations can take forms of overt (direct) and covert

(10)

7 (indirect) victimization. The former refers to physical victimization, whilst latter is like spreading rumors. Physical aggression is a common type of peer victimization in younger children however, indirect victimization is more prevalent in adolescence (Juvonen & Graham, 2001). In recent years, another type of victimization which is called ‘cyberbullying’ has emerged widely as a rapidly changing phenomenon (Tsitsika et al., 2015). This term cyberbullying is a form of bullying which occurs via internet or cellphone and has serious affects on children and adolescents worldwide. School going children and adolescents get involved in internet-based activities such as texting, sending emails and using social media with their peers bridging between home and school (Tokunaga, 2010). Several studies confirm the psychological and social harms of cyber victimization of children and adolescents after the use of electronic devices (Kowalski et al., 2016; Tsitsika et al., 2015).

Multiple studies verify that children and adolescents with disabilities are at higher and con-sistent risk of peer victimization compared to typical children with no diagnosed disability (Analitis et al., 2009; Sentenac et al., 2012; Van Cleave & Davis, 2006). A recent systematic review on prevalence of bullying victimization indicated that youth with intellectual disabilities are more commonly victims of bullying and experience many types of victimization such as verbal, physical, and cyber (Maiano et al., 2016).

In general, the harsh and unwanted experiences of victimization are experienced differently at different stages of development from childhood to adolescence making it a heterogeneous phe-nomenon (Juvonen & Graham, 2001).Therefore, this calls for educators, school psychologists, medical practitioners and researchers to be aware of its increasingly adverse consequences on children’s and adolescents’ well-being (Gini & Pozzoli, 2009). Although, awareness of peer victimization has received much attention over the last few decades, research into bullying and peer victimization at school is a relatively recent field of inquiry (Schott & Søndergaard, 2014). Therefore, the available literature particular to factors associated to bullying victimization in children and adolescents with ID is still scarce.

2.4 Peer Victimization and Social Context

Context is defined as interrelated conditions in which something exists or occurs, bounded within a specific setting (Merriam-Webster, 2020). It is an interplay of experiences between an individual’s physical and social dimensions (Batorowicz et al., 2015; Imms et al., 2016). Con-text is where people experience shared activities with others by developing relationships and

(11)

8 connections. Social context affects children and adolescents within the means of a social envi-ronment (Batorowicz et al., 2015). Due to the nature of bullying as a group phenomenon (Ol-weus, 1994), peers within the school environment tend to be a part of many aspects of victimi-zation, largely because of their influential position to characterize the norms and behaviours in a social context (National Academies of Sciences, Engineering, and Medicine, 2016).

In this review, ‘school’ such as upper elementary, middle and high school, comprising of cate-gories known as special and general school, is considered as a primary environment. The school setting consists of objective and subjective features such as discipline, relationship with peers and teachers, school facilities and expectations. In addition to providing opportunities to intel-lectual and social environment to promote health and well-being (Weare, 2000), children and youth are also exposed to adverse situations such as peer victimization in the school context. These negative events can have serious effects on the development of children and can lead to continuous symptoms and disorders towards adulthood (Wang & Dunn, 2018). Among these adverse events, school bullying and peer victimization are major issues occurring in schools around the globe resulting in serious consequences for children and adolescents in physical, psychological, and social domains (Hong & Espelage, 2012)

2.5 Peer Victimization and Psychological Distress

Past literature has consistenly demonstrated the negative outcomes of peer victimization on children and adolescents (Hawker & Boulton, 2000) and its association with poor mental health (Coie & Dodge, 1998; Smith et al., 1999). Psychological distress has found to be saliently associated to victimization experiences (Cole et al., 2010; Rueger & Jenkins, 2014) and these distressing psychological states such as high level of anxiety, depression, and lower levels of self-esteem (Juvonen & Graham, 2001), are also known as internalizing behaviour disorders, a sub category of mental disorders (WHO, 2004). These disorders are directed to one’s inner self (APA, 2020d).

Chiu et al., (2017) assessed adolescents with intellectual disabilities and found that peer victimization was significantly associated with psychological distress making it a notable risk factor. Turner et al., (2010) found mental health problems as potential predictors of peer victimization.

School context plays an important role in children’s and adolescents’ positive perception of interaction with peers. If this interaction is negative such as peer victimization, then it will affect

(12)

9 the psychological well-being of children and adolescents as an outcome (Arseneault et al., 2010; Chiu et al., 2017). On the other hand as a predictor, children and adolescents with intellectual disabilities who display internalizing behaviour disorders are more likely to face obstruction in defending themselves and as a result attract continued victimization (Reijntjes et al., 2010). Therefore, studying the aspect of psychologcial distress as a predictor and an outcome is essential as association to poor mental health in individuals with intellectual disabilities may be apparent due to their neurophysiological and pathopsychological defects (Spencer et al., 2005).

2.6 Biopsychosocial Model

George L. Engel in 1977, introduced the Biopsychosocial Model, to overcome the necessity to broaden the approach to health and illness. His approach was to extend the biomedical perspec-tive and widen the scope of health with the interplay of biological, psychological, and social factors (Engel, 1977). These systems as represented in the model, affect each other persistently (Sarafino & Smith, 2012) as presented in Figure 1 below.

Figure 1: Biopsychosocial model

Knowing that bullying/peer victimization is a root cause of severe psychological complications and a known social stressor for children and adolescents, this phenomenon obstructs the bio-psycho-social growth of an individual who is victimized in a continuum (Plexousakis et al., 2019). This involvement in a negative life event of being bullied leads to the development of internalizing psychopathology and impaired social relationship in the social context of school

Biological Factors Social Factors Psychologi-cal Factors Peer Victimization

(13)

10 (Swearer & Hymel, 2015). The occurrence of peer victimization primarily in the social domain, the third component of the Biopsychosocial framework is to do with control and disctribution of the resources essential for the biological and psychological life of individuals (Bolton & Gillett, 2019). To focus on the chosen population for this review which are the children and adolescents with intellectual disabilities, through the concept of the biopsychosocial model, it is essential to reflect on the status of disability as a constant health condition, with respect to the deficits such as peer victimization faced by children and adolescents with intellectual disa-bilities within the social and psychological domains. As described earlier, individuals with ID as a conditional characteristic, face difficulty in social information processing, adaptive skills, and acquire deficient levels of intellectual functioning (APA, 2013), factors which put these individuals at increased rates for social and psychological dysfunction (Alesi et al., 2015; Ros-enberg et al., 2008). Therefore it is crucial to further understand and indentify the social and psychologcial factors which predict the risk of peer victimization for ID individuals and serve as a consequence.

3 Study Rationale

A systematic review on prevalence and correlates of bullying perpetration and victimization in youth with intellectual disabilities (Maiano et al., 2016) served as a rationale for the present study. This review was based on 11 quantitative articles comprising of three cohort, six case control, and two cross-sectional studies. Besides prevalence rates and correlates of victimiza-tion, the study further reported on time frame, bullying frequency, and the context of victimi-zation which was school setting. The prevalence rate for victimivictimi-zation was found to be 36.3% in youth with intellectual disabilities (Maiano et al., 2016). Finally, mentioning the limited amount of studies that examined the correlates of victimization, the review highlights the need to study and further clarify the individual and contextual factors associated to victimization to tailor effective interventions in the future (Maiano et al., 2016).

3.1 Aim

With respect to the rationale, this systematic literature review aims to critically identify and review the existing literature on the predictors and outcomes which are associated with peer victimization in children and adolescents with intellectual disabilities (ID) in a school environ-ment using the Biopsychosocial model.

(14)

11

3.2 Research Questions

(i) Which predictors are associated with peer victimization in children and adolescents with intellectual disabilities?

(ii) Which outcomes are associated with peer victimization in children and adolescents with intellectual disabilities?

4 Method

4.1 Systematic Literature Review

A systematic literature review was performed to identify the associated factors to peer victimi-zation in children and adolescents with ID. This method was used to provide a transparent means to gather, synthesize and appraise the collective findings of relevant studies on the topic (Jesson et al., 2011). Furthermore, as part of the methodology the review adhered to a set of inclusion and exclusion criteria for search and collection of studies for the systematic review. The chosen scientific methodology helped to assess the quality of chosen articles with the aim to minimise bias linked to sole studies (Jesson et al., 2011).

4.2 Ethical Considerations

This study focuses on children and adolescents and to comply with the Declaration of Helsinki by the World Medical Association (WMA), ethical principles were taken into account during quality assessment of included studies (N=8). This was done on the basis of being approved by ethical board and/or implemented the method of received informed voluntary consent from par-ticipants (WMA, 2013). With respect to the methodology of this systematic literature review, only significant findings from the chosen studies were taken into account to provide the most valuable results. During the process of gathering data, the study excluded information from the included studies which was found to be irrelevant to the proposed research questions.

4.3 Search Procedure

Several selected databases were searched for this systematic literature review in January- Feb-ruary 2020 using ERIC, CINAHL, ProQuest, PsycINFO and Web of Science. ERIC and ProQuest were used as educational databases based on the pre-set inclusion criteria for study selection for peer victimization to have originated and experienced within the school setting.

(15)

12 ProQuest and Web of Science further integrated articles from the field of social sciences. PsycINFO and CINAHL incorporated articles from the disciplines of medical, health science, and psychology.

Advanced search tool was utilized in all the databases for this systematic literature review by applying limiters ‘peer reviewed journal’, ‘English’ as a language of publication, and ‘January 2000 to January 2020’ as publication years from, between and till these dates. Pre-searches were conducted initially using different keywords and thesaurus words but were not found to be useful in terms of either too many or too less hit counts. It was decided before performing the actual search for the retrieval of articles for this review, to use similar keywords (groups of synonyms) in all the databases in order to obtain the most relevant results.

The process of identification of articles was conducted by using potential combinations of groups of search terms and by the application of Boolean operators and truncations such as (i)

disab* OR intellectual* OR impairment* OR ''learning disab*'' OR ''intellectual disab*'' OR ''developmental* disab*''; (ii) bull* ''peer* relation*” OR victim* OR ''cyber bullying'' OR ''peer harassment'' OR “victimization in school’’ (for complete search string see Appendix A).

Further hand search was conducted through snowballing method to retrieve more articles using the reference lists of the identified articles and other systematic reviews relevant to the topic. This entire search procedure with title of databases, dates of searches, search strings and number of retrieved searches were documented via search protocol.

4.4 Selection Criteria

Predetermined inclusion and exclusion criteria (see Table 1) were applied in accordance with Jesson et al., (2011) based on the PICO approach (Richardson, 1995). Studies evaluating peer victimization and correlates through children’s and/or adolescents’ self-reports, both self and parent-reports, and self and teacher-reports were considered. However, studies including only parent and/or teacher reports were excluded during the selection of studies.

Age range for articles was established at 6 years until 21 years. However, diagnostic age of intellectual disabilities was set to have undergone before the age of 18 to adhere to criteria (AAIDD, 2020).

Studies focusing on predictors and/or outcomes correlates of peer victimization were considered. Studies focused on prevalence of victimization only were excluded.

(16)

13 The accepted setting for inclusion was upper elementary, middle to high school levels and articles with other settings were accepted if peer victimization in school setting was also discussed.

Other systematic reviews (however, reference lists were utilized for potential articles), disser-tations, books, reports and any other types of publications outside the inclusion criteria were not considered for the selection of studies.

Table 1: Inclusion and exclusion criteria for selection of studies

Inclusion Criteria Exclusion Criteria

Publication - Articles from peer reviewed journals - English language only

- Publication years January 2000- January 2020

- Not published in English lan-guage

- Publication date outside the inclusion dates

Population - Participants aged from and between 6 – 21 years

-Formal ID diagnosis with/ without comorbidity (e.g. psychiatric disorders, ADHD, ODD)

-Primary diagnosis is not ID

Focus of the study

-Studies focused on peer victimization of children and adolescents with intellectual disabilities/ other disabilities in general with ID population

Bullying involvement/ perpetra-tion only

-For studies including both per-petration and victimization, bul-lying perpetration data and re-sults will be excluded

Study design Quantitative, qualitative, and mixed method studies

Studies which are not peer-re-viewed

4.5 Screening Process

The total amount of articles retrieved from all five databases were 1,076 collectively. The ad-ditional three studies were retrieved from snowballing through the reference list of potential articles and systematic reviews conducted on the topic and were found to be reasonably relevant to the research questions. However, these studies were yet to go through the full text screening process. After initial quick screening of the abstract and title of the pool of articles retrieved, the next step was the removal of duplicates. The initial study design was decided to be both

(17)

14 quantitative and qualititative however, the relevant studies found through databases were mostly quantitative.

4.6 Title and Abstract Screening

Out of 1,076 articles retrieved from ERIC, CINAHL, ProQuest, Web of Science and PsycINFO, 270 articles were forwarded based on title relevancy. These articles were then imported to Ray-yan (Ouzzani et al., 2016), an online tool used for the screening process for systematic literature reviews. Out of 270 articles, 103 were automatically detected as duplicates. Henceforth, 167 articles were identified as potentially relevant to undergo title and abstract screening. Subse-quently, further 151 studies were excluded based on either no presence of disability in the par-ticipant group, concerning only bullying perpetration but no victimization, or focused on inter-ventions for victimization only.

For validity purposes, a second independent reviewer conducted the inter-rater reliability check on 20% of the studies (N= 167) identified as potentially relevant. This review was done at title-abstract screening level and was based on preliminary selection criteria. Disagreements were met on 24% of 33 articles. The author and the reviewer discussed the discrepancies and reached consensus regarding these articles. Finally, leaving 16 eligible articles for full-text screening.

(18)

15

Figure 2: Flowchart of the results of search strategy

Flowchart of the results of search strategy based on Liberati et al., (2009)

4.7 Full- text Screening

All 16 studies were assessed thoroughly as part of the full- text screening using the inclusion and exclusion criteria. The flowchart in Figure 2 mentioned above, represents the step by step procedure of study retrieval and selection process (Liberati et al., 2009). During this process, the primary goal was to focus on the method and results sections of the studies. Therefore, eight articles were excluded based on the inclusion criteria. Amongst the excluded studies, one article measured prevalence of peer victimization only, six articles had no children or adolescents with

1,076 Articles retrieved

ERIC = 86, CINAHL = 63, ProQuest = 304, Web of Science = 317, PsycINFO =

306

270 Articles for title and abstract screening

103 Duplicates removed 167 Articles identified as

poten-tially relevant

151 Excluded based on titles and abstracts.

Reasons: No disability; only bully-ing perpetration; only physical dis-ability; intervention programs only

3 additional articles identified through hand search and snowballing

16 Full-text articles assessed

for eligibility 8 Full-text articles excluded Reasons: Participants without ID; absence of school based peer vic-timization; focus measure not peer victimization; victimization

preva-lence only; no predictors or out-comes of victimization; mother/teacher reports only 8 Articles included in total

(19)

16 intellectual disabilities in the participants groups, and one article only found association be-tween the types of victimization in results. Therefore, after the full text screening was carried out, eight articles were used for subsequent data extraction.

4.8 Data Extraction

Data extraction of all eight articles was carried out by means of an extraction protocol (see

Appendix B). In this step, article information was collected by retrieving the identification

in-formation of studies, research questions mentioned, how and from where the participants were recruited (consent or obligatory), close evaluation of the population of children and/or adoles-cents, presence of a comparison group, data analysis in discussion, limitations, and implications of the study. The most essential part of this step was the identification of variables associated to peer victimization as either predictors, outcomes, or both to get an overview of the collective findings of the studies.

4.9 Quality Assessment

Quality assessment for this systematic review was performed using the Critical Appraisal Skills Program checklists (CASP, 2017) and Joanna Briggs Institute checklist (JBI, 2017) for quanti-tative studies. Since the included articles are cohort, case control and cross-sectional, the check-lists were merged and modified with questions to produce a fit for all the study designs. The protocol is shown in Appendix C. As stated earlier, this systematic review is based on articles with differing research designs, therefore, after the quality appraisal, the scoring was based on the acquired percentages of the fulfilled criteria. Due to the limited amount of qualified articles, it was decided that no articles will be excluded based on a lower quality assessment score. Out of eight studies (see following Table 3 for quality assessment scores), three studies were rated as good quality (>75% of criteria for quality achieved). Four studies were found to be of me-dium quality (≥ 50% of criteria for quality achieved). These studies had inadequate scores in sampling strategy, confounders, missing information about ethical approval, missing data/ drop-outs not mentioned, and generalisability of results. Only one study was declared low qual-ity (<50% of criteria for qualqual-ity achieved) due to insufficient score in sampling strategy, no mention of ethical approval and consent, adjust for confounders, generalisability of results, and missing study implications.

(20)

17

4.10 Data Analysis

Data analysis of the articles was carried out during and after the extraction protocol. Initial analysis comprised of collection of general information from the articles followed by detailed analysis with respect to the research question. An identification number was assigned to each study provided in Table 3 to replace the use of referencing. This step provided an overview of a variety of factors associated to peer victimization and narrowed down to be further categorized as predictors and outcomes. The articles differed in content based on their hypotheses and aims. However, they shared a common ground in terms of prevalence of peer victimization in children or adolescents with intellectual disabilities with further measurements of predictors, outcomes, and predictor-outcome. Some of the articles used different terminologies in describing similar terms for predictors and outcomes. Common terms sharing similar constructs were allocated in a group category for predictors as well as for outcomes belonging to similar constructs.

5 Results

5.1 Overview of included studies

The study designs of the included articles were cross-sectional (five), cohort (two), and case-control (one). The two cohort studies II and V (refer to Table 3 below for identification numbers of studies), had time frames of measurement across two time points at youth ages 13 and 15 years (II), and during 8-, 9-, and 13 years assessments and a center visit at age 13(V).

All studies gathered data from self-reports, added by proxy-ratings in studies III and VI. Par-ticipants were recruited/gathered data, from a variety of schools, agencies, day care programs (III, IV, V, VII), psychiatry services (VII) and larger longitudinal studies (I, II, VIII).

(21)

Table 3: Summary of findings of studies

INS* QAS* Author (year) Country Age

(years)/ Age range ID Level Sample Size ID Total Sample Size Predictors of Victimization Outcomes of Victimization Predictor-Out-come I 79% (Good) Zeedyk, Rodriguez, Tipton, Baker & Blacher (2014)

USA 13 Mild,

Borderline

39 175 Conflict with friend-ships, Internalizing behavior disorders Emotional impact * II 71% (Medium) Tipton-Fisler, Rodri-guez, Zeedyk & Blacher (2018)

USA 13- & -15 Mild, Borderline

39 175 Internalizing behavior disorders, Conflict with friend-ships Reduced quality of friend-ships * III 43% (Low)

Reiter & Lapidot-Lefler (2007)

Israel 12 – 21 Mild 186 186 * * Interpersonal

relations

IV 50%

(Medium)

Didden et al. (2009) Netherlands 12 – 19 Borderline 114 280 * Low self-esteem, Depressive feel-ings * V 71% (Medium) Christensen, Fraynt, Neece & Baker (2012)

USA 8, 9, & -13

Borderline 46 137 Own social

behaviour

* *

VI 79%

(Good)

Chan, Lo & Ip (2018) Hong Kong 6 – 18 * * 4114 Regular school setting

* *

VII 71% (Medium)

Nambiar, Jangam, Roopesh & Bhaskar (2019)

India 10 – 18 Mild, Borderline

40 40 Low self-esteem,

Reg-ular school setting

* *

VIII 86% (Good)

Blake, Zhou, Kwok & Benz (2016)

USA 13 – 16 * 230 2870 Internalizing behavior

disorders, Poor inter-personal skills

* *

(22)

19

5.2 Collective Findings of Included Studies

In line with the aim of this review to identify predictors and outcomes associated to children’s and adolescents’ exposure to peer victimization, all the articles which are used in this systematic review described peer victimization and its correlates which were identified as of predictors, outcomes, and predictor-outcome. Table 3 provides an overview of the articles chosen for this review.

The results are presented in three sections: predictors of peer victimization, outcomes of peer victimization, and the aspect which serves as both predictor and outcome of peer victimization for children and adolescents with intellectual disabilities. These sections are further divided into social and psychological factors.

Table 4: Results of included studies

INS Factors Measured Statistical Analysis Used and Results I (i) Conflict with friendships

(ii) Internalizing behaviour disorders

(iii) Emotional impact

SR and PR of bullying score showed significant positive re-lationship with peer victimization

SR: r(84) = .29, p < .01, PR: r(77) = .24, p < .01

Hierarchical regression analyses was used to explore rela-tionships of SR of peer victimization and other predictive variables, four step regression model indicated increased significance.

R² = .35, F = 4.27, p < .001, 35% variance, at p < .05 SR and PR of bullying score showed similar high relation-ship

Chi-square analysis of emotional impact were significantly higher

II (i) Conflict with friendships (ii)Internalizing behaviour disorders

(iii)Reduced quality of friendships

Chi-square analysis of PR predicted victimization

Chi-square analysis of PR at Time 1 showed increased lev-els of IBD CBCL rates of borderline(T > 60) or at-risk range (T > 63) with victimization

Chi-square analysis of SR and PR showed higher percent-age of lower friendships for ID as compared to TD. III Interpersonal relations Pearson’s Correlation showed significance.

r = .20, p < .05

IV (i)Low self-esteem

(ii)Depressive feelings

Pearson’s Correlation indicated negative correlation with peer victimization

Via internet: r = -0.35, p < 0.01 Via cell-phone: r = -0.31, p < 0.01

Pearson’s correlation indicated positive correlation with peer victimization

Via internet: r= .37, p < 0.01 Via cell-phone: r= .19, p < .05 V Own social

Behaviour

Paired sample t-test showed victimization related to social problems, t = 2.87, p = .005 and to social withdrawal, t = 2.64, p = .01

(23)

20

These two domains showed high correlation, r = .56, p < .001

VI Regular school Setting

Logistic regression for ID, demographic variable, and type of school showed 71.5% victimization for overall disability OR = 1.33; 95% CI [0.67, 1.44]

VII Low self-esteem

Regular school setting

Spearman’s rank correlation coefficient test showed significant negative relationship with peer victimization, r = -0.536, p ≤ .001

Mann-Whitney U test showed significant difference be-tween participants attending regular schools and special schools, U = 51, p ≤ .001

VIII Internalizing behaviour dis-orders

Poor interpersonal skills

Multinomial logistic regression for elevated IBD predicted victimization

OR = 1.31; 95% CI [1.16, 1.46], p ≤.001 Results indicated likelihood of being bullied OR = 1.26; 95% CI [1.10, 1.42], p ≤ .01

SR= Self-report, PR= Parent-report, CBCL= Child Behaviour Checklist, TD= Typical Development

5.3 Predictors of Peer Victimization in Children and Adolescents with

In-tellectual Disabilities

5.3.1 Social Factors

Poor Interpersonal Skills

Study VIII evaluated interpersonal difficulties through a series of items. Within this measure, interpersonal skills were assessed by evaluating the degree to which participants had trouble making initial contacts and introducing themselves to peers. The study further added that par-ticipants with elevated interpersonal difficulties had much likelihood of being victimized.

Own social behaviour

Study V analysed the social variable and assessed the ID individual’s friendships and peer re-lationships through details on involvement in and opinion about school. This data was gathered in three parts. The results of the study found that victimization was related to social problems and social withdrawal, and these two domains correlated highly. The study further added that own social behaviour of youth may account for victimization.

Conflict with friendships

Two studies examined peer relationship by assessing friendships (I, II). Study I explored rela-tionships through youth report of peer victimization and other predictive variables, one of which was conflict with friends. The conflict with friends among other variables was significant (at p

(24)

21 < .05) in predicting higher bullying composite. Study II, analysed youth’s changes in relation-ship and reported that adolescents with more conflict in their friendrelation-ships had a greater likeli-hood of victimization experiences according to mother report.

Regular School Setting

Study VII stated sample characteristics in terms of type of school children were attending. Ac-cording to the study, 57.5% of the participants were in regular schools and 42.5% were placed in special schools. Upon comparing socio-demographic and peer victimization variables signif-icant difference were found in peer victimization between participants’ regular and special school status.

Study VI found that participants with disabilities attending regular schools were more likely to be victimized (71.5%) which proportionated to a high 1.8 to 2.6 times compared to other groups. These children were consistent in reporting different types of victimization.

5.3.2 Psychological Factors

Internalizing Behaviour Disorders

Study I, II, and VIII evaluated internalizing behaviour problems associated to peer victimiza-tion. Study II used a borderline cut-off (T-score > 60) and clinical cut-off (T-score > 63) and examined relationship between adolescent internalizing behaviour disorders and bullying over time. The results indicated that adolescents with significant internalizing behaviour problems scores had a higher likelihood for victimization experiences (See table 4, study II).

Results of study I indicated significant positive relationship for bullying internalizing scores. Mother reported bullying indicated similar significant correlation. Subsequently, hierarchical linear regression showed significance in predicting youth victimization.

Study VIII examined emotional and behavioural functioning. This was assessed by summing up three items that measured frequency of experienced feeling of loneliness, depression, or disliked by others. A higher score was indicative of elevated levels of internalizing behaviour problems. The results indicated that participants who had elevated internalizing behaviour prob-lems were more likely to be victimized.

(25)

22

Low Self-esteem

Study VII analysed relationship between peer victimization and self-esteem. Negative relation-ship with verbal, physical, and social peer victimization was established.

5.4 Outcomes of Peer Victimization in Children and Adolescents with

In-tellectual Disabilities

5.4.1 Social Factor

Reduced Quality of Friendship

Study II conducted analyses to examine youth peer victimization and profile of quality of friendship at Time 2. This was measured on 0-4 scales for positive reciprocity, and warmth/ closeness such as providing social support to each other, desire to spend time with friends, and mutual liking of one another. The chi-square analyses for levels of reciprocity in friendship indicated lower significance in adolescents with ID at Time 2 compared to TD group. Decline in reports of friendships from ages 13 to 15 were reported. Parents of ID adolescents reported lowest frequency (55.9%) of best friends at Time 2.

5.4.2 Psychological Factors

Low Self-esteem

Study IV measured cyberbullying victimization through a four parts questionnaire based on Scholte et al. (2009). Self-esteem was the second part of the questionnaire which consisted of nine questions. Mean score of self-esteem was derived if six questions out of nine were scored. Being a victim of cyberbullying was found to be negatively correlated with self-esteem via both internet and cell phone. The study further added that the more often an individual with ID was victimized via internet and/or cell phone, the less self-esteem s/he reported.

Depressive Feelings

Study IV measured depressive feelings as part of the questionnaire on 12 symptoms. If eight out of twelve questions were endorsed by the participant, then a mean item score was calculated. Pearson correlation between being a victim of cyberbullying and depressive feelings via inter-net indicated a positive correlation and also via cell phone. This result reflected that the more

(26)

23 often the individual with ID was victimized via internet and/or cell phone, the higher were the self-reported depressive feelings.

5.4.3 Social – Physiological Factor

Emotional impact

Study I reported the emotional impact of bullying defined as sadness, anger, and indifference. Only youth and parents who reported earlier that they had been bullied were further asked to respond. This variable consisted of a 6-point scale, among other points a dichotomous variable for emotional impact of being bullied on youth was analysed. According to this analysis, youth reports of emotional impact of being bullied were significantly higher for ID participants (80%) when compared to TD group.

5.5 Predictor - Outcome of Peer Victimization in Children and Adolescents

with Intellectual Disabilities

5.5.1 Social Factor

Interpersonal Relations

Study III performed analyses for children’s behaviours. Upon checking for possible differences between personality variables and social adjustment, significant correlations were found on all scales. The results indicated that the victim status of bullying and having problems in interper-sonal relations with peers were significantly correlated.

Table 5: Effect sizes of predictors and outcome Factors identified Weak/ Small

Effect

Medium Effect Large Effect

Conflict with friendships I*, I**

Internalizing Behaviour Disorders

I I*, I**

Interpersonal Relations III*

Low Self-esteem (internet)IV*,

(cell-phone) IV*

VII* Depressive Feelings (cell-phone)IV* (internet)IV*

Own Social Behaviour V*

(27)

24

Effect size table is based on the statistics found in the studies which represent it such as ‘r’ values and does not include effect sizes of factors which were missing from their prospective studies.

6 Discussion

6.1 Description of Overall Findings

Research has grown in recent years with regards to the prevalence of peer victimization in chil-dren and adolescents with intellectual disabilities and some of the present studies reflect on the correlates as well. However, scholarly articles which may provide an insight into the systematic evaluation of which correlates of peer victimization stand as predictors and the ones which act as potential outcomes are rare. Based on the proposed research questions, this study success-fully identified the predictors and outcomes of peer victimization and thus, adds to the existing literature by providing knowledge of factors associated to peer victimization as prospective predictors and outcomes.

During the content analysis, it was observed that the studies provided more predictors of peer victimization as compared to outcomes due to the majority of studies holding cross-sectional designs. This issue addresses the fact that fewer studies have adopted the longitudinal research methodology which may help in retrieving more certain outcomes of peer victimization in chil-dren and adolescents with intellectual disabilities. Another reason for this observation may be because victims of bullying possess certain attributes and personality traits which add to these unwanted experiences of being victimized by their peers (Olweus, 1994).

Unlike other studies, Reiter & Lapidot-Lefler (2007) was the only study that did not state

inter-personal relations as either a predictive risk for victimization or its outcome. Therefore, it was

decided that it will be discussed as a factor which can occur as both predictor and outcome. Therefore, based on the resulting predictors, outcomes, and predictor-outcome of the studies, further on, the discussion for this systematic review will be presented using the Biopsychosocial model (Engel, 1977) by categorizing the factors into social and psychological domains.

(28)

25

Figure 3: Presentation of results using the Biopsychosocial Model

*Interpersonal Relations act as both predictor and outcome of peer victimization

Level

Regular School Setting Conflict with friendships Poor Interpersonal Skills Interpersonal Relations* Own Social Behaviour

Internalizing Behaviour Disorders Low Self-esteem Psychological Social

Predictors

Peer Victimization Reduced quality of Friendship Interpersonal Relations* Emotional Impact Low Self-esteem Depressive Feelings Psychological Social

Outcomes

Level

(29)

26

6.2 Reflections on findings and implications

6.2.1 Social and Psychological Domains of Peer Victimization

Regular school setting, attended by the victims is found as a predictor of peer victimization for

children and adolescents with intellectual disabilities (Chan et al., 2018; Nambiar et al., 2019). As said, regular inclusive schools are the best means to fight against the society’s stigma towards discrimination of disabilities (UNESCO, 1994). Whereas, if children and adolescents with intellectual disabilities are faced with peer victimization within the realms of inclusive schools, they may continue to face repeated victimization. When compared to children and adolescents with ID attending special schools, these children may not feel protected and safe (Lindsay, 2007). These findings are consistent with another study which also found that ID individuals face more difficulties in social competencies in regular schools (Chiu et al., 2017). Reflecting on the possibility that school environment serves as an essential platform of social context for association between victimization experiences and disabilities , measures to control these instances must be taken by regular schools by spreading awareness amongst children and adolescents to ensure a decline in peers discriminitating eachother based on disability (Sullivan, 2009; Sullivan & Knuttson, 2000).

Conflict with friendships was recognised as a predictor pointing to the inherent inability in

individuals with ID to resolve conflicts with their friends (Tipton-Fisler et al., 2018; Zeedyk et al., 2014). Due to the deprived social adaptation skills, children and adolescents with ID are often misinterpreted by other individuals resulting in uncalled-for victimization experiences. These findings are consistent with Larkin et al., (2012). Furthermore, Reduced Quality of

friendships is identified as an outcome, warranting serious consequences of peer victimization

in children and adolescents with intellectual disabilities (Tipton-Fisler et al., 2018). Both these factors of peer victimization were identified through participants in early adolescence, the age of puberty with rapid developmental changes and physical growth (Petersen & Taylor, 1980). Adolescence brings in the realization of social maturity however, for children and adolescents with ID, bridging from familial circle to peer support is rather a challenge. Knowing these limitations of conflicts and poor friendship quality in the social domain of these individuals make them an easy target for being victimized and may fetch serious social exclusion giving them lesser opportunities to form reciprocated social interactions and going friendless (Graham & Juvonen, 1998). Friendship offers protection against peer victimization and conflict resolution helps in maintaining these friendships through the course of time (Hodges et al.,

(30)

27 1999). Therefore, intervention programs should be implemented by schools to provide directions to children and adolescents in dealing with conflicts and to sustain peer support in children and adolescents with ID to buffer and end peer victimization.

Own social behaviour comprised of social problems and social withdrawal puts individuals

with ID at increased risk for victimization (Christensen et al., 2012). This finding adds to the fact that due to their characteristics, individuals with ID are less likely to develop age-appropriate skills of socialization. These limitations may preclude friendships and thus curtail opportunities for social support. Further pointing towards social withdrawal, this outcome adds to the understanding that children and adolescents with ID, who are socially withdrawn witness more victimization. However, intervening in these same factors which jeopardize their social situation can help them to cope with any further victimization experiences. Laugeson et al., (2009) found that group social skills training produces change within and beyond group context. By improving their social skills, ID children and youth will learn to manage their social problems and free themselves from social withdrawals by forming relationships with peers.

Poor interpersonal skills and interpersonal relations are associated to peer victimization in

terms of predicting it and resulting as both predictor-outcome respectively (Blake et al., 2016; Reiter & Lapidot-Lefler, 2007). These two factors incorporate the social and personality aspects of the victimization phenomenon whereas, also constitute as depriving characteristics which distinguish ID individuals from their peers. Interpersonal skills as a social predictor of victimization exhibit that children and adolescents with ID who are marked by poor interpersonal skills due to their inability to interact with their peers in proscocial ways are at a higher risk for victimization. Being a victim interpersonally, may result in becoming socially unsuccessful, lacking friends, resulting in elevated feelings of loneliness, and peer rejection (Juvonen & Graham, 2001). To conclude, it is essential to surpass the disability status and embark on the importance of social skills in victimization risk for ID individuals (Farmer et al., 2015). Interpersonal relations on the other hand, are how well an individual maintains relationships with the peers. As identified by Reiter & Lapidot-Lefler (2007), peer victimization correlated with interpersonal relations, making it unclear if whether it is a risk or consequence. If these peer relations in developing a child or adolescent are associated with aversive experiences of peer victimization, serious social and emotional consequences may occur (Ju-vonen & Graham, 2001). Therefore, it is essential for schools to nurture the individuals with intellectual disabilites by formulating interventions to maintain better interpersonal

(31)

28 relationships in order to build up the social world around them with mutual understanding between peers and in undermining vicimization.

Emotional impact emerged as an outcome for peer victimization in ID indivuduals which

highlights that children and adolescents who face such maltreatment by their peers experience anger and dissatisfaction (Zeedyk et al., 2014). Emotions, may refer to both social and psychological domains as they are characterized by thought and behavioural changes. Consistent with other studies peer victimization in children and adolescents manifests negative emotions and has a serious impact (Herts et al., 2012; McLaughlin et al., 2009). This finding implicates that schools should focus on enhancing school climate by implementing intervention programs e.g., Olweus bullying Prevention Program (Olweus & Limber, 2010) to monitor incidents of victimization. School staff can play an effective part in identifying children and adolescents with emotional dysregulation to prevent further peer victimization (Herts et al., 2012).

Internalizing Behaviour Disorders in children and adolescents with intellectual disabilities

predict peer victimization (Blake et al., 2016; Tipton-Fisler et al., 2018; Zeedyk et al., 2014). Cappadocia et al. (2012) and Whitehouse et al., (2009) also found similar results in adolescents with ASD and Asperger’s syndrome who had elevated IBD, were more often victimized. Low

Self-esteem as a category of IBD is another factor which contributes to predicting victimization

(Nambiar et al., 2019). According to Olweus (1994), children and adolescents who are victimized usually show elevated internalizing symptoms. The finding is aligned to this statement as a predictive risk for victimization. Additionally, these findings are based on adolescent participants, as discussed earlier, research says that this developmental period is marked by competencies (De Ruiter et al., 2007). During this period, adolescents encounter more stress when they are faced by limitations in their adaptive behaviour. Therefore, it is possible that these individuals develop more internalizing behaviour disorders during their struggle towards adulthood (Bouras, 1994). However, when these individuals with low self-esteem and increased overall IBDs have to experience school life amongst their counterparts which are much more stable, they become victims of bullying. Hodges et al., (1999) found that low self-regard led to higher victimization. Studies also identified that individuals with low self-esteem rarely seek out help as they are predisposed to expect and accept negativity towards them (Juvonen & Graham, 2001).

(32)

29

Depressive feelings and low self-esteem are identified as the psychologcial outcomes of peer

victimization experiences among children and adolescents with intellectual disabilities (Didden et al., 2009). Another study by Eijnden et al., (2006) found similar results that victims of bullying display more psychological problems, negative self-concept, and depressive feelings. Unfortunaltely, for undividuals with ID these experiences may force them deeper into the poor status of mental health. Continued victimization may make them feel unprotected and unsafe, resulting in a negative perception of unpredictable school environment (Juvonen & Graham, 2001).

It is noteworthy here that some of the individual internalizing behaviour disorders are assoicated more to victimization such as low self-esteem and depressive feelings in case of this review. However, their status as pre-or-post victimization differs. Whereas, low self-esteem stands as both. Moreover, pertaining to the description of these psychological factors as reduced mental health conditions and personal characteristics of children and adolescents with intellectual disabilities, schools are obligated to ensure the safety of these individuals from facing these painful events of getting tormented by their peers. It is recommended that special education teachers should be encouraged to observe these children and adolescents with elevated psychological risks and provide training in classrooms to regulate these disorders (Juvonen & Graham, 2001). School psychologists are also advised to counsel the ID individuals intensively to discontinue and hamper victimization.

6.3 Reflections on Findings Related to Biopsychosocial model

The understanding of the findings of this review through the lens of the biopsychosocial model provides a description to the peer victimization phenomenon in school setting for children and adolescents with intellectual disabilities. The social domain has appeared as a dominant level for victimization experiences both in terms of predictors or outcomes. Children and adolescents who are members of caring social groups which are well-disposed towards one another and follow the social rules and regulations of respecting each other will help to avoid risks to ill health. On the other hand, social groupings where they are victimized may affect their psychological dispositions (Bolton & Gillett, 2019). Based on the findings, poor interpersonal skills, deficits in developing interpersonal relations, inability to resolve conflicts within the friendship groups, and own social behaviour of ID individuals is what makes them vulnerable to victimization. Exposure and experiences of peer victimization hamper their future prospects

(33)

30 of maintaining their friendship affiliations and also affects the quality of their peer relationships. For children and adolescents with intellectual disabilities, the status of disability plays an essential role as it imputes deficit in ability to be an active part of the social domain. According to Bolton and Gillett (2019), environment substantially is social and risks for illnesses; physical or mental within the biological domain begin early in childhood during developmental stages through social factors such as social exclusion. Indicated by the findings of this review and consistent with Plexousakis et al., (2019), peer victimization is a significant social stressor and its association ripples through the psychological domain. As discussed by Guralnick (2006), for individuals with ID, social factors contribute to dramatic impairment of psychological well-being. Identification of the psychological aspect of peer victimization is much relevant for Indivudals with ID as they manifest co-occuring psychological issues with problems varying from psychiatric disorders to a range of internalizing difficulties (Guralnick, 2006). Therefore, mal-experiences of victimization may invite more desolation in the psychological domain. To conclude, negative events pf peer victimization involve a complex range of interplay between the biological, psychological, and social levels which cannot be enunciated without the application of biopsychosocial framework.

6.4 Methodological Issues

Three out of eight studies (Blake et al., 2016; Tipton-Fisler et al., 2018; Zeedyk et al., 2014) mentioned internalizing behaviour disorders as predictors. Didden, et al. (2009) mentioned low

self-esteem and depressive feelings as singular outcomes of peer victimization despite their

categorization as internalizing behaviour disorders. This reflects that if not assessed as an entire group, individual evaluation of IBDs can provide deeper meaning to understand and associate them separately to peer victimization. Zeedyk et al., (2014) also found emotional impact as an outcome of being victimized. It was collapsed into both social and psychological domains due to the expressive nature of emotions which can affect health outcomes (Skinner, 2013). A challenge for this systematic review was the retrieval of studies based on the topic. Despite the availability of studies for peer victimization experiences in general population of children and adolescents with disabilities, studies focused mainly on intellectual disabilities are unfor-tunately limited. To cope with this issue, snowballing through other systematic reviews (Alha-boby et al., 2019; Maiano et al., 2016) helped immensely. During the search procedure, many studies that were found, did not clearly mention the types of disabilities until the participant

Peer Victimization of Children and Adolescents with Intellectual Disabilities : A Systematic Literature Review from 2000-2020