Inflammatory dietary patterns and depressive symptoms in Italian older adults

Older adults are more susceptible to higher inflammatory levels and depression. Moreover, diet may influence inflammation as well as depression but no previous study examined whether inflammatory dietary patterns are related to depression in an older population. To investigate the longitudinal association between inflammatory dietary patterns (using reduced rank regression (RRR)) and depressive symptoms in a population sample of Italian older adults.

We included 827 participants (aged≥65years) at baseline in 1998. Follow-up measurements were collected after 3, 6 and 9years. We used RRR to identify inflammatory dietary patterns at baseline. The Centre for Epidemiologic Studies Depression (CES-D) scale was used to assess depressive symptoms by using continuous scores and depression by using a cut-off point (CES-D≥20).

We identified two inflammatory dietary patterns using different sets of response variables. Dietary pattern I was related to inflammatory markers C-reactive protein (CRP), interleukin (IL)-6, tumor necrosis factor α and was characterized by high intakes of refined grains, sweet snacks, pasta and rice. After full adjustment for confounders, no longitudinal association was found when comparing extreme quartiles of this dietary pattern and depressive symptoms (Q1vs Q4, model 4: B=0.04, 95% CI: -0.06, 0.13) or depression (Q1vs Q4, model 4: OR=0.90, 95% CI: 0.55, 1.45). Dietary pattern II was related to inflammatory markers CRP, IL-18, IL-1β, IL-1 receptor antagonist and was characterized by high intakes of pasta, sugar-sweetened beverages, processed meat and chocolate and sweets. When comparing extreme quartiles, this dietary pattern was not longitudinally associated with depressive symptoms (Q1vs Q4, model 4: B=-0.04, 95% CI: -0.13, 0.05) but an inverse association was found for depression (Q1vs Q4, model 4: OR=0.56, 95% CI: 0.40, 0.94).

Our study does not support the hypothesis that dietary patterns linked to inflammatory markers are associated with higher depressive symptoms and higher depression incidence. However, dietary intake in our population of older adults was quite homogeneous which makes it difficult to show clear associations.