Objective: Non-clinical psychotic experiences are common and distressing. It has been hypothesized that early life vitamin D deficiency may be a risk factor for psychosis-related outcomes, but it is not known if circulating concentrations of 25-hydroxyvitamin D (25(OH)D) during childhood are associated with psychosis-related outcomes or whether the two different forms of 25(OH)D, (25(OH)D(3) and 25(OH)D(2), have similar associations with psychosis-related outcomes.
Methods: We investigated the association between serum 25(OH)D(3) and 25(OH)D(2) concentrations and psychotic experiences in a prospective birth cohort study. Serum 25(OH)D(3) and 25(OH)D(2) concentrations were measured at mean age 9.8 years and psychotic experiences assessed at mean age 12.8 years by a psychologist (N = 3182).
Results: Higher 25(OH)D(3) concentrations were associated with lower risk of definite psychotic experiences (adjusted odds ratio: OR (95% confidence interval: CI) 0.85 (0.75-0.95)). Higher concentrations of 25(OH)D(2) were associated with higher risk of suspected and definite psychotic experiences (adjusted odds ratio: OR (95% confidence interval: CI) 1.26 (1.11, 1.43)). Higher 25(OD)D(2) concentrations were also weakly associated with definite psychotic experiences (adjusted OR (95% CI) 1.17 (0.96, 1.43), though with wide confidence intervals including the null value.
Conclusions: Our findings of an inverse association of 25(OH)D(3) with definite psychotic experiences is consistent with the hypothesis that vitamin D may protect against psychosis-related outcomes.