Abstract
Objective: This study addresses the question of how prevalence and patterns of psychiatric disorder change from childhood to adolescence in young people with intellectual disability (ID).
Method: A representative epidemiological sample of 582 young people with ID aged 4–19 years was surveyed in 1991–1992 and again in 1995–1996. The main measure of psychiatric disturbance was the developmental behaviour checklist (DBC), a 96 item parent/carer completed questionnaire with robust psychometric properties which provided an overall score, 6 subscale or syndrome measures of psychiatric disturbance and determined caseness.
Results: The findings confirmed that about 40% of young people with ID had psychiatric disorders which persisted over 4 years. Clinically significant change in symptoms with either deterioration or improvement occurred in around 14% of the sample.
Conclusion: Psychiatric disorder is 3–4 times more prevalent in young people with ID than in the general population. Less than 10% of these young people receive specialist services for a problem which is numerically as large as schizophrenia.
