Abstract
Background: Depression affects 5% of adults worldwide. Lifestyle changes are increasingly being investigated as adjunctive treatment options to address major depressive disorder (MDD). There is a need to assess the effectiveness and feasibility of dietary interventions for treating MDD.Methods: The research was guided by a pragmatic perspective, emphasizing real-world problems and solutions. To address the research questions, five studies employing a mixed methods approach were conducted. Study One and Two assessed the literature addressing the use of dietary interventions in clinically depressed populations, and the potential to modulate the microbiota through dietary change. A qualitative study (Study Three) examined barriers and enablers to dietary change through the eyes of individuals living with MDD. A cross-sectional study (Study Four) evaluated factors that may influence the relationships between diet and depression. While a feasibility randomised controlled trial (Study Five) tested the feasibility of a legume-based dietary intervention as an adjunctive treatment.
Results: Dietary interventions show promise as adjunctive treatments for managing MDD, with careful modulation of the microbiome a possible target for future treatments. Barriers to dietary change were found to include low motivation and financial constraints. Social connections were identified as both a barrier and an enabler depending upon the individual’s circumstances. For a university student population, food insecurity and physical activity correlated with depression accounting for 11% and 9% of the variance seen in depressive scores respectively. Diet quality did not correlate with depression scores in this cohort. Finally, a legume intervention resulted in similar changes in mood to a healthy food intervention and caused no increase in gastrointestinal symptoms.
Conclusions: The research highlights the multifaceted nature of MDD and the importance of integrating lifestyle and contextual factors into treatment approaches. Dietary interventions were found to augment the efficacy of traditional treatments, while food insecurity emerges as a significant barrier to recovery, particularly among young adults. Although social connections and physical activity are commonly promoted as protective factors, their relationships with MDD were inconsistent, suggesting the need for more nuanced understanding and the need to address individual circumstances when treating MDD. The research also revealed a lack of belief and understanding in the effectiveness of dietary strategies among individuals living with MDD, underscoring the need for targeted education and support. A legume-based dietary intervention was identified as a feasible, low-cost strategy with strong potential for future clinical trials. These findings support the development of holistic and individualised treatment plans and development of practice guidelines and policy across clinical and community settings.
| Date of Award | 2025 |
|---|---|
| Original language | English |
| Supervisor | Michelle Minehan (Supervisor), Cathy KNIGHT-AGARWAL (Supervisor) & David PYNE (Supervisor) |