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Dual diagnosis refers to individuals with intellectual disability and a mental illness. Approximately 3 % of the population are diagnosed with an intellectual disability. Prevalence rates of diagnosed mental illness vary, however the agreed prevalence is 39 % of the population with intellectual disability also have a mental illness. ◦ This equates to 250,000 people in Australia (based on population estimates) Focus on schizophrenia in this presentation. Schizophrenia is characterised by ◦ Distortions of thinking and perception ◦ Blunted or inappropriate affect ASSID Conference 2008 Recently accepted that individuals with intellectual disability can experience mental illness. ◦ It was thought that individuals with intellectual disability were protected from psychological stressors that contribute to the onset of mental illness due to reduced cognitive abilities . Now it is recognised that individuals with intellectual disability can be more vulnerable to mental illness, perhaps due to poorly developed coping strategies. ASSID Conference 2008 In the general population, when a person becomes unwell, they are generally able to answer questions in a diagnostic interview. In people with intellectual disability, communication abilities are less functional, and answering the same q estions sed in a general pop lation diagnosticu u u interview can be unreliable. Psychiatrists look for behavioural correlates of emotional disturbances to aid diagnosis Psychiatrists rely on a combination of self-report, carer-report, and behavioural observations to diagnose the presence of a mental illness