Monash University researchers are developing checklists to help general practitioners and support workers recognise depression in people with an intellectual disability.
Dr Teresa Iacono, research director of the Centre for Developmental Disability Health Victoria, said identifying depression in people who had communication problems was notoriously difficult.
The centre, part of Monash's Department of General Practice, aims to improve the quality of health care available to people with developmental disabilities.
Dr Iacono said people with an intellectual disability were prone to mood disorders because of factors such as higher incidence of illness and brain abnormalities, as well as limited social support and poor social and coping skills.
"Depression in such people has been underestimated as there have long been problems with diagnosing their depression due to communication impairment, atypical presentations and lack of reliable and valid diagnostic criteria," Dr Iacono said.
De-institutionalisation had meant GPs were increasingly seeing patients with intellectual disability - but often did not have the training or knowledge to deal with them, she said.
"Problems in accessing assessment and intervention services result from the lack of appropriate assessment tools, the fact that GPs are rarely knowledgeable about intellectual disabilities, and that access to specialist psychiatrists is limited in Australia," Dr Iacono said.