Dental fluorosis and self-reported depression among young adults in the United States

Introduction Chronic low-level fluoride exposure has been associated with depressive symptoms in animals and child internalizing behaviors in the United States (US); however, this study is the first to examine whether excess early life fluoride exposure is associated with depressive symptoms in US adults. Methods Participants were 886 adults aged 18–29 years from the National Health and Nutrition Examination Survey (NHANES) 2015–2016. Dental fluorosis, a marker of excess fluoride exposure during tooth development, was assessed using the Dean's Fluorosis Index (DFI). Self-reported depression was measured using the Patient Health Questionnaire (PHQ-9). We classified participants as having depression if they scored ≥10 and satisfied certain clinical criteria. We also classified depression symptom severity. Survey-weighted and covariate-adjusted binomial and multinomial logistic regression examined associations of dental fluorosis with presence and severity of depression, respectively. Results Participants were 24 years-old on average. Approximately 70% of participants had dental fluorosis that was mostly very mild or mild and 5% reported depression. Participants with dental fluorosis had 1.8 times the odds of reporting current depression compared to those without fluorosis (OR = 1.78; 95% CI: 1.03–3.07; p = 0.04). This association was significant for very mild/mild fluorosis and depression (OR = 1.82, 95% CI: 1.06–3.11, p = 0.031) but not moderate/severe fluorosis and depression ( p = 0.814). Dental fluorosis was not associated with depressive symptom severity. Discussion Having very mild or mild dental fluorosis was associated with higher odds of young adults in the US reporting depressive symptoms; however, prospective studies are needed to further examine this association.