Despite the now extensive evidence for health behaviours, such as diet and physical activity, as risk factors and treatment targets for mental disorders, lifestyle-based mental health care is not currently integrated into routine practice in Australia, or worldwide. Nor are lifestyle factors, such as diet, targets of public health messaging or policy to reduce the burden of mental disorders.
For these changes to occur, policy makers need evidence of how much of the mental disorder burden could be avoided if lifestyle behaviours could be improved at the population level, and if lifestyle-based mental health care was used in practice. This would then provide evidence of the cost and health benefits to the population if lifestyle factors were a target of public policy, public health messaging, and mental health care.
The overarching aim is to have lifestyle factors recognised and quantified as contributors to the global burden of mental disorders. Within this aim, the GLAD taskforce will establish how much of the mental disorder burden would be avoided if lifestyle factors, such as diet, were improved at the population level. This project draws on the Global Burden of Disease (GBD) Study, the most comprehensive epidemiological study worldwide. The GBD provides high quality morbidity data for major diseases and risk factors.
Currently, estimates for population attributable risks/fractions (PAFs) – the proportion of an illness averted if a specific exposure was eliminated – are available for many lifestyle risk factors, but only in relation to physical disorders and not for common mental disorders. The GLAD Taskforce aims to address this key gap. With the contribution of member studies, the GLAD Taskforce will generate critical evidence, including PAFs, that the GBD needs to integrate lifestyle factors as risk-outcome pairs for common mental disorders and the necessary evidence policy makers need to know whether integrating lifestyle mental health care into standard practice represents a good return on investment at a national and international level.
Purpose of the GLAD Taskforce
Common mental disorders present a major and growing global public health challenge, and there is now extensive evidence for health behaviours, such as diet and physical activity, as a risk factor and treatment target for common mental disorders, particularly depression. We believe that a global effort is required to reduce the global burden of disease attributable to common mental disorders by targeting these risk factors.
The aim of the GLAD Taskforce is to investigate the contribution of lifestyle risk factors to common mental disorders globally, by sex and over time. Our initial aim is to develop evidence for diet as a contributor to depression, in a format that affords integration into the Global Burden of Disease (GBD) study. Ultimately, this activity will allow researchers and policy makers to calculate how much of the population burden for common mental disorders could be averted by targeting specific lifestyle factors across different settings, sexes and age groups, referred to as population attributable fractions (PAFs). Quantifying these PAFs will be the first step in supporting the necessary changes to food policy, public health and clinical practice, that will improve outcomes for people living with, or at risk of, depressive illness.
What the GBD team needs in order to generate these estimates
We are initially looking for existing studies on adults that have the following dietary and common mental disorder data available:
Exposure – Food frequency questionnaires, or data specifically on:
- Diet low in fruits
- Diet low in vegetables
- Diet low in legumes
- Diet low in whole grains
- Diet low in nuts and seeds
- Diet low in milk
- Diet high in red meat
- Diet high in processed meat
- Diet high in sugar-sweetened beverages
Outcome – validated measures of one or more of the following:
- Major depressive disorder
- Dysthymia
- Depressive symptoms
- Anxiety (any/all subtypes)
- Anxiety symptoms
Other variables including age, sex and year of outcome measurement.
While the first activities of the Taskforce will focus on diet, future steps will address physical activity, smoking, and sleep. So, if you have data available on any of these, you can still participate in the GLAD.
Your role
The GLAD Taskforce uses a somewhat different approach to other collaborative studies – you (the member study) will remain in control of your own data, and so all the ethical and legal obligations are hosted by the institution where the initial agreements were approved. A similar approach has been undertaken by the MRC Epidemiology Unit at the University of Cambridge. This process has been recommended to us by the GBD team at the Institute of Health Metrics and Evaluation.
If you are interested in participating in the Taskforce, we (the project team) will provide you with a terms of reference document containing the details of your involvement, a data analysis plan (approved by the GBD and registered on Open Science Framework) and ongoing statistical support. You will follow the plan and publish a peer reviewed paper containing your findings. We will then apply your published data, and that of other Taskforce members who will concurrently do the same activity, to conduct meta-analyses – the results of which will be sent to the GBD. At no point during this process do we require identifiable data.
However, if you agree to make your data available to the GLAD Taskforce, all data transfer agreements and policies will be held and approved by your own institution, and members of the Taskforce will abide by all relevant policies.
If you are interested in participating in GLAD, please read and sign the terms of reference document and return to GLAD-info@deakin.edu.au
Our role
We will provide data analysis plans and statistical advice. Our preferred analysis software is Stata, and, if needed, we will provide example analysis code to fit relevant models. However, any analysis software is acceptable, provided you are able to write your own code or adapt the code provided. To ensure consistency in the published papers, we request that you provide the executive committee with the opportunity to review and provide feedback on your drafts, and together we will discuss authorship/acknowledgements as the need arises.
After you have published the relevant paper, we will conduct the systematic review and meta-analyses, to pool the estimates needed by the GBD. Members of the GLAD Taskforce will be invited to contribute to this review, and to contribute to the screening of studies and data extraction. To reduce bias, GLAD members will not be allowed to evaluate the risk of bias of their included studies.
Once the meta-analysis has been published, we will approach the GBD to lobby for lifestyle factors to be included as risk-outcome pairs for mental disorders, starting with diet and depressive illnesses.
