Melbourne School of Psychological Sciences - Research Publications
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ItemAssociations between diet quality and anxiety and depressive disorders: A systematic review(Elsevier, 2023-12-01)Background: Emerging evidence suggests that a healthier diet is associated with a reduced risk for depressive symptoms. However, the relationships between diet quality and clinical depression and anxiety have not been established. This systematic review is the first to examine whole-of-diet associations in cohorts with diagnosed depression and/or anxiety disorders. Methods: Literature searches captured 44 studies reporting on diet quality (22 cross-sectional, 12 prospective, seven combining cross-sectional/longitudinal data) OR using a dietary intervention in adults with depression and/or anxiety diagnoses (3 RCTs). A best-evidence synthesis of 25 observational studies of higher methodological quality was conducted. Results: There was strong evidence that adherence to a Mediterranean diet was associated with lower depression incidence in prospective studies. Level of adherence to national dietary guidelines was not consistently associated with anxiety and depression. Studies which examined other dietary quality measures reported conflicting or limited evidence in relation to both anxiety and depression, with considerably fewer studies reported in anxiety. Some dietary interventions showed promising findings in relation to improvements in depression/anxiety outcomes, however, a range of methodological limitations warrant further consideration. Limitations: Heterogeneity across studies was high which limited the ability to compare findings and precluded meta-analysis. Conclusions: High-quality prospective studies generally support evidence that increased adherence to a Mediterranean diet may be a cost-effective and safe adjunct to existing therapies for clinical depression, which is supported by the findings of several dietary interventions.
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ItemAssociations between early life stress and anterior pituitary gland volume development - A novel index of long-term hypothalamic-pituitary-adrenal axis functioning(WILEY, 2021-01-01)Previous research has established associations between early life stress (ELS) and altered pituitary gland volume (PGV) growth during adolescence. The pituitary gland, however, is composed of an anterior and a posterior lobe with distinct histological and neuroendocrinological properties. While the anterior (but not posterior) pituitary gland is directly involved in the hypothalamic-pituitary-adrenal axis (HPAA) stress response, no studies have examined the effects of ELS on anterior PGV (aPGV). The present study investigated whether previously reported associations between ELS and PGV development during adolescence were driven by aPGV versus posterior PGV (pPGV). Ninety-one adolescents (49 males) were included from a longitudinal, community-based adolescent development study investigating risk for psychopathology. ELS (maternal affective behavior, childhood maltreatment, stressful life events) was assessed during early adolescence. Participants underwent two waves of structural magnetic resonance imaging during mid- and late-adolescence, and aPGV and pPGV were manually traced. Regression analyses showed that childhood maltreatment predicted greater aPGV growth in females. This finding was stronger than that previously reported for PGV. No associations were found between ELS and pPGV development. Neither aPGV nor pPGV changes mediated associations between ELS and psychopathology. Results suggest that ELS may accelerate aPGV (but not pPGV) growth throughout adolescence. Investigating the development of aPGV, rather than PGV, represents a novel approach to studying the effects of stress on HPAA functioning.
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ItemBugs and Brains, the Gut and Mental Health Study: a mixed-methods study investigating microbiota composition and function in anxiety, depression and irritable bowel syndrome(BMJ PUBLISHING GROUP, 2021)INTRODUCTION: Research has highlighted relationships between the micro-organisms that inhabit our gastrointestinal tract (oral and gut microbiota) with host mood and gastrointestinal functioning. Mental health disorders and functional gastrointestinal disorders co-occur at high rates, although the mechanisms underlying these associations remain unclear. The Bugs and Brains Study aims to investigate complex relationships between anxiety/depression and irritable bowel syndrome (IBS) in two ways. First, its primary component will compare the gut and oral microbiota in females with anxiety/depression and/or IBS relative to controls, and investigate underlying physiological, endocrine and immune factors, as well as associations with diet and psychosocial factors. In an ancillary component, the study will also investigate gastrointestinal and mental health symptoms in a larger sample, and explore relationships with diet, exercise, oral health, substance use, medical history, early life adversity and psychosocial factors. METHODS AND ANALYSIS: The Bugs and Brains Study aims to recruit 160 females to the primary component: (1) 40 controls; (2) 40 participants with a depressive/anxiety disorder, but no IBS; (3) 40 participants with IBS, but no depressive/anxiety disorder and (4) 40 participants with both depressive/anxiety disorder and IBS. Participation is completed within 1 month, and involves comprehensive questionnaires, anthropometrics, a diagnostic clinical interview, collection of two saliva samples, and stool, urine and hair samples. This study aims to use a systems biology approach to characterise oral and gut microbial composition and function using 16S rRNA gene sequencing and nuclear MR spectroscopy. As part of the ancillary component, it will collect questionnaire data from 1000 participants aged 18-40 years, capturing mental health, gastrointestinal health, oral health, diet and psychosocial factors. ETHICS AND DISSEMINATION: Approval was granted by the University of Melbourne Human Research Ethics Committee (#1749221). All participants voluntarily provided informed consent. Results will be published in peer-reviewed journals and presented at scientific conferences.