Assessing the role of diet and nutrition in depression risk

Background:

Depression is highly prevalent, frequently recurrent, and currently affects an estimated 185 million people worldwide, with cases projected to more than double by 2040. Depression is a complex disorder, arising from interactions between genetic, biological, psychological, and environmental factors. Identifying modifiable risk factors for depression is therefore an urgent priority for its prevention and management.

There is growing evidence that depression risk could be reduced through lifestyle changes. Diet and nutrition play a vital role in maintaining optimal brain function and are well established as key factors in preventing major chronic conditions (e.g., diabetes), which are associated with an increased risk of depression. However, the association between diet and depression is unclear. In particular, the onset of subclinical or early-stage depression may lead to a deterioration in diet quality, making it difficult to rule out reverse causation in studies with relatively short follow-up. Furthermore, the biological pathways through which diet may influence depression risk remain poorly understood.

This project aims to address these knowledge gaps through evidence synthesis and analyses of large-scale cohort data (e.g., UK Biobank), with the goal of clarifying the role of diet and nutrition in depression risk and informing effective prevention strategies.

Study 1: What works - comparative effects of dietary interventions on risks of depression

This study will synthesise evidence from clinical trials through a systematic review and network meta-analysis to evaluate the comparative effectiveness of dietary interventions (e.g., Mediterranean, plant-based, ketogenic, and low glycaemic index diets) on depressive symptoms and risk reduction. It will also examine how specific intervention characteristics, such as duration, delivery mode, and participant adherence, modulate these effects.

Study 2: How it works - the mediating factors

Using large-scale population-based cohorts such as the UK Biobank, this study will investigate associations between dietary patterns and depression severity. Analyses will focus on established healthy dietary patterns (e.g., the Mediterranean diet) and UK-specific dietary patterns previously identified by Gao et al. (2022).

Study 3: How best to apply it - optimise dietary interventions for depression prevention

Effective prevention requires that individuals not only adopt but also sustain healthy dietary behaviours over time. This study will conduct a systematic review of trials and implementation studies to identify strategies that improve adherence to dietary interventions aimed at reducing depression risk or symptoms. Quantitative and qualitative findings will be integrated to determine what works, for whom, and under what circumstances, providing evidence-based recommendations for designing scalable and sustainable dietary strategies for depression prevention.

Preferred applicant background/skills:

This project will involve secondary analyses of large and detailed observational datasets. The student will be expected to conduct statistical analyses using appropriate software (e.g., Stata, R) and apply longitudinal analytic techniques. The project is best suited to a candidate with postgraduate-level training in epidemiology, statistics, or public health and a strong interest in nutrition and mental health research.