A diagnosis of intellectual disabilities can paradoxically act as a barrier to accessing services, known as diagnostic overshadowing, where symptoms of a mental health condition are misinterpreted as characteristics of intellectual disabilities. For example, a person with intellectual disabilities presenting with low mood or withdrawal may be misinterpreted as ‘just part of their intellectual disabilities’ rather than being recognized as experiencing depression or trauma. 

Diagnostic Overshadowing

In the UK, over 1.3 million people live with an intellectual disability; many also experience co-occurring mental health conditions, such as anxiety, depression, or psychosis. People with intellectual disabilities often have a co-occurring neurodevelopmental difference rates are 33.4% for autism, 9.0% for ADHD, and 10.6% for Down syndrome.

University of North Texas

This article is informed by a social worker and their lived experience at the intersection of intellectual disability, neurodivergence, and mainstream mental health services.

Intersectionality from the Perspective of a Social Worker

Williams, N., Tuomainen, H., & Taylor, J. (2026). Lost in the system: rethinking mainstream mental health services for people with intellectual disabilities. Disability & Society, 1–6. https://doi.org/10.1080/09687599.2026.2634347 



Lost in the system: rethinking mainstream mental health services for people with intellectual disabilities

The author is "autistic and ADHD-identified researcher, a parent in a multi-neurodivergent household, and a Black woman who has experience of systemic inequities within education and healthcare. " The central idea of this article revolves around the issues such as diagnostic overshadowing, service exclusion, and unequal access to care. 

Naomi Williams

Data on Co-occurring Conditions

In a co-designed project Making Mental Health Services Better for Neurodivergent Children and Families, 38 young people, parents and carers with lived experience shared their journeys of seeking help and engaging with mental health services.

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