Vitamin D and depressive symptoms in an early adolescent cohort.

BACKGROUND: To explore the cross-sectional and longitudinal association between vitamin D and depressive symptoms across early adolescence. METHODS: This longitudinal study included 1607 early adolescents [mean (s.d.) age, 12.49 years; 972 (60.5%) males] from the Chinese Early Adolescents Cohort, recruited from a middle school in Anhui Province and followed up annually (2019-2021). Serum 25(OH)D levels were measured in both 2019 and 2021. Self-reports on depression were assessed at each of three time points from 2019 to 2021. RESULTS: In the whole sample, higher baseline serum 25(OH)D levels were linked with a lower risk of cumulative incident depression within two-year follow-ups (adjusted RR = 0.97, 95% CI 0.94-0.99) and the increasing trajectory of depression symptoms across the three waves (adjusted RR = 0.97, 95% CI 0.95-0.99). Baseline vitamin D deficiency (VDD) (adjusted RR = 1.50, 95% CI 1.10-2.05) were associated with an increased risk for the increasing trajectory of depression symptoms across the three waves. Remitted VDD was positively related to one dichotomous depression symptoms across three waves (adjusted OR 2.15, 95% CI 1.15-4.01). The above-mentioned significant association was also found in males. Additionally, baseline VDD (adjusted OR 1.59, 95% CI 1.04-2.44) and persistent VDD (adjusted OR 1.58, 95% CI 1.02-2.60) were linked to an increased risk of having two dichotomous depression symptoms only in males. CONCLUSIONS: Our results highlight a prospective association between baseline vitamin D and depression risk in early adolescents. Additionally, a male-specific association between vitamin D and depression risk was observed. Our findings support a potential beneficial effect of vitamin D supplementation in reducing depression risk in early adolescents.