title: Longitudinal diet quality is not associated with depressive symptoms in a cohort of middle-aged Australian women.
abstract: There is increasing evidence for the role of nutrition in the prevention of depression. This study aims to describe changes in diet quality over 12 years among participants in the Australian Longitudinal Study on Women's Health in relation to changes in depressive symptoms. Women born between 1946 and 1951 were followed-up for 12 years (2001-2013). Dietary intake was assessed using the Dietary Questionnaire for Epidemiological Studies (version 2) in 2001, 2007 and every 2-3 years after that until 2013. Diet quality was summarised using the Australian Recommended Food Score (ARFS). Depressive symptoms were measured using the ten-item Centre for Epidemiologic Depression Scale at every 2-3-year intervals during 2001-2013. Linear mixed models were used to examine trends in diet quality and its sub-components. The same model including time-varying covariates was used to examine associations between diet quality and depressive symptoms adjusting for confounders. Sensitivity analyses were carried out using the Mediterranean dietary pattern (MDP) index to assess diet quality. Minimal changes in overall diet quality and its sub-components over 12 years were observed. There was a significant association between baseline diet quality and depression (β=-0·24, P=0·001), but this was lost when time-varying covariates were added (β=-0·04, P=0·10). Sensitivity analyses showed similar performance for both ARFS and MDP in predicting depressive symptoms. In conclusion, initial associations seen when using baseline measures of diet quality and depressive symptoms disappear when using methods that handle time-varying covariates, suggesting that previous studies indicating a relationship between diet and depression may have been affected by residual confounding.
authors.affiliation: 1School of Medicine and Public Health,University of Newcastle,Callaghan,NSW 2308,Australia.
authors.forename: Jun S
authors.initials: JS
authors.lastname: Lai
authors.affiliation: 2Hunter Medical Research Institute,New Lambton,NSW 2305,Australia.
authors.forename: Christopher
authors.initials: C
authors.lastname: Oldmeadow
authors.affiliation: 1School of Medicine and Public Health,University of Newcastle,Callaghan,NSW 2308,Australia.
authors.forename: Alexis J
authors.initials: AJ
authors.lastname: Hure
authors.affiliation: 1School of Medicine and Public Health,University of Newcastle,Callaghan,NSW 2308,Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: McEvoy
authors.affiliation: 1School of Medicine and Public Health,University of Newcastle,Callaghan,NSW 2308,Australia.
authors.forename: Julie
authors.initials: J
authors.lastname: Byles
authors.affiliation: 1School of Medicine and Public Health,University of Newcastle,Callaghan,NSW 2308,Australia.
authors.forename: John
authors.initials: J
authors.lastname: Attia
mesh_terms: D001315:Australia / Q000453:epidemiology; D003863:Depression / Q000453:epidemiology*; D004032:Diet; D002149:Energy Intake; D005260:Female; D005500:Follow-Up Studies; D063427:Food Quality; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D008875:Middle Aged; D011446:Prospective Studies; D011569:Psychiatric Status Rating Scales; D011795:Surveys and Questionnaires; D016387:Women's Health
keywords: ARFS Australian Recommended Food Score; DQES v2 Dietary Questionnaire for Epidemiological Studies version 2; Depressive symptoms; Diet quality; Diet trends; Females; Longitudinal studies; MDP Mediterranean dietary pattern