Dietary patterns and depressive symptoms over time: examining the relationships with socioeconomic position, health behaviours and cardiovascular risk.
BACKGROUND
Recent research suggests that diet quality influences depression risk; however, a lack of experimental evidence leaves open the possibility that residual confounding explains the observed relationships. The aim of this study was to document the cross-sectional and longitudinal associations between dietary patterns and symptoms of depression and to undertake a detailed examination of potential explanatory factors, particularly socioeconomic circumstances, in the diet-depression relationship.


METHODS
Data were drawn from the Personality and Total Health (PATH) Through Life Study, a longitudinal community study following three age cohorts (20+; 40+; 60+yrs) from south-eastern Australia over three assessment periods (n=3663). Regression analyses evaluated the cross-sectional and longitudinal relationships between dietary patterns, depressive symptoms, age, detailed measures of socioeconomic circumstances, other health behaviours, and cardiovascular risk factors.


RESULTS
The lowest tertile of prudent (healthy) dietary pattern and the highest tertile of western (unhealthy) dietary pattern were associated with an increased likelihood of depressive symptoms. However, these contemporaneous associations were explained by adjustment for detailed measures of socioeconomic circumstances and physical activity. In prospective analyses, lower scores on the healthy dietary pattern and higher scores on the unhealthy dietary pattern independently predicted increased depressive symptoms across time, before and after adjustment for potential confounders and baseline depressive symptoms, but only for those in the oldest cohort. Dietary patterns did not explain the relationship between socioeconomic position and depressive symptoms.


CONCLUSIONS
The results of this study confirm that the relationship between habitual dietary intake and depressive symptoms is somewhat explained by socioeconomic circumstances and other health behaviours, but suggest that long term exposure to unhealthy dietary habits independently predisposes to depression over the lifecourse.
Division of Nutritional Psychiatry Research, IMPACT Strategic Research Centre, Deakin University, Geelong, Australia ; Department of Psychiatry, The University of Melbourne, Melbourne, Australia.
Felice N
FN
Jacka
Centre for Research on Ageing, Health and Well-being, The Australian National University, Canberra, Australia.
Nicolas
N
Cherbuin
Centre for Research on Ageing, Health and Well-being, The Australian National University, Canberra, Australia.
Kaarin J
KJ
Anstey
Centre for Research on Ageing, Health and Well-being, The Australian National University, Canberra, Australia.
Peter
P
Butterworth
D000328:Adult; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology* / Q000523:psychology; D003430:Cross-Sectional Studies; D003863:Depression / Q000453:epidemiology / Q000209:etiology*; D004032:Diet / Q000009:adverse effects; D005247:Feeding Behavior; D005260:Female; D015438:Health Behavior; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D012923:Social Class; D055815:Young Adult