Bias in Assessment of Co-Occurring Mental Disorder in Individuals with Intellectual Disabilities: Theoretical Perspectives and Implications for Clinical Practice

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.