Association between different diet quality scores and depression risk: the REGICOR population-based cohort study

Background: Our aim was to determine the association between diet quality and depression incidence in the population-based REGICOR cohort study, Catalonia, Spain. Methods: Prospective observational study using participants’ baseline (2003–2006), follow-up (2007–2013) and clinical records data. Five diet quality scores were derived from a food frequency questionnaire (FFQ) at baseline: the relative Mediterranean Diet Score (rMED), the Modified Mediterranean Diet Score (ModMDS), a Dietary Approaches to Stop Hypertension (DASH) score, a Healthful Plant-based Diet Index (HPDI) and the World Health Organization Healthy Diet Indicator (WHO-HDI). Participants using pharmacological antidepressant treatment were excluded as a proxy for presence of depression at baseline. At follow-up, the Patient Health Questionnaire (PHQ-9) was applied to assess depressive symptoms (≥ 10 defining depressive disorder). A secondary outcome was depression diagnosis assessed through clinical records. Logistic regression and Cox proportional hazards models were used. Results: Main analysis included 3046 adults (50.3% women) with a mean age of 54.7 (SD = 11.6) years. After 6-years follow-up, 184 (6.04%) cases of depressive disorder were identified. There was 16% lower odds of depressive disorder per 1SD increase of rMED (OR = 0.84; 95%CI = 0.71–0.98). Secondary outcome analysis (n = 4789) identified 261 (5.45%) incident cases of clinical depression diagnosis over 12 years follow-up, and 19% lower risk of clinical depression was observed with the WHO-HDI (HR = 0.81; 95%CI = 0.70–0.93). Adjusting for BMI did not attenuate the findings. Conclusions: A significant inverse association between diet quality and depression incidence was found in this population-based cohort study, independent of sociodemographic, health and lifestyle. Adherence to a healthy diet could be a complementary intervention for the prevention of depression.