Gender differences in the relationship between nicotine exposure and symptoms of depression.

Background: Tobacco-derived nicotine exposure is linked to depression. However, the associations of nicotine and its metabolites with symptoms of depression, particularly concerning gender differences, remain underexplored.

Methods: The characteristics and total nicotine equivalents (TNE) of 1001 subjects were determined. The association between the TNE and symptoms of depression, accounting for gender differences, was investigated using generalized linear models and subgroup analyses.

Results: Men exhibited significantly greater levels of the nicotine exposure indicators TNE2, TNE3, TNE6, and TNE7 (P < 0.005). A significantly greater percentage of women (23.45 %) than men (9.81 %) exhibited symptoms of depression (P < 0.0001). In women, the relationship between the TNE and depression was reflected by a U-shaped curve with significant inflection points, particularly for TNE3, TNE6, and TNE7. Furthermore, in women, concentrations above 48.98 nmol/mL for TNE3, 53.70 nmol/mL for TNE6, and 57.54 nmol/mL for TNE7 were associated with 154 %, 145 %, and 138 % increases in the risk of depression, respectively. In contrast, these associations did not reach significance among men.

Limitations: The cross-sectional design limits the ability to infer causality between nicotine exposure and depressive symptoms. Larger-scale studies are needed to confirm these findings.

Conclusions: Gender could be a significant factor influencing the relationship between nicotine exposure levels and symptoms of depression. The impact of nicotine exposure on symptoms of depression should be particularly considered among women.

Implications: This study revealed the complex relationship between tobacco-related nicotine exposure and depressive symptoms, with a particular focus on gender differences. Our results revealed a distinct U-shaped correlation between total nicotine equivalents and depression in women, which differed from that in men. These findings emphasize the importance of tailoring clinical approaches to address nicotine exposure and manage depressive symptoms based on gender.