Vitamin D levels among adult psychiatric inpatients and the association with psychosis.

Background: The association between low vitamin D levels and mental illness has been described in earlier research. The aim of our study was to examine the association between vitamin D levels with psychotic symptoms among hospitalized patients.

Methods: A total of 1,456 patient records from an academic psychiatric hospital were examined. Vitamin D levels were classified as normal (>30 ng/mL); insufficient (20 to 30 ng/mL); and deficient (<20 ng/mL). We then analyzed the association among vitamin D groups and symptoms of psychosis.

Results: The average vitamin D level in our sample was 23.59 ng/mL, with 76.2% of patients presenting with vitamin D levels <30 ng/mL. There was a significant association between vitamin D levels <20 ng/mL and symptoms of psychosis (P < .05). African American patients had lower mean vitamin D levels than White patients (15.6 ± 0.2 ng/mL vs 25.8 ± 0.4 ng/mL, P < .001). There was no sex difference in vitamin D levels (females: 23.3 ± 11.5 ng/mL; males: 23.9 ± 11.0 ng/mL).

Conclusions: Patients with vitamin D levels <30 ng/mL were 1.5 times more likely to have symptoms of psychosis. Patients who were African American, Hispanic, Asian, or biracial had lower vitamin D levels than patients who were White. Multivariate analysis found that after adjusting for age, sex, and race, the association between vitamin D and psychosis was not statistically significant. Possible explanations could include the known tendency to overdiagnose psychosis among individuals who are African American, referral bias, subgroup effect, or an epiphenomenon.