Associations between the mediterranean diet, traumatic brain injury and depressive symptoms

Background and Objectives Exposure to traumatic brain injury (TBI) increases risk for depressive symptoms. The Mediterranean diet has been associated with an improvement in depression severity and reduced inflammation. We sought to evaluate the potential moderating effect of the Mediterranean Diet between TBI with loss of consciousness (LOC) and depressive symptoms using the National Health and Nutrition Examination Survey (NHANES) dataset. Methods The dataset included a cross-sectional analysis of 2,583 participants with complete data. The main outcome was log-transformed depressive symptoms (Patient Health Questionnaire-9 [PHQ-9]) total score. Serum markers (serum albumin, total protein, and uric acid) and/or indices of systemic immunoinflammation (Neutrophil-to-Lymphocyte Ratio (NLR), Platelet-to-Lymphocyte Ratio (PLR), Monocyte-to-Lymphocyte Ratio (MLR), Systemic Immune-Inflammation Index (SII), etc.). Linear models to estimate PHQ-9 total scores using TBI history with LOC, high adherence to MD (vs. moderate/low adherence) and their interaction with covariates were built. Results TBI with LOC and low adherence to the Mediterranean Diet (β=0.31; p=0.001) and the interaction of TBI with LOC x high adherence to the mediterranean diet (β=-0.37; p=0.03) were associated with depressive symptoms. This interaction effect was present when including markers of systemic health as covariates. Discussion Adhering to the mediterranean diet was associated with lower depressive symptoms among participants with a history of TBI with LOC. Incorporating inflammatory measures into models did not remove this association. Classification of Evidence This study provides level III evidence that the mediterranean diet is associated with lower depressive symptoms in participants who self-reported TBI with LOC in a nationally representative sample.