Background and Objective:
The extensive use and bioaccumulation of per- and polyfluoroalkyl (PFAS)-containing substances over time raise concerns about their health impacts, which include mental issues such as depression. However, there is a lack of studies about this relationship, especially in middle-aged and older adults. Thus, the present study aims to evaluate the association between PFAS and depression. In addition, considering the importance of PFAS in the promotion of adipogenesis, and the fact of obesity and depression share about 12% to 20% of pleiotropic genes, the analyses will also be stratified by the body fat status.

Methods:
A cross-sectional study with 479 subjects (56.4% women, 25-89 years) was conducted. Four PFAS were measured in serum: perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluorooctane sulfonate (PFOS). The depression was assessed by the Patient Health Questionnaire (PHQ-9) or the Center for Epidemiologic Studies Depression scale (CES-D). The body fat percentage was predicted on a scale with multi-frequency bioelectrical impedance analysis.

Results:
The prevalence of high body fat and depression were respectively, 41.1% and 7.9%. The fully adjusted model included the co-variables: age, sex, educational level, income, smoking, physical activity, and the questionnaire to assess depression. Only PFOA was significantly associated in the whole sample (Prevalence Rate - PR:1.95 Confidence Interval-CI 95%:1.04-3.65). However, in the group with normal adiposity, PFOA (3.11, CI95%:1.53-6.34), PFNA (2.54, CI 95%:1.32-4.90), and PFDA (2.10, CI95%:1.09-4.01) were also significant.

Conclusion:
After stratifying the sample, associations with depression became more apparent in three of the four PFAS in the group with normal adiposity. Future research should investigate the role of obesity, as well as the biological plausibility and possible mechanisms increasing the limited number of evidence on the effect of PFAS on public mental health.