Mediterranean Diet Negatively Associated with Depression in Older Adults

by | Mar 1, 2023 | 2023, Aging, Brain Health, Depression, Mediterranean Diet

Written by Taylor Woosley, Staff Writer. Results for Cox models (participants without depression at baseline and adjusting for age, sex, and years of education) show that with each unit increase in the MedDietScore, indicating greater MeDi adherence, was associated with a 6.2% decrease in the risk for depression (p = 0.001).

aging coupleOver 300 million people are affected by major depressive disorder (MDD), making it the leading cause of disability world-wide1. MDD pathophysiology has been strongly associated with the dysregulation of serotonin, oxidative stress, suboptimal mitochondrial function, and immune inflammation2. Depression is frequent in the elderly population, with research finding prevalence rates of depressive symptomatology to be 17.1% in individuals 75 years old and older and 19.5% in individuals 50 years and older3.

The Mediterranean diet (MeDi) is one of the classical anti-inflammatory dietary patterns and has been perceived to have benefits on multiple aspects of human health, including mental and brain health4. The diet is abundant in plant foods such as fruits and vegetables, admitting animal-derived food in small quantities, with olive oil being consumed as the main dietary lipid5. All of these dietary components are rich in polyphenols which exerts protective effects on mental health via upregulating the body’s natural defense systems, stabilizing free radicals, and reducing oxidative damage6.

Mamalaki et al. conducted a study to examine the relationship between adherence to the MeDi and specific food groups, with depression incidence in a representative cohort of older adults, while considering the participants’ cognitive status. Data of participants aged ≥65 years old was collected from the Hellenic Longitudinal Investigation of Aging and Diet (HELIAD), a population-based, multidisciplinary, collaborative study conducted in central Greece. Subjects took part in appointments including a neurological examination and neuropsychological assessment, utilizing structured questionnaires, psychometric tests, and clinical evaluations.

The current analysis included 879 participants who had a follow-up evaluation, had full data on the assessment regarding depression, and did not have depression at baseline. Habitual dietary intake was analyzed at baseline using a semi-quantitative Food Frequency Questionnaire, with responses being converted to daily intakes of specific food items as portions. Adherence to the MeDi pattern was assessed and resulted in the MedDietScore, a composite score based on weekly consumption of 11 food groups. Physical activity was assessed using the Athens Physical Activity Questionnaire (APAQ). The Geriatric Depression Scale was used to assess depressive symptoms. At baseline and the follow-up evaluation, participants underwent comprehensive neuropsychological tests, and the z-scores were calculated from each neuropsychological test variable, based only on participants without a mild cognitive impairment (MCI) or dementia diagnosis.

Cox proportional hazards models with depression incidence were calculated as the dichotomous outcome, and adherence to the MeDi as the independent variable. The time-to-event variable was the number of years from the baseline evaluation to the visit where depression was determined. In all models, MedDietScore was entered into the models both as a continuous and a categorical variable, as tertiles. Continuous variables included age, years of education, baseline Global Cognition Score and the follow-up interval duration, while sex was treated as a categorical variable.

The current analysis consisted of 879 participants, with a mean follow-up interval of 3.0 ± 0.8 years. At follow-up, 170 individuals developed depression (19.3% of participants). Significant findings of the study are as follows:

  • Results from Cox models show that each unit increase in the MedDietScore, indicating greater MeDi adherence, was associated with a 6.2% decrease in the risk for depression (p = 0.001).
  • When MeDi adherence was entered into the models as tertiles, those in the highest tertiles (highest MeDi adherence) had a 46% lower risk for depression for every unit increase in the MedDietScore, compared with those having the lowest MeDi adherence (p = 0.006), with a significant trend for dose-response.
  • The consumption of fruits and alcoholic drinks was negatively associated with depression incidence; for every portion increase in fruits and alcoholic drinks, the risk for depression decreased by 15.2% and 31.3%, respectively (p < 0.05 for both).

Results of the study show that adherence to the MeDi was negatively associated with depression incidence. Further studies are necessary to better comprehend the beneficial effects of the MeDi diet on mood disorders. Study limitations include the relatively short follow-up interval, the potential for recall bias based on the self-reporting nature of diet and depression assessment, and the lack of depression diagnosis being set by psychiatrists.

Source: Mamalaki, Eirini, Eva Ntanasi, Alexandros Hatzimanolis, Maria Basta, Mary H. Kosmidis, Efthimios Dardiotis, Giorgos M. Hadjigeorgiou, Paraskevi Sakka, Nikolaos Scarmeas, and Mary Yannakoulia. “The Association of Adherence to the Mediterranean Diet with Depression in Older Adults Longitudinally Taking into Account Cognitive Status: Results from the HELIAD Study.” Nutrients 15, no. 2 (2023): 359.

© 2023 by the authors. Licensee MDPI, Basel, Switzerland.This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

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Posted March 1, 2023.

Taylor Woosley studied biology at Purdue University before becoming a 2016 graduate of Columbia College Chicago with a major in Writing. She currently resides in Glen Ellyn, IL.

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