Research projects

Depression in people with intellectual disability: An evaluation of a staff administered treatment program

Principal Researchers

Dr Teresa Iaconoa, Ms Stella Koritsasa, Associate Professor Robert Davisa, Dr David Hamiltonb


a Centre for Developmental Disability Health Victoria, Monash University

b School of Psychology, Deakin University



Award Type

Beyond Blue Victorian Centre of Excellence

Project completion year


Project brief

People with intellectual disability (ID) have a higher prevalence of depression than the general population.  ID is often accompanied by impaired communication, especially in cases of severe ID.  This can lead to difficulties in diagnosis of mental health disorders, particularly in determining whether challenging or anti-social behaviours are indicative of such disorders.

This study aimed to determine the extent to which mental health problems, physical health, adaptive functioning and level of communication contribute to the severity of challenging behaviours in adults with ID.  Information was collected via observation of the person with ID, interviews with direct support workers and completion of questionnaires by those workers.

The study included 61 participants (39 male and 22 female) with ID.  The average age of participants was 37 years.  According to reports by direct support workers, 5 per cent of participants had a mild ID, 33 per cent had a moderate ID and 8 per cent had a severe ID.  The level of ID was unknown for 54 per cent of participants. 

The project also aimed to build on a depression checklist developed in a 2006 Beyond Blue project: Psychological Assessment Schedule for Adults with Developmental Disabilities, Developmental Behaviour Checklist for Adults (DBC-A).

Key findings

The research did not find a relationship between depression and challenging behaviour as measured by the checklist.  However, almost half of the participants who met criteria for psychiatric cases also scored high on the depressive subscale of the DBC-A, therefore suggesting that depression is a significant problem in people who show emotional and behavioural disturbances.

A preliminary analysis of health data in this study indicated many people with ID who display challenging behaviour also have significant health conditions that are likely to influence their behaviour.  The main predictors of challenging behaviour were scales for self-absorbed, anxiety, sensory function and Total Behaviour Problem Score.

While the research did not find a correlation between depression and challenging behaviour, this does not necessarily suggest a lack of association between these factors.  It may indicate that people with ID are limited in their ability to express certain behaviours associated with diagnosis of depression in the general population.  The results suggest that using challenging behaviour to assess mental health disorders in people with ID is a complex issue, requiring multidisciplinary assessments.

Implications for policy, practice and further research

People who have ID and demonstrate challenging behaviours should be assessed for mental health, in particular for anxiety and self-absorbed focus.  Comprehensive health assessments should also be included in any assessment of challenging behaviour.  Given that some of the challenging behaviours were found to have been displayed for sensory purposes, health practitioners should look at other ways people with ID can obtain sensory stimulation.

General practitioners may consider routine use of the Torr checklist to help diagnose depression in people with ID.


Torr, J., Iacono, T., Graham, M., Galea, J., Tonge, B., Einfeld, E. et al. Diagnosis and Treatment of Depression in Adults with Intellectual Disability through General Practitioner and Psychiatric Collaboration.

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