Relationship between exposure to multiple heavy metals and depressive symptoms in the US: The impact of alcohol consumption.

BACKGROUND/AIM: Although some heavy metals and alcohol consumption are known to have adverse effects on neurobehavioral symptoms, studies on the relationship between exposure to multiple metals and interaction between these factors are limited. In this study, we aimed to explore how multiple exposure to heavy metals with drinking habit in affecting depression using the National Health and Nutrition Examination Survey (NHANES) data.

METHODS

Data from the U.S. NHANES between 2007 and 2014 were used to examine the cross-sectional relationships between heavy metal exposure and depression in adult over 20 years. After applying the exclusion criteria, 6021 subjects were included in the final analysis. We used four urinary metals, including mercury (Hg), cadmium (Cd), lead (Pb), and arsenic (As), as exposure variables. The Patient Health Questionnaire (PHQ-9) was used to assess the depression symptoms of the participants. Multivariate linear regression (MLR) and quantile g-computation models were applied to investigate the effects of individual and multiple heavy metal exposures on depression, respectively. We also performed stratified analysis according to the alcohol habit of the participants.

RESULTS

The MLR models revealed that urinary Cd was positively associated with a continuous depression score (  = 0.39, 95 % confidence interval (CI): 0.24-0.53). Meanwhile, other urinary metals showed an insignificant positive relationship with depression. In quantile g-computation model, statistically significant positive relationship was observed between urinary heavy metal mixture and depression score (difference in PHQ-9 score increase = 0.32, 95 % CI: 0.14-0.50). When the model was stratified by drinking habit, a stronger relationship was observed in the heavy drinker group.

CONCLUSIONS

Comparing the results from different models, both individual urinary Cd and all the heavy metal mixtures were positively associated with depression. This association was stronger among those with heavy drinking habits. Future cohort studies are needed to confirm these associations and to clarify the causal relationship.