Epidemiological studies have consistently indicated that the prevalence of depression decreases with increasing age. Researchers have debated whether this finding is a real age-dependent decline or an artefact of sampling and assessment. This study seeks to use statistical methods and cognitive interviewing to investigate the potential for age-related bias in the criteria for major depression. The study will make recommendations to improve the diagnostic methods used diagnose and treat major depression in the old age.
Dr Philip Batterham
College of Medicine, Biology and Environment, ANU
Prof Gavin Andrews
School of Psychiatry, UNSW
Dr Louise Mewton
School of Psychiatry, UNSW
Nationally representative surveys conducted in Australia and abroad provide valuable information regarding the pervasiveness, risk factors, and service use associated with major depressive disorder (MDD) in the community. This information is utilised by mental health policy makers to direct limited funding towards subgroups of the population that would benefit from targeted prevention and treatment programs. However, there is significant controversy in the literature regarding the accuracy of the DSM-IV criteria when estimating the prevalence of MDD in older adults.
To address the pressing need to clarify the validity of mental health assessment methods used to diagnose DSM-IV MDD in older individuals (aged 65+) within the Australian population.
The project will utilise a two stage design to examine the extent of age-related bias in the current Australian prevalence estimates of MDD. The first stage will utilise a statistical technique known as differential item functioning to investigate the presence and extent of bias in the DSM-IV MDD criteria, operationalised in the 2007 Australian National Survey of Mental Health and Wellbeing. The second stage will further investigate the source of bias in older Australian adults through the use of an expert review of the diagnostic criteria and cognitive interviewing in a sample of older Australians.
The project successfully obtained approval from UNSW HREC.
The first stage of the study is now complete. Several analyses of the general population survey data have been conducted and have resulted in four published manuscripts investigating various age-related changes and biases inherent in the diagnostic criteria for mental disorders. Three manuscripts are currently submitted or in preparation and will be submitted for publication shortly.
The second stage of the study design is also complete and the expert review of the diagnostic criteria is finished. The data from the expert review have been analysed and incorporating into a cognitive interview that seeks to investigate the thought processes of older adults when they answer questions about diagnostic symptoms of depression. Data collection for the cognitive interview component of the study has now finished and the interviews have been transcribed and entered into qualitative analysis software. The data will be analysed and written up over the next three months.
Buchan, H., Sunderland, M.,Carragher, N., Louie, E., Batterham, P., Slade, T. Investigating factors that bias the reporting of depression symptomatology among older Australian adults. American Journal of Geriatric Psychiatry, submitted.
Sunderland, M.,Anderson, T. M., Sachdev, P. S., Titov, N., Andrews, G. Lifetime and current prevalence of common DSM-IV mental disorders, their demographic correlates, and association with service utilisation and disability in older Australian adults.Australian and New Zealand Journal of Psychiatry, in press.
Buchan, H., Sunderland, M., Carragher, N., Batterham, P., Slade, T. (2014). Investigating age-related differences in responses to the screening items of diagnostic instruments in three national surveys. Journal of Affective Disorders, 152-154(1), 229-236.
Mewton, L., Sachdev, P., Anderson, T., Sunderland, M., Andrews, G. Demographic, clinical and lifestyle correlates of subjective memory complaints in the Australian population. American Journal of Geriatric Psychiatry, in press.
Sunderland, M., Carragher, N., Buchan, H., Batterham, P. J., Slade T. Comparing profiles of mental disorder across birth cohorts: Results from the 2007 Australian National Survey of Mental Health and Wellbeing. Australian and New Zealand Journal of Psychiatry, in press.
Sunderland, M., Slade, T., Carragher, N., Batterham, P., Buchan, H. (2013). Age-related differences in internalizing psychopathology amongst the Australian general population. Journal of Abnormal Psychology, 122(4), 1010-1020.
Conference presentations and Posters:
Buchan, H., Sunderland, M., Carragher, N., Batterham, P., and Slade, T. (2014) Expert review of the DSM-5 criteria for diagnosing major depression in older Australian adults. Society for Mental Health Research annual conference, Adelaide, December.
Buchan, H. (2013) Assessing mental health in old age: investigating bias in the diagnostic instruments. Australasian society for psychiatric research 2013 conference, Melbourne, December.
Buchan, H., Sunderland, M., Carragher, N., Batterham, P. and Slade, T. (2013) Assessing mental health in old age: Investigating bias in the diagnostic instruments. NDARC Annual Symposium, Sydney, 4 September.
Sunderland, M.(2013). Change across ten year age bands in the level of internalizing psychopathology amongst the Australian general population. The 14th International Congress of the IFPE, Leipzig, Germany, June.
The results of the proposed research project will have broad policy, clinical and public health implications. Specifically, prevalence estimates generated by epidemiological studies are critical to mental health policy makers who are responsible for directing funding to future treatment and prevention plans. In clinical settings, the DSM-IV diagnostic criteria is applied consistently across varying adult ages without complete knowledge that the criteria is valid for assessing old age depression. Furthermore, this research will provide evidence of validity to future studies that aim to examine the complex relationship between MDD and comorbid disorders amongst older Australians.