Association of formaldehyde concentration with depression risk in US adults: a population-based epidemiology study

The association of formaldehyde exposure with depression remains unknown. We used the data from National Health and Nutrition Examination Survey (NHANES) 2015-2016 to evaluate the association between formaldehyde exposure and depression. Multivariable logistic regressions and restricted cubic spline (RCS) were implemented to examine the association between formaldehyde exposure and depression. A total of 1336 participants were included in the analysis, of which 110 (8.23%) participants were depressed. After adjusting for confounders, a significant association between formaldehyde exposure and depression (OR = 1.01, 95% CI: 1.00-1.02, P = 0.043) was observed. The RCS plot showed a positive association in a linear manner (P_Nonlinear = 0.109), and the risk began to rise rapidly with concentrations above 129.37 nmol/g HB. The positive association remained in participants with high-intensity physical activity (OR = 1.08, 95% CI: 1.02-1.13, P = 0.003), but not in participants with other physical activities. Moreover, we constructed a novel nomogram to easily estimate the individual-specific probabilities of depression. In conclusion, formaldehyde exposure was associated with an elevated risk of depression, and the effect exhibited differences in participants with different levels of physical activity.