Practice Parameter for the Assessment and Treatment of Psychiatric Disorders in Children and Adolescents With Intellectual Disability (Intellectual Developmental Disorder)

Intellectual disability (intellectual developmental disorder) (ID/IDD) is both a psychiatric disorder and a risk factor for co-occurring psychiatric disorders in children and adolescents. DSM-5 introduced important changes in the conceptualization and diagnosis of ID/IDD, and current research studies clarify assessment and treatment of co-occurring psychiatric disorders in this population. Optimal assessment and treatment of psychiatric illness in children and adolescents with ID/IDD includes modifications in diagnostic and treatment techniques, appreciation of variations in the clinical presentation of psychiatric disorders, an understanding of the spectrum of etiologies of behavioral disturbance, and knowledge of psychosocial and medical interventions. Intellectual disability (intellectual developmental disorder) (ID/IDD) is both a psychiatric disorder and a risk factor for co-occurring psychiatric disorders in children and adolescents. DSM-5 introduced important changes in the conceptualization and diagnosis of ID/IDD, and current research studies clarify assessment and treatment of co-occurring psychiatric disorders in this population. Optimal assessment and treatment of psychiatric illness in children and adolescents with ID/IDD includes modifications in diagnostic and treatment techniques, appreciation of variations in the clinical presentation of psychiatric disorders, an understanding of the spectrum of etiologies of behavioral disturbance, and knowledge of psychosocial and medical interventions. The purpose of this Practice Parameter is to guide clinicians in the assessment and treatment of co-occurring psychiatric disorders in children and adolescents with intellectual disability (intellectual developmental disorder) (ID/IDD). This parameter updates the previous 1999 AACAP parameter1Szymanski L. King B.H. Practice parameters for the assessment and treatment of children, adolescents, and adults with mental retardation and comorbid mental disorders.J Am Acad Child Adolesc Psychiatry. 1999; 38: 5S-31SAbstract Full Text PDF PubMed Scopus (96) Google Scholar on the management of co-occurring disorders and incorporates new research findings and changes in the field. In particular, important changes in the definition and diagnosis of ID/IDD and in the field of genetics have occurred. In the DSM-5, ID/IDD, unlike earlier classifications of mental retardation, is recognized as a psychiatric disorder. A goal of the DSM-5 revision was to emphasize that the psychiatrist has a role in assessing intellectual deficits and in using the severity table to determine adaptive functioning. DSM-5 shifts the focus away from the IQ number to emphasize adaptive reasoning and functioning and facilitates child and adolescent psychiatrists being actively involved in the diagnosis of ID/IDD, including etiological workup and specifiers of severity, as described in the diagnostic manual. An understanding of these procedures and processes assists clinicians working with this population to be most effective in treatment. This parameter assumes familiarity with child development and the principles of child psychiatric diagnosis and treatment. As people with ID/IDD are a heterogeneous group with a wide range of disabilities and strengths, recommendations should be adapted to an individual’s needs. This parameter is an update of the “Practice Parameters for the Assessment and Treatment of Children, Adolescents and Adults with Mental Retardation and Comorbid Mental Disorders,” which was based upon a review of literature published prior to 1999. The current Practice Parameter is based on a comprehensive search of publications produced since 1999. Articles were retrieved from PubMed, PsychInfo, Cochrane, and CENAHL databases. Searches were inclusive and used both MeSH headings and keywords. PubMed was searched using the MeSH Major Topic intellectual disability. The initial search yielded 69,413 articles. This search was limited to English, humans, “all child (0 to 18 years)” and the years from January 1, 1999, to January 21, 2019. In addition, this retrieval was limited to the following: classical article, clinical trial, comparative study, controlled clinical trial, evaluation studies, guideline, historical article, meta-analysis, multicenter study, practice guideline, randomized controlled trial, review, systematic review, twin study, or validation studies. The limited search resulted in 3,651 retrievals. The PsycInfo thesaurus term “Intellectual Disability” gave an assigned heading of Mental Retardation. A search for “Mental Retardation” or “Intellectual Disability” as keywords resulted in 47,532 articles. This search was then limited to English language, human, Childhood: birth to age 12 years, Adolescence: age 13−17 years, and the years from January 1, 1999, to January 21, 2019. The final retrieval was limited to Peer Reviewed Journal, Journal Article, or Review-Book, resulting in a final yield of 3,512 articles. The Cochrane Database of Systematic Reviews was searched using “mental retardation” or “intellectual disabil*”. The reviews were limited from January 1, 1999, to January 21, 1999, resulting in 316 reviews identified. The CINAHL database was searched with the terms Mental Retardation or intellectual disability. Limits applied included English; Human; January, 1999–January, 2019; All child (0−18 years); peer-reviewed articles; abstract available. Medline records were excluded from this search. The search produced 552 articles. The 8,031 articles found through this process were exported into the EndNote referencing program. A total of 44 articles identified by hand-searching or recommended by experts were added. After removing 483 duplicate references, the resulting yield from the comprehensive search was 7,590 articles. The titles and abstracts of all 7,590 articles were reviewed and 1,067 articles were included for full-text examination (Figure 1). A total of 258 publications were included in the qualitative synthesis based on their relevance to the parameter topic, weight in the hierarchy of evidence, quality of individual studies, and relevance to clinical practice. In this parameter, unless otherwise noted, the term Intellectual Disability (Intellectual Developmental Disorder) (ID/IDD) refers to intellectual disability as an intellectual developmental disorder. This parameter uses the term Global Developmental Delay when clinical severity cannot be reliably assessed in early childhood (under age 5) and the term Unspecified Intellectual Disability (Intellectual Developmental Disorder) for children over age 5 when other impairments make assessment difficult. The term child or children refers to both children and adolescents, and parents refers to the child’s primary caregivers, regardless of whether they are the biological or adoptive parents or legal guardians. Changes in the terminology used for individuals with ID/IDD reflect society’s perception of this population. In the 19th century, the now-unacceptable terms “cretin,” “idiot,” and “imbecile” were used, reflecting an era when these individuals were commonly housed in overcrowded asylums and institutions.2King B.H. Toth K.E. Hodapp R.M. Dykens E.M. Intellectual disability.in: Sadoc B.I.J. Sadock V.A. Ruiz P. Comprehensive Textbook of Psychiatry. 9th ed. Lippincott Williams & Wilkins, Philadelphia, PA2009: 3444-3747Google Scholar Many of these institutions were built during the height of the eugenics movement with the goal of preventing people with even mild ID/IDD from reproducing. Sterilization, often without consent or even the person’s foreknowledge, was practiced during the eugenic era. In 1961, the American Association on Mental Retardation (AAMR) introduced the term “mental retardation” to replace earlier terms that had become pejorative. By the 1970s, the de-institutionalization movement began to provide community care. Social Security Income for this population became available, and it was assumed that community-based care could absorb and adequately provide for their needs. A movement to assess and to treat co-occurring psychiatric disorders in individuals with ID/IDD was underway, but, unfortunately, few psychiatrists had training. By the 1980s, instruments for assessment of co-occurring psychiatric disorders were developed. Since then, evidence-based principles for assessment and treatment have been developed, and specific training incorporated into psychiatric curricula.2King B.H. Toth K.E. Hodapp R.M. Dykens E.M. Intellectual disability.in: Sadoc B.I.J. Sadock V.A. Ruiz P. Comprehensive Textbook of Psychiatry. 9th ed. Lippincott Williams & Wilkins, Philadelphia, PA2009: 3444-3747Google Scholar The most recent conceptual paradigm shift began in 1992, when the American Association on Intellectual and Developmental Disabilities’ (AAIDD) new definition placed greater emphasis on the disability construct by changing the earlier term “mental retardation” to “intellectual disability.” The premise is that a disability occurs when the demands of the environment exceed an individual’s ability. Thus, environmental modifications or social supports can ameliorate the extent to which a condition limits an individual’s functioning.3Harris J.C. Intellectual Disability: Understanding its Development, Causes, Classification, Evaluation, and Treatment. Oxford University Press, New York, NY2006Google Scholar This paradigm shift has helped frame intellectual disability not as a static condition, but one that can be enhanced by the provision of supports.4Schalock R.L. Borthwick-Duffy S.A. Bradley V.J. et al.Intellectual Disability: Definition, Classification, and Systems of Supports. American Association on Intellectual and Developmental Disabilities, Washington, DC2010Google Scholar In 2013, the American Psychiatric Association’s (APA) fifth edition of the DSM-55American Psychiatric AssociationDiagnostic and Statistical Manual of Mental Disorders. 5th ed. (DSM-5). American Psychiatric Association, Arlington, VA2013Crossref Google Scholar also revised the diagnostic term from “mental retardation” to “intellectual disability (intellectual developmental disorder).” However, unlike AAIDD’s focus on the disability construct, the DSM-5 focus is on the developmental disorder construct in keeping with the World Health Organization’s (WHO) International Classification of Diseases (ICD-11). In ICD-11, these are recognized as disorders of neurodevelopment and “described as a metasyndrome occurring in the developmental period analogous to dementia or neurocognitive disorder in later life.”5American Psychiatric AssociationDiagnostic and Statistical Manual of Mental Disorders. 5th ed. (DSM-5). American Psychiatric Association, Arlington, VA2013Crossref Google Scholar The APA revised the criteria for ID/IDD to focus on four levels of severity of impairment based on adaptive functioning across conceptual, social, and practical domains. Intelligence Quotient (IQ) scores are not used in DSM-5 to define levels of severity.5American Psychiatric AssociationDiagnostic and Statistical Manual of Mental Disorders. 5th ed. (DSM-5). American Psychiatric Association, Arlington, VA2013Crossref Google Scholar The field and federal law have adopted “person first” language (“a person with intellectual disability”), and clinicians should incorporate this form of reference in their communications with and about individuals with ID/IDD. There are many causes of ID/IDD that reflect complex interactions of genetic predisposition, environmental insults, and developmental vulnerability. An etiology can be identified for the majority of individuals with severe ID and for a substantial subset of individuals with mild ID.3Harris J.C. Intellectual Disability: Understanding its Development, Causes, Classification, Evaluation, and Treatment. Oxford University Press, New York, NY2006Google Scholar The classification of causes of ID has generally focused on both the type of risk factor and its timing, including prenatal, perinatal, and postnatal events. Single-gene disorders or syndromes result from disruptive variants in an individual gene, which can be found only in the child (de novo variants) or can be inherited from the parents in a dominant, recessive, or X-linked fashion. The most common inherited cause of ID/IDD is Fragile X syndrome, resulting from a repeat variant in the FMR1 gene on the X chromosome. Some single-gene disorders result in brain malformations, such as absence of cortical folds (lissencephaly) or abnormal layering of the cortex. Other single-gene disorders include neurocutaneous syndromes such as tuberous sclerosis or neurofibromatosis. Inborn errors of metabolism result from disruption of individual genes that encode enzymes that metabolize carbohydrates, amino acids, or nucleic acids, as well as mitochondrial defects. Chromosomal or copy number variant disorders result from either an extra copy or a missing copy of an entire chromosome or a chromosomal segment. The major chromosomal disorders are 3 autosomal trisomies (13, 18, and 21), with trisomy 21 (Down syndrome) being the most common genetic cause of ID/IDD. Beyond single-gene, chromosomal, and copy number variant disorders that contribute a large amount of risk, genetic variants in many genes likely contribute a smaller amount of ID/IDD risk, particularly in children with mild ID/IDD, where multiple genetic and environmental risk factors may converge to lead to ID/IDD. ID/IDD also has prenatal environmental risk factors, including malnutrition, vitamin or mineral deficiency, placental insufficiency, in utero exposures including alcohol, drugs, toxins, or teratogens, and maternal illness such as hypothyroidism. Fetal alcohol spectrum disorders are the leading cause of preventable developmental disabilities in the world.6Hoyme H.E. Kalberg W.O. Elliott A.J. et al.Updated clinical guidelines for diagnosing fetal alcohol spectrum disorders.Pediatrics. 2016; 138: 2015-4256Crossref Scopus (371) Google Scholar Pre- and perinatal infections can also affect the developing fetus directly, including toxoplasmosis, syphilis, varicella-zoster, parvovirus B19, rubella, cytomegalovirus, and herpes. Although some of these infections cause mild maternal illnesses, they can have serious fetal consequences, and treatment of the mother may have limited impact on fetal outcomes. The timing of an environmental insult during fetal development is crucial in determining the type and severity of impact on the fetus. During delivery, asphyxia is the most important risk factor for brain damage that may lead to ID/IDD. Prematurity and low birth weight, risk factors for asphyxia, as well as intracranial hemorrhage and hypoglycemia increase risk for brain damage. Placental insufficiency and intrauterine events during labor and delivery (ie, eclampsia, premature rupture of membranes) may lead to neonatal hypoxic−ischemic encephalopathy and ID/IDD. Because ID/IDD may have onset throughout the developmental period, postnatal risk factors, potentially occurring as late as adolescence, can also lead to a diagnosis. Brain trauma, near-drowning, and other accidents that result in loss of consciousness can cause brain injury. Infections such as meningitis and encephalitis may also lead to permanent brain damage. Poisoning from lead and other substances contributes to ID/IDD risk, and severe environmental deprivation, child abuse, and neglect can also result in ID/IDD. Medical conditions such as brain tumors or intractable epilepsy also increase risk of ID/IDD, as can some surgical, radiation, or chemotherapy treatments. A child or adolescent without ID who experiences a change in cognitive functioning due to tumor, hypoxemia, or other central nervous system insult may be considered to have either traumatic brain injury (TBI) or ID, depending on the criteria of the state in which that individual resides. This determination may generate confusion, as those with acquired brain injury typically have a developmental pathway and set of needs that are different from those of individuals who have had lifelong ID/IDD. A recent meta-analysis estimated the overall prevalence of ID/IDD to be 10.37 per 1,000 population,7Maulik P.K. Mascarenhas M.N. Mathers C.D. Dua T. Saxena S. Prevalence of intellectual disability: a meta-analysis of population-based studies.Res Dev Disabil. 2011; 32: 419-436Crossref PubMed Scopus (912) Google Scholar about 1%, similar to individual studies conducted in developed countries. The prevalence of ID/IDD in children was 18.3 per 1,000 population and was higher in males than in females. The primary risk factor was equally distributed across prenatal (including genetic), perinatal, and postnatal causes, although it was unknown in almost half of the cases. The prevalence in low-income (16.41/1,000 persons) and middle-income (15.94/1000) countries was much greater than in high-income countries (9.21/1,000). This difference has been hypothesized to be due to decreased access to, or the quality of, maternal and child health care facilities and perinatal screening methods.8Dave U. Shetty N. Mehta L. A community genetics approach to population screening in India for mental retardation—a model for developing countries.Ann Hum Biol. 2005; 32: 195-203Crossref PubMed Scopus (10) Google Scholar Differences in the methodologies of prevalence studies may also contribute to the varying results, as studies in higher-income countries were more likely to use standard assessments and diagnostic systems.7Maulik P.K. Mascarenhas M.N. Mathers C.D. Dua T. Saxena S. Prevalence of intellectual disability: a meta-analysis of population-based studies.Res Dev Disabil. 2011; 32: 419-436Crossref PubMed Scopus (912) Google Scholar ID/IDD involves impairments in general mental abilities that affect adaptive reasoning in three domains: conceptual, social, and practical. Abilities in these domains determine individuals’ effectiveness in functioning with everyday tasks at the level expected for their age and sociocultural background. Conceptual reasoning includes reading, writing, language, mathematics, knowledge, memory, problem solving, and judgment in novel situations. Social reasoning includes awareness of others’ thoughts, feelings, and experiences; social judgment and understanding; interpersonal communication skills; and social problem solving. Practical reasoning includes self-management across life settings and includes personal care, responsibilities, transportation, finances, school and work organization, and occupational skills.4Schalock R.L. Borthwick-Duffy S.A. Bradley V.J. et al.Intellectual Disability: Definition, Classification, and Systems of Supports. American Association on Intellectual and Developmental Disabilities, Washington, DC2010Google Scholar,5American Psychiatric AssociationDiagnostic and Statistical Manual of Mental Disorders. 5th ed. (DSM-5). American Psychiatric Association, Arlington, VA2013Crossref Google Scholar Limitations in intellectual ability may impair learning from instruction and experience, practical understanding, reasoning, judgment in novel situations, and assessment of risk. Limitations in these areas, however, often coexist with strengths. For example, individuals with ID/IDD may have difficulty with conceptual reasoning (such as judgment in novel situations), but may have strengths in practical and social reasoning (such as recognition of others’ thoughts and feelings and ability to attend to their own personal care). An appreciation of an individual’s strengths and weaknesses facilitates individualization of supports. Children generally come to clinical attention based upon observed delays in achieving developmental milestones, and as cognitive, social, and practical demands increase over time and reveal disparities between environmental expectations and the capacity of the individual. The mismatch in ability and expectations may be associated with frustration, adversely affect self-esteem, and lead to behavioral disturbances, which often lead to the assessment that reveals the presence of ID/IDD. Onset of intellectual disability is defined in DSM-5 as occurring during the developmental period.5American Psychiatric AssociationDiagnostic and Statistical Manual of Mental Disorders. 5th ed. (DSM-5). American Psychiatric Association, Arlington, VA2013Crossref Google Scholar The age and presentation at onset depends on the etiology and the severity of ID/IDD.5American Psychiatric AssociationDiagnostic and Statistical Manual of Mental Disorders. 5th ed. (DSM-5). American Psychiatric Association, Arlington, VA2013Crossref Google Scholar In the first 2 years of life, delayed motor, language, and social milestones may be identified in individuals with severe ID/IDD, whereas mild ID/IDD may not be identified until school age, when difficulties in academic learning become apparent.5American Psychiatric AssociationDiagnostic and Statistical Manual of Mental Disorders. 5th ed. (DSM-5). American Psychiatric Association, Arlington, VA2013Crossref Google Scholar Although ID/IDD is generally lifelong, it is not a static disability. The level of cognitive impairments and adaptive skills may change over time, especially as the demands of the environment change (eg, as a youth leaves school and enters the workplace). Early and ongoing interventions may improve adaptive functioning throughout childhood and adulthood. In some cases, these result in significant improvement in intellectual functioning, such that the diagnosis of ID/IDD is no longer appropriate.5American Psychiatric AssociationDiagnostic and Statistical Manual of Mental Disorders. 5th ed. (DSM-5). American Psychiatric Association, Arlington, VA2013Crossref Google Scholar In addition, impairments can be reduced by provision of personalized services and supports to maximize adaptive ability.3Harris J.C. Intellectual Disability: Understanding its Development, Causes, Classification, Evaluation, and Treatment. Oxford University Press, New York, NY2006Google Scholar,4Schalock R.L. Borthwick-Duffy S.A. Bradley V.J. et al.Intellectual Disability: Definition, Classification, and Systems of Supports. American Association on Intellectual and Developmental Disabilities, Washington, DC2010Google Scholar Cognitive and adaptive impairments may also improve with treatment of co-occurring medical conditions (eg, epilepsy, hearing loss, or visual impairments) or worsen with progression of genetic disorders (eg, Rett syndrome).5American Psychiatric AssociationDiagnostic and Statistical Manual of Mental Disorders. 5th ed. (DSM-5). American Psychiatric Association, Arlington, VA2013Crossref Google Scholar The diagnosis of an intellectual disability is made when the DSM-5 criteria are met and other disorders have been adequately ruled out as the etiology. ID/IDD must be differentiated from specific learning disorders, communication disorders, major and mild neurocognitive disorders, autism spectrum disorder, and disorders that could affect performance for intelligence or adaptive skills when tested, such as affective disorders or psychosis. ID/IDD should not be assumed to be due to a genetic or medical condition. However, if a genetic or medical condition linked to ID/IDD is present, it should be noted in the diagnosis of ID/IDD.5American Psychiatric AssociationDiagnostic and Statistical Manual of Mental Disorders. 5th ed. (DSM-5). American Psychiatric Association, Arlington, VA2013Crossref Google Scholar Psychiatric disorders occur at least three times more often in children and adolescents with ID/IDD than in children with typical development.9Emerson E. Einfeld S. Emotional and behavioural difficulties in young children with and without developmental delay: a bi-national perspective.J Child Psychol Psychiatry. 2010; 51: 583-593Crossref PubMed Scopus (113) Google Scholar,10Dekker M.C. Koot H.M. DSM-IV disorders in children with borderline to moderate intellectual disability. I: prevalence and impact.J Am Acad Child Adolesc Psychiatry. 2003; 42: 915-922Abstract Full Text Full Text PDF PubMed Scopus (269) Google Scholar Particularly high rates have been reported for oppositional defiant disorder (ODD), attention-deficit/hyperactivity disorder (ADHD), and anxiety disorders.9Emerson E. Einfeld S. Emotional and behavioural difficulties in young children with and without developmental delay: a bi-national perspective.J Child Psychol Psychiatry. 2010; 51: 583-593Crossref PubMed Scopus (113) Google Scholar,10Dekker M.C. Koot H.M. DSM-IV disorders in children with borderline to moderate intellectual disability. I: prevalence and impact.J Am Acad Child Adolesc Psychiatry. 2003; 42: 915-922Abstract Full Text Full Text PDF PubMed Scopus (269) Google Scholar Autism spectrum disorder (ASD) also commonly co-occurs with ID,9Emerson E. Einfeld S. Emotional and behavioural difficulties in young children with and without developmental delay: a bi-national perspective.J Child Psychol Psychiatry. 2010; 51: 583-593Crossref PubMed Scopus (113) Google Scholar,10Dekker M.C. Koot H.M. DSM-IV disorders in children with borderline to moderate intellectual disability. I: prevalence and impact.J Am Acad Child Adolesc Psychiatry. 2003; 42: 915-922Abstract Full Text Full Text PDF PubMed Scopus (269) Google Scholar as does fetal alcohol spectrum disorder (FASD), also known as neurodevelopmental disorder associated with prenatal alcohol exposure (ND-PAE).5American Psychiatric AssociationDiagnostic and Statistical Manual of Mental Disorders. 5th ed. (DSM-5). American Psychiatric Association, Arlington, VA2013Crossref Google Scholar In addition, serious behavioral problems have been reported to occur 2.5 to 4 times more frequently in children with ID/IDD compared to children with typical development.11Emerson E. Hatton C. Mental health of children and adolescents with intellectual disabilities in Britain.Br J Psychiatry. 2007; 191: 493-499Crossref PubMed Scopus (365) Google Scholar, 12Dekker M.C. Koot H.M. Ende J.V.D. Verhulst F.C. Emotional and behavioral problems in children and adolescents with and without intellectual disability.J Child Psychol Psychiatry. 2002; 43: 1087-1098Crossref PubMed Scopus (351) Google Scholar, 13De Ruiter K.P. Dekker M.C. Douma J.C.H. Verhulst F.C. Koot H.M. Development of parent- and teacher-reported emotional and behavioural problems in young people with intellectual disabilities: does level of intellectual disability matter?.J Appl Res Intellect Disabil. 2008; 21: 70-80Google Scholar Although there is a dearth of rigorous studies examining how the presentation of psychiatric disorders may be altered in the context of atypical intellectual development, the course of some co-occurring psychiatric disorders is becoming better known, particularly for ADHD and anxiety.14Neece C.L. Baker B.L. Blacher J. Crnic K.A. Attention-deficit/hyperactivity disorder among children with and without intellectual disability: an examination across time.J Intellect Disabil Res. 2011; 55: 623-635Crossref PubMed Scopus (42) Google Scholar, 15Baker B.L. Neece C.L. Fenning R.M. Crnic K.A. Blacher J. Mental disorders in five-year-old children with or without developmental delay: focus on ADHD.J Clin Child Adolesc Psychol. 2010; 39: 492-505Crossref PubMed Scopus (104) Google Scholar, 16Reardon T.C. Gray K.M. Melvin G.A. Anxiety disorders in children and adolescents with intellectual disability: prevalence and assessment.Res Dev Disabilities. 2015; 36: 175-190Crossref Scopus (28) Google Scholar Individuals with ID/IDD experience a developmental course of ADHD similarly to that of typically developing children, with more prominent hyperactivity symptoms earlier in development. Inattentive symptoms, which tend to decrease in the teen years in children with typical development, do not typically decrease in children with ID/IDD.17Neece C.L. Baker B.L. Crnic K. Blacher J. Examining the validity of ADHD as a diagnosis for adolescents with intellectual disabilities: clinical presentation.J Abnorm Child Psychol. 2013; 41: 597-612Crossref PubMed Scopus (24) Google Scholar Co-occurring anxiety disorders in youths with ID/IDD vary in prevalence by age, as in children with typical development; however the reduction in the rate of separation anxiety disorder in children with ID/IDD occurs over a longer period of time than in children with typical development.16Reardon T.C. Gray K.M. Melvin G.A. Anxiety disorders in children and adolescents with intellectual disability: prevalence and assessment.Res Dev Disabilities. 2015; 36: 175-190Crossref Scopus (28) Google Scholar Risk factors for co-occurring psychiatric disorders include the severity of cognitive, adaptive, and language impairments, socialization deficits, low family socioeconomic status, trauma, and having a single biological parent as a caregiver.18Koskentausta T. Iivanainen M. Almqvist F. Psychiatric disorders in children with intellectual disability.Nord J Psychiatry. 2002; 56: 26-131Crossref Scopus (27) Google Scholar Certain genetic syndromes are associated with increased rates of psychiatric and behavioral disorders. Table 119Siegel M.S. Smith W.E. Psychiatric features in children with genetic syndromes: toward functional phenotypes.Pediatr Clin N Am. 2011; 58: 833-864Abstract Full Text Full Text PDF PubMed Scopus (14) Google Scholar lists behavioral phenotypes and psychiatric features in certain genetic syndromes associated with ID/IDD.Table 1Behavioral Phenotypes and Psychiatric Features in Specific Genetic SyndromesaAdapted from Siegel et al.19Diagnosis (Mutation)Diagnostic TestingCognitive FeaturesPsychiatric FeaturesDown syndrome(Trisomy 21)Diagnostic Testing: KaryotypeMild−moderate to severe intellectual disabilityStrengths: grammarWeaknesses: