Epidemiology

Epidemiology

Stream Description

image - EpidemiologyEpidemiological studies of mental health and substance use disorders are vital to understanding the size and nature of the health challenges posed by these disorders. Our epidemiology stream aims to carry out epidemiological studies, both cross-sectional and longitudinal, examining the prevalence, correlates and natural history of mental health and substance use disorders. We also aim to carry out studies to refine and improve the ways in which mental health and substance use disorders are diagnosed and classified. In order to understand the distribution and impact of mental health and substance use disorders we undertake secondary analysis of existing epidemiological data sets, such as the Australian National Surveys of Mental Health and Wellbeing. Using innovative data analytic techniques we answer research questions such as:

  1.  What is the prevalence of alcohol use disorders in the general population and what sub-groups of the general population are at most risk of experiencing an alcohol use disorder?
  2. How has the prevalence of risky alcohol use and alcohol use disorders changed over time? How has the gender gap in risky alcohol use changed in more recent decades?
  3. What is the relationship between pre-existing mental disorders and the subsequent development of substance use disorders? How many people with a substance use disorder go on to develop a mental disorder
  4. What is the extent of the delay between the onset of a substance use disorder and the onset of treatment seeking? Does this delay differ depending on different demographic characteristic?
  5. Are the proposed changes to the DSM-IV diagnosis of alcohol use disorder valid?

Ongoing Projects

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2007 National Survey of Mental Health and Wellbeing (NSMHWB)

Funding Body: Australian Government Department of Health and Ageing
Description:

The 2007 National Survey of Mental Health and Wellbeing was conducted to provide updated evidence on the prevalence of mental illness in the Australian population, the amount of associated disability, comorbidity of mental disorders and comorbidity of mental disorders and chronic physical conditions, and the use of health services by people with mental disorders.The 2007 NSMHWB is a general household survey of the adult population aged 16-85 years, which was conducted by the Australian Bureau of Statistics from August to December 2007. This project aims to disseminate the findings of the 2007 NSMHWB regarding the prevalence and impact of mental and substance use disorders.

Project Contacts: A/Prof Tim Slade

A new generation of scales to measure mental and substance use disorders

A/Prof Philip Batterham, A/Prof Alison Calear.
Funding Body: NHMRC
Description:

The current program of research represents the largest study to apply Item Response Theory to improve the measurement of mental and substance use disorders. A series of new item banks have been developed using a highly systematic procedure for a range of disorders. These item banks precisely and validly target the full range of disorder severity experienced by community and clinical populations. From these item banks a series of data-driven static short forms and adaptive tests have been developed to efficiently measure disorders and screen for a diagnosis without compromising on precision. These short scales are valid with respect to existing scales used widely in the literature. Finally, these item banks were used to statistically equate a range of self-report scales to facilitate data comparisons and data pooling. Currently, eight scales for measuring psychological distress have been equated as well as multiple scales for measuring social anxiety disorder. These new instruments are freely available to researchers and clinicians.

Project Contacts: Dr Matthew Sunderland

Developing item banks and adaptive tests for child/adolescent mental and substance use disorders

A/Prof Philip Batterham, A/Prof Alison Calear, Dr Jill Newby
Funding Body: UNSW Medicine Neuroscience, Mental Health, and Addictions theme and SPHERE Mindgardens CAG.
Description:

Valid, accurate, and efficient ways to identify and monitor the severity of mental and substance use disorders forms the foundation of good clinical research and practice. Importantly, a life-course perspective for screening and monitoring disorders should appropriately capture changes in the manifestation of symptom indicators across age groups and facilitate easy comparison of data. A series of item banks to accurately measure a range of mental and substance use disorders has previously been developed and tested by the applicants using an adult community-dwelling population. However, given the heterogeneous nature of mental disorders across different age brackets, it is difficult and somewhat inappropriate to utilise these scales to accurately measure the presence and severity of disorders in a younger age group. The proposed project seeks to fill this gap by developing a series of age-specific item banks for children and adolescents (7-18 years). The proposed project will focus on developing item banks for an initial subset of disorders, including: social anxiety disorder, post-traumatic stress disorder/childhood trauma, obsessive-compulsive disorder, panic disorder, and problematic alcohol use. These item banks will be used to develop highly efficient screening scales as well as conversion tables to equate scores between the child/adolescent item banks with existing adult item banks to ensure quality data comparisons

Project Contacts: Dr Matthew Sunderland
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The Radar Project: identifying early warning signals on the pathways to alcohol use disorder

Funding Body: NHMRC
Description:

Globally, harmful alcohol use continues to be a major modifiable contributor to the burden of disease. In 2004/5, alcohol accounted for 27% (=$15.3 billion) of the Australian social costs of drug abuse, with alcohol use disorder (AUD), defined as a cluster of cognitive, behavioural and physiological symptoms indicating continued alcohol use despite significant problems, representing the most costly alcohol-related harm. Initiation of alcohol use is a rite of passage for many adolescents yet an alarming number drink at levels that put them at risk of harm. Such risky drinking patterns are strongly associated with the development of AUD and can trigger a cascade of lifelong adverse outcomes, such as mental disorders, suicide, other illicit drug use and antisocial behaviour as well as early onset of heart disease, stroke and cancer.

Australian and international adult population data indicate that the peak age of onset of AUD is 18 years, thus a deeper understanding of the adolescent experience is vital if we are to identify modifiable risk factors and intervene early in the developmental course of this disabling disorder. More broadly, despite spectacular improvements in the health of young children, indicators of adolescent health, including violence and injury associated with alcohol use, remain unchanged over the past 50 years. Through initiatives such as the recently established Lancet Commission on Adolescent Health and Wellbeing adolescents are now central in efforts to improve global health.

The proposed study responds to an urgent call for high quality, long-term prospective cohort studies to better understand the health burden of adolescent drinking. Critical unanswered questions include: How soon after drinking initiation do AUD symptoms begin to emerge? Which symptoms come first? Do the symptoms unfold in a predictable pattern? In what ways do the emerging symptoms interact with individual, peer, family and environmental risk factors to predict the transition to disorder?

The aim of the project is to conduct a world-first, intensive, longitudinal study of the developmental course of AUD across adolescence and young adulthood. The overarching hypothesis is that the timing, rate and order of symptom development will account for differences in the risk of developing AUD. The specific objectives are to 1) prospectively measure the presence, age at onset and temporal unfolding of AUD symptoms and 2) determine the individual, peer, family and environmental factors that, in the presence of early symptoms, predict transition to AUD.

Project Contacts: A/Prof Tim Slade

Completed Projects

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A dimensional-spectrum model of mental disorders: developing new assessments to improve the diagnostic validity of multiple mental disorders

Funding Body: NHMRC
Description:

The current program of research seeks to investigate new and emerging statistical models to develop accurate and efficient instruments that measure the latent relationship between internalising (eg. depression, anxiety), externalising (eg. substance use, anti-social and conduct disorder) and thought disorders (eg. psychosis).

A growing body of empirical evidence has questioned the validity of categorical diagnostic instruments. Converging lines of evidence suggest that models of psychopathology that measure multiple disorders through the use of broad dimensional spectra offer a significant improvement to psychiatric research and clinical practice. This model is commonly referred to as a dimensional-spectrum model. In order to facilitate the use of dimensional models to measure the broad spectra of psychopathology there is a growing need for new assessment tools that measure the dimensionality of psychiatric disorders. Previously, dimensional instruments for individual disorders have been developed however no study has examined the possibility of constructing a tool that measures the complex latent relationship between putatively distinct disorders using a dimensional-spectrum model. Advances in measurement theory, particularly multidimensional Item Response Theory (IRT), offer innovative ways to measure broad dimensional constructs. These methods can be utilised for the development of efficient and accurate diagnostic tools through the use of computerised adaptive testing.

The current research program aims to develop and test an innovative and novel approach for measuring psychiatric disorders in community and clinical populations using a dimensional-spectrum model as the guiding theoretical framework.

Project Contacts: Dr Matthew Sunderland
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Alcohol use disorders in young adults: "Youthful epidemic" or diagnostic bias?

Prof Bob Kruger
Funding Body: National Health and Medical Research Council
Description:

Epidemiological studies show that 1 in 5 Australians aged 18-24 are diagnosed as having an alcohol use disorder (AUD). However, there is evidence to suggest that young adults may interpret the diagnostic criteria differently to older adults. The current study aimed to validate the alcohol use disorder criteria in younger populations through the use of novel cognitive interviewing techniques. Results showed that while young adults understand some of the AUD diagnostic criteria as intended (e.g. tolerance), other criteria are misinterpreted, resulting in an over-estimation of the prevalence of alcohol use disorders in this age group.

Project Contacts: A/Prof Tim Slade
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Diagnosing major depression in older Australian adults: Is there evidence for age-related bias?

Dr Philip Batterham, Heather Buchan
Funding Body: National Health and Medical Research Council
Description:

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.

Project Contacts: Dr Matthew Sunderland

How do we translate Research Investments into Clinical Outcomes in Australian Mental Health Services?

Erica Crome
Funding Body: Macquarie University Research Development Grant
Description:

Whilst there is growing evidence about the barriers to evidence-based practice in mental health treatment, we understand little about what information clinicians actually use, or their ongoing information needs. This project aims to broaden the typical focus on individual professions and barriers to implementation, and develop an understanding of the information needs of all mental health clinicians in Australia to optimise the dissemination of research into clinical practice.

Project Contacts: Dr Matthew Sunderland
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Secondary traumatic stress among alcohol and other drug workers

Dr Claudia Sannibale, Prof Ann Roche, Ms Philippa Ewer
Description:

There is a growing literature documenting the high prevalence of trauma exposure and post traumatic stress disorder (PTSD) among people with alcohol and other drug (AOD) use disorders. Indeed, in this population trauma exposure is almost universal and up to one-third have current PTSD. Studies have shown that individuals who are involved in the assessment and treatment of traumatised clients may be at risk of secondary traumatic stress (STS). STS has been described as particular behaviours, emotions and stress that result from helping or wanting to help traumatised individuals. STS has been referred to as an occupational hazard for those working with trauma survivors, however, limited research has been conducted in the area. To our knowledge only one US study has examined STS among the AOD workforce. They found that 19% of the AOD workers they assessed met criteria for current STS. While STS has been explored among the AOD workforce in the US, the degree to which it is suffered by AOD workers in Australia is unknown. The aims of the study are to address two research questions:

1) What is the prevalence of secondary traumatic stress (STS) among AOD workers in Australia?

2) What factors are associated with the presence of STS and its severity (e.g., professional experience and training; a personal history of trauma exposure and PTSD)?

Project Contacts: A/Prof Katherine Mills

Untangling co-morbidity: substance use and mental health in young Australians

Funding Body: APA and Rotary Health
Description:

This project investigated the co-morbidity of depression, anxiety and substance use in young Australians. The program of research utilised large epidemiological datasets and prevention trial data to map the developmental sequence of anxiety and mood disorders and alcohol use in the Australian population.

Two studies examined data collected as part of the 2007 Australian National Survey of Mental Health and Wellbeing. Study one investigated the impact of early onset anxiety disorders on age of first use of alcohol, while study two investigated the impact of early onset mood disorders on first use of alcohol. These studies are the first epidemiological investigations to model the impact of early onset anxiety and mood disorders on age of first alcohol use in a general population sample. Early onset anxiety and mood disorders were found to act as unique risk factors for first alcohol use, particularly after the age of 14 years. Significant interactions with developmental timing highlight the need to take into account age when examining the origins of the comorbidity between alcohol use and mood disorders. Different patterns were also observed in relation to individual anxiety and mood disorders.

Study three examined the developmental trajectories of emotional symptoms in a sample of adolescents followed from 13 to 16 years old. Latent class growth analysis uncovered four different trajectories of emotional symptoms. Adolescents whose emotional symptoms remained relatively high-stable across the study period were found to be using alcohol at higher rates at age 16 years, compared to their peers. This is the first time this has been examined in an Australian longitudinal sample.

Study four modelled the concurrent development of emotional symptoms and alcohol use in a cohort of 1,517 early adolescents over two years. Parallel latent growth modelling investigated whether growth in emotional symptoms was related to growth in alcohol use, and vice versa. Higher initial symptom levels predicted increasing alcohol use frequency. There was no relationship between growth in symptoms, or growth in alcohol use in a large sample of early adolescents from the general population.

Project Contacts: Dr Louise Birrell

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