Claire Gallagher

The differential effects of BMI trajectories on the risk of anxiety and depression

Supervisors: Professor Bircan Erbas, Professor Shyamali Dharmage, Dr Raisa Cassim, Professor Jane Perkis

The widespread prevalence of anxiety and depression is of global concern, as these common mental disorders are among the leading causes of disability and are major contributors to the global burden of disease. Research exploring possible causes of this growing public health problem has identified excess adiposity as one contributing factor; with numerous studies finding obesity is associated with an increased risk of depression and likely an increased risk of anxiety.

However, much of the research to date has been based on cross-sectional evidence and longitudinal studies have typically only measured BMI at one or two time points. Considering that weight varies throughout the life course, the assessment of BMI trajectories over time is a more favourable approach and could offer greater insights into the aetiology of mental health, by allowing researchers to explore how distinct patterns in the timing and duration of obesity exposure differentially influence the risk of anxiety and depression. Such an approach also allows for the identification of sensitive periods over the life course during which the effects of excess adiposity are most harmful and thus, research exploring the associations between BMI trajectories and anxiety and depression risk could help better inform the design and targets of intervention strategies aimed at reducing the growing burden of mental disorders.

Therefore, this research project will utilise longitudinal data from several cohort studies to model BMI trajectories over various stages of life and will explore their associations with subsequent measures of anxiety and depression. We will also explore whether sex, green space, diet and physical activity modify the associations observed between BMI trajectories and mental health outcomes.

PhD scholarship and funding body: Research Training Program Scholarship, The University of Melbourne