Dual Diagnosis

Dual diagnosis is a term used to describe mental health issues experienced by people with a developmental disability. Sometimes, dual diagnosis identifies issues that are usually referred to as concurrent disorders, that is, psychiatric illness and addiction.

Signs and Symptoms

In dual diagnosis, the problems include psychiatric disorders such as schizophrenia, mood and anxiety disorders as well as behavioural challenges including aggression. Developmental disabilities include intellectual, autistic spectrum disorders, and genetic syndromes that affect development. The vast majority of developmental disorders include intellectual disability, and most dual diagnosis programs focus on individuals with at least a mild level of disability. A common misconception is that psychiatric illness is not found in people with an intellectual disability; in fact, the incidence of the major psychiatric illnesses is greater than the intellectually disabled than in the typical population.


Services include consultation with individuals, families, primary care physicians and secondary level psychiatrists and hospitals, on both an outpatient and inpatient basis.

Related Links

Canadian Mental Health Association: www.cmha.ca

National Association on Dually Diagnosed: www.thenadd.org

National Association for the Dually Diagnosed  www.thenadd.org