Research projects

Diagnosis and treatment of depression in adults with intellectual disability through general practitioner and psychiatric collaboration

Principal Researchers

Principal Researchers:  Dr Jennifer Torr (1) and Dr Teresa Iacono (1)

Investigators:  Dr Jean Graham (1) and Ms Jennifer Galea (1)

Associate Researchers:  Prof. Bruce Tonge (2) and Assoc. Prof Stewart Einfeld (3)


1 Centre for Developmental Disability Health Victoria, Monash University

2 Centre for Developmental Psychiatry & Psychology, Monash University

3 School of Psychiatry, University of NSW



Award Type

Beyond Blue Victorian Centre of Excellence

Project completion year


Project brief

Psychiatric disorders are 3-5 times more common in people with intellectual disability (ID), but are often overlooked because of communication difficulties and problems with diagnostic accuracy.  Challenging behaviours are common presenting features of psychiatric disorders.  However, If people with an ID demonstrate a challenging behaviour, this behaviour is often attributed to the ID rather than to an underlying psychiatric disorder.  This can negatively impact upon the choice and outcome of behavioural treatments for people with ID, if treatment is required.

Standard diagnostic criteria for psychiatric disorders, have not yet been validated for use with people with ID. People with ID may not be able to give an adequate history or report of their subjective experiences, such as mood, thoughts and perception, because of communication difficulties due to impairments in language development, expression, comprehension and conceptual thought. 

This project aimed to develop, trial and assess screening tools in the form of a checklist for use by direct support workers (DSW) and general practitioners (GPs) to assist in identifying possible depression in adults with ID. 

Participants were recruited from the Department of Human Services and non-government accommodation services. Support workers completed checklists for 49 participants with ID; GPs completed checklists for 27 of these participants.  All participants with ID received a one-off psychiatric consultation by a senior psychiatry registrar.  Their DSWs and GPs were provided with a written psychiatric report with management recommendations.

Consensus meetings with the clinicians and consultant psychiatrist were conducted using criteria from DSM-IV, ICD-10 and the Royal College of Psychiatrists, Diagnostic Criteria for Psychiatric Disorders (DC-LD). DSWs and GPs were asked by telephone interview to provide information about (a) the usefulness of the checklists, (b) barriers to mental health care for this group, and (c) the outcomes for adults with ID as a result of their participation in this project. The results of the depression checklists were compared with the results from the Developmental Behaviour Checklists – Adults (DBC-A), a published screening tool for psychopathology in adults with ID.

Key Findings

The cause of ID was unspecified in 35% of participants; 14% had Down syndrome; 6% had an autism spectrum disorder. Co-morbid conditions were common: 61% had communication difficulties and 22% had sensory impairments. Eighty four percent of participants had sought help for mental health problems prior to participation in the study.

Fourty-three participants attended psychiatric assessment. The breakdown of diagnoses for this group on the basis of this assessment and the consensus process is shown in the following table.


Percentage of Sample

No psychiatric diagnosis  


Depressive disorder


Other psychiatric diagnosis (eg. Manic disorder, anxiety disorder, substance use disorder)


Pervasive developmental disorder


Behaviour disorder not related to psychiatric diagnosis


The checklists demonstrated good internal consistency and the following 4 subscales were identified: depression; anxiety; problem behaviours; and sleep disturbance. Checklist subsections most relevant to depression were: observed depressed mood; depressed thinking; loss of interest; social interaction and communication; appetite and weight loss; and general functioning. The more items from these sections reported on the DSW checklist, the higher the person’s score on the Depressive Subscale of the DBC-A: that is, response totals on these tools were highly correlated.

In general, DSW and GPs found the written report useful in providing a diagnosis and explanation for behavioural problems and recommended interventions that resulted in improvement in symptoms, behaviour and community participation for some of the participants. However many DSWs and GPs expressed concern about only one clinical consultation being provided, systemic difficulties in implementing recommendations, and lack of local services.

Implications for Policy and Practice

The general findings indicate much unmet mental health need in adults with ID. The findings also highlight the difficulties in general practice and mainstream mental health services in assessing and managing psychiatric disorder in adults with ID. There is a need for improved training of DSWs and GPs, access to specialised psychiatric support, and improved access to and co-ordination of services.

Future Directions

The checklists have been refined and are being used in another Beyond Blue project:  Determinants of Challenging Behaviour - and a longitudinal study of adults with Down syndrome. The checklist will soon be available from the Centre for Development and Disability Health Victoria website (

About the Researchers

We are psychiatrists and allied health professionals dedicated to improving the health and mental health of people with intellectual disabilities through research, clinical work and education and training of health professionals and support workers. We hope our work will lead to increased awareness, diagnosis and treatment of depression in people with intellectual disability and a consequent improvement in the quality of life for people with intellectual disabilities, their families, support workers and peers.

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