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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ItemDevelopment of morning-eveningness in adolescence: implications for brain development and psychopathology(WILEY, 2023-03)BACKGROUND: Morning-evening preference is defined as an individual's preference for a morning- or evening-oriented rhythm. Across adolescence, a preference for eveningness becomes more predominant. Although eveningness is cross-sectionally associated with internalizing and externalizing psychopathology, few studies have examined developmental changes in eveningness and its potential biological substrates. Here, we investigated the longitudinal relationships among the trajectory of eveningness preference, internalizing and externalizing psychopathology and white matter development, across adolescence. METHODS: Two-hundred and nine adolescents (49% male) were assessed longitudinally at four separate time points between 12 and 19 years of age. Morning-evening preference and internalizing and externalizing symptoms were assessed at each time point. Diffusion-weighted images were acquired on a subset of participants at the final two time points to estimate changes in global mean fractional anisotropy (FA). Linear mixed models were performed to estimate the change in eveningness over time. A series of linear regression models assessed the influence of change in eveningness on psychopathology and white matter development at age 19. RESULTS: Across the sample, a preference for eveningness became more predominant by 19 years of age. Greater individual-level change towards eveningness significantly predicted greater severity in externalizing, but not internalizing, symptoms at 19 years of age. In contrast, change in psychopathology from 12 to 19 years of age was not associated with morning-eveningness at age 19. A change towards eveningness predicted an attenuated increase in FA between 17 and 19 years of age. CONCLUSIONS: This study suggests that developmental changes in morning-evening preference may predict both neurodevelopmental and psychological outcomes in adolescents.
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ItemNo Preview AvailableHarsh and Inconsistent Parental Discipline Is Associated With Altered Cortical Development in Children(ELSEVIER, 2022-10)BACKGROUND: A growing body of evidence suggests that parenting behaviors may affect child mental health via altering brain development. There is a scarcity of research, however, that has investigated associations between parenting behavior and brain structure using longitudinal magnetic resonance imaging. This study aimed to investigate associations between parenting behaviors and structural brain development across the transition from childhood to adolescence. METHODS: Participants were 246 children who provided 436 magnetic resonance imaging datasets covering the age range from 8 to 13 years. Parents (94% mothers) completed self-report measures of parenting behavior, and both children and parents reported on child mental health. Factor analysis was used to identify dimensions of parental behavior. Linear mixed-effects models investigated associations between parenting behaviors and age-related change in cortical thickness and surface area and subcortical volume. Mediation models tested whether brain changes mediated associations between parenting behaviors and changes in internalizing/externalizing symptoms. RESULTS: Hypothesized associations between parenting and amygdala, hippocampal, and frontal trajectories were not supported. Rather, higher levels of parent harsh/inconsistent discipline were associated with decreases in surface area in medial parietal and temporal pole regions and reduced cortical thinning in medial parietal regions. Some effects were present in female but not male children. There were no associations between these neurodevelopmental alterations and symptoms. CONCLUSIONS: This study provides insight into the links between parenting behavior and child neurodevelopment. Given the functions of implicated regions, findings may suggest that parental harsh/inconsistent discipline affects the development of neural circuits subserving sensorimotor and social functioning in children.
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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.