Bias in assessment of co-occurring mental disorder in individuals with intellectual disabilities: Theoretical perspectives and implications for clinical practice

Abstract

Influence from bias is unavoidable in clinical decision-making, and mental health assessment seems particularly vulnerable. Individuals with intellectual disabilities have increased risk of developing co-occurring mental disorder. Due to the inherent difficulties associated with intellectual disabilities, assessment of mental health in this population often relies on a different set of strategies, and it is unclear how these may affect risk of bias. In this theoretical paper, we apply recent conceptualisations of bias in clinical decision-making to the specific challenges and strategies in mental health assessment in intellectual disabilities. We suggest that clinical decision-making in these assessments is particularly vulnerable to bias, including sources of bias present in mental health assessment in the general population, as well as potential sources of bias which may be specific to assessments in this population. It follows that to manage potential bias, triangulating information from multi-informant, multi-method, interdisciplinary assessment strategies is likely to be necessary.

Schizophrenia in autistic people with intellectual disabilities: Symptom manifestations and identification

“…Interpreted in light of the hierarchical approach, reported anxiety and depressive symptoms may have been understood as part of these individuals' schizophrenia, instead of as symptoms of a co‐occurring disorder (see Waszczuk et al, 2020). Other possible explanations include diagnostic bias (Kildahl et al, 2023), that anxiety or depressive symptoms were overlooked due to atypical symptom manifestations (Bakken et al, 2016; Keller & Bari, 2019), and demands of the clinical environment. Either way, elevated scores on the PAC scales for anxiety and depressive symptoms in participants with schizophrenia indicate that these symptoms were common among these participants.…”

“…These include difficulties verbally conveying subjective experiences of symptoms, lack of appropriate assessment tools and adapted diagnostic criteria, atypical symptom expressions, and diagnostic overshadowing (Reiss et al, 1982; see also Helverschou et al, 2011). These challenges are likely to be increased in autistic people with intellectual disabilities, in part due to these individuals' often limited verbal language skills (Bakken et al, 2016; Deb et al, 2022; Fletcher et al, 2017; Kildahl et al, 2023; Underwood et al, 2015). There are checklists and diagnostic tools available for the assessment of mental disorder in people with intellectual disabilities (Fletcher et al, 2016; Helverschou et al, 2020).…”

A psychological approach to diagnosis.

“…Depending on the presenting problems, these may include a summary of symptoms, functional assessments, clinical interviews, and case history including personal, educational/ vocational, family, medical, and social history, as well as results from psychological and other tests. It is critical for the clinician to be aware that the diagnostic process can be prone to errors, particularly those due to the clinician's biases or customary patterns of practice (Kildahl et al, 2023;Liu et al, 2022). Using multiple assessment methods and multiple sources of information reduces the risk of the clinician leaping prematurely from an initial clinical impression to a diagnosis without adequately assessing pertinent and potentially contradictory information.…”

Post-traumatic stress disorder and experiences involving violence or sexual abuse in a clinical sample of autistic adults with intellectual disabilities: Prevalence and clinical correlates

“…Moreover, while anxiety and depressive disorders are diagnosed from symptom manifestations alone, diagnosing PTSD requires substantiating an association between a previous traumatic experience and the development of symptoms, in addition to recognising the appropriate symptoms (American Psychiatric Association, 2013). Thus, diagnosing PTSD in autistic people with intellectual disabilities will require practitioners to make more extensive inferences about these individuals' subjective experience than diagnosing anxiety or depression (Kildahl et al, 2021(Kildahl et al, , 2023.…”

“…Mental health assessment in autistic people with intellectual disabilities often relies on information from proxy informants, due to these individuals’ often limited verbal communication abilities (Bakken et al, 2016; Deb et al, 2022; Kildahl et al, 2023). Thus, assessment of PTSD requires the traumatic experience to be known to, and understood as traumatic by, informants.…”