To explore if emotional instability is a useful construct in adults with autism spectrum disorder (ASD) and intellectual disability (ID).

The current diagnostic criteria for ASD and ID will be outlined and related to any relevant literature on emotional instability in those with ASD or ID. Recent cross-sectional studies in a clinic and a prison of adults with ASD and/or ID using standardised screening and diagnostic tools will be described.

Current literature indicates there is little research on emotional instability in adults with ASD and ID. Studies across clinic and forensic settings indicate high levels of comorbidity such as attention-deficit hyperactive disorder (ADHD) and mood disorders in adults with ASD and ID.

At present emotional instability as a construct may not have validity for adults with ASD and ID but may do in the context of other comorbid conditions such as ADHD.

The author has not supplied his declaration of competing interest.