Association of DASH and Depressive Symptoms with BMI over Adulthood in Racially and Socioeconomically Diverse Adults Examined in the HANDLS Study

A Narrative Review of the Association Between Healthy Dietary Patterns and Depression

The purpose of the present review is the investigation of healthy dietary patterns and diet quality in relation to depression risk. Nutritional psychiatry is to develop scientifically based research that defines the role of nutrition and nutrients in various aspects of mental health. Growing evidence from the field suggests that diet may play an important role in the prevention and/or treatment of depression. In contrast, there is evidence that unhealthy diets may increase the risk of depression. This emerging research suggests that dietary interventions could help prevent depression or be an alternative or adjunctive therapy for depression. The Mediterranean diet (MedDiet), the Dietary Approaches to Stop Hypertension (DASH) diet, and the vegetarian diet are examined in this review. The electronic databases PubMed, Scopus, and Google Scholar were searched for relevant studies published during the last five years. We found many results that support that healthy eating patterns (high in vegetables, fruits, whole grains, nuts, seeds, and fish, low in processed foods) are related to a reduction in the risk of depression. The most robust findings are related to MedDiet, where we also found several positive results for the DASH diet. Regarding the vegetarian diet, there are inconsistent reports. Furthermore, a consistent finding refers to a lower Dietary Inflammatory Index (DII) as associated with a lower depression risk. It has been observed that people suffering from depression have poorer nutritional quality, with lower fruit and vegetable intake. This observation may strengthen the argument that nutritional interventions should be incorporated as an important "pillar" in the multifactorial treatment of patients. However, more well-designed studies are needed to establish the relationship between dietary patterns and mental health. In particular, interventional, longitudinal studies could be more enlightening.

BMI and Allostatic Load Are Directly Associated with Longitudinal Increase in Plasma Neurofilament Light among Urban Middle-Aged Adults

BACKGROUND

Plasma neurofilament light chain (NfL) is a novel biomarker for age-related neurodegenerative disease. We tested whether NfL may be linked to cardiometabolic risk factors, including BMI, the allostatic load (AL) total score (ALtotal), and related AL continuous components (ALcomp). We also tested whether these relations may differ by sex or by race.

METHODS

We used data from the HANDLS (Healthy Aging in Neighborhoods of Diversity across the Life Span) study [n = 608, age at visit 1 (v1: 2004-2009): 30-66 y, 42% male, 58% African American] to investigate associations of initial cardiometabolic risk factors and time-dependent plasma NfL concentrations over 3 visits (2004-2017; mean ± SD follow-up time: 7.72 ± 1.28 y), with outcomes being NfLv1 and annualized change in NfL (δNfL). We used mixed-effects linear regression and structural equations modeling (SM).

RESULTS

BMI was associated with lower initial (γ01 = -0.014 ± 0.002, P < 0.001) but faster increase in plasma NfL over time (γ11 = +0.0012 ± 0.0003, P < 0.001), a pattern replicated for ALtotal. High-sensitivity C-reactive protein (hsCRP), serum total cholesterol, and resting heart rate at v1 were linked with faster plasma NfL increase over time, overall, while being uncorrelated with NfLv1 (e.g., hsCRP × Time, full model: γ11 = +0.004 ± 0.002, P = 0.015). In SM analyses, BMI's association with δNfL was significantly mediated through ALtotal among women [total effect (TE) = +0.0014 ± 0.00038, P < 0.001; indirect effect = +0.00042 ± 0.00019, P = 0.025; mediation proportion = 30%], with only a direct effect (DE) detected among African American adults (TE = +0.0011 ± 0.0004, P = 0.015; DE = +0.0010 ± 0.00048, P = 0.034). The positive associations between ALtotal/BMI and δNfL were mediated through increased glycated hemoglobin (HbA1c) concentrations, overall.

CONCLUSIONS

Cardiometabolic risk factors, particularly elevated HbA1c, should be screened and targeted for neurodegenerative disease, pending comparable longitudinal studies. Other studies examining the clinical utility of plasma NfL as a neurodegeneration marker should account for confounding effects of BMI and AL.