Patterns of dietary intake and psychological distress in older Australians: benefits not just from a Mediterranean diet

Background: Anxiety and depression contribute to morbidity in elderly adults and may be associated with diet. We investigated the association between diet and psychological distress as a marker for depression. Methods: Dietary patterns were defined by factor analysis or the Mediterranean Diet Score (MDS); depression and anxiety were assessed 12 years later. A total of 8,660 generally healthy men and women born in Australia and aged 50-69 years from the Melbourne Collaborative Cohort Study were included. At baseline (1990-1994), diet (food frequency questionnaire), education, Socio-Economic Indexes for Areas (SEIFA) Index of Relative Socio-economic Disadvantage, medication use, social engagement, physical activity, smoking status, alcohol use, and health conditions were assessed; at follow-up (2003-2007), psychological distress was assessed using the Kessler Psychological Distress Scale (K10). Logistic regression was used to identify associations between diet and a K10 score >= 20, indicative of psychological distress. Results: The MDS was inversely associated with psychological distress, with the odds ratio in the top-scoring group relative to the lowest scoring group being 0.72 (95% confidence interval = 0.54-0.95). Stronger adherence to a traditional Australian-style eating pattern was also associated with a lower K10 score at follow-up, with the odds ratio for having a K10 score indicative of psychological distress for the top 20% of adherence to this pattern relative to the lowest being 0.61 (95% confidence interval = 0.40-0.91). Conclusions: A Mediterranean-style diet was associated with less psychological distress, possibly through provision of a healthy nutrient profile. The Australian dietary pattern, which included some foods high in fat and sugar content along with whole foods, also showed a weak inverse association. Adherence to this pattern may reflect a feeling of belonging to the community associated with less psychological distress.