Cadmium, Lead, and Depressive Symptoms: Analysis of National Health and Nutrition Examination Survey 2011-2012

Background: Several studies have noted an association between tobacco smoke and depression. Cadmium and lead are neurotoxicant components of tobacco smoke. The objective of the present study is to investigate the potential association between blood cadmium (BCd) and blood lead (BPb) with current depressive symptoms in the US adult population.

Methods: We conducted cross-sectional analyses of adult participants (≥ 20 years) from the National Health and Nutrition Examination Survey 2011-2012 (N = 3,905). Multivariate logistic regressions were used to analyze the association between BCd and BPb with depressive symptoms; analyses were also stratified on sex and age groups (20-47 years and ≥ 48 years). Presence or absence of depressive symptoms was determined using the Patient Health Questionnaire module.

Results: Individuals in the highest quartile of BCd had higher odds of having depressive symptoms (odds ratio = 1.68; 95% confidence limits: 1.12, 2.51). This association was found only in male participants and, more specifically, in younger adult male participants (20-47 years). We found that BPb, cigarette smoking, and obesity were associated with depressive symptoms in younger female adults.

Conclusions: In this study, we report associations between BCd and BPb with current depressive symptoms that were modified by age and sex. Reverse causation cannot be ruled out as a possible explanation since depression may lead to behavioral changes that increase exposure to cadmium and lead (ie, tobacco smoke). The continued efforts at reducing cadmium through tobacco smoking cessation programs may decrease the prevalence of current depressive symptoms.