Diagnostic Overshadowing

A clinical phenomenon in which the symptoms or behaviours of a person with a disability are incorrectly attributed to their existing disability rather than being recognised as signs of a separate condition. In the context of intellectual and developmental disabilities (I/DD), diagnostic overshadowing frequently causes trauma-related effects such as anxiety, depression, and behavioural changes to be dismissed as features of the person's disability rather than investigated as responses to traumatic experiences. This misattribution can lead to people with disabilities not receiving appropriate mental health treatment, and the resulting disregard for their trauma may itself constitute further traumatisation. Awareness of diagnostic overshadowing is important for accessibility practitioners, healthcare providers, and technology designers working with people with disabilities to ensure that co-occurring conditions are properly identified and addressed.