Relationship of low vitamin D status with positive, negative and cognitive symptom domains in people with first-episode schizophrenia.

ABSTRACT

AIM: Deficient vitamin D levels are very common among Americans of all ages and ethnicities, but little is known about its prevalence or associated problems among those with schizophrenia. METHODS: Stored plasma from 20 recent onset schizophrenia subjects and 20 matched healthy comparison subjects were analysed for 25 OH vitamin D, and related to measures of symptom severity and neurocognition. RESULTS: There was no significant difference in mean 25 OH vitamin D between the schizophrenia and the healthy comparison subjects (28.2 standard deviation (SD) 12.6 ng mL(-1) vs. 29.9 SD 14.3 ng mL(-1) ), and about half the subjects in each group had insufficient levels (<30 ng mL(-1) ). Among psychosis subjects, greater severity of negative symptoms was correlated with lower vitamin D status (r = -0.55, P = 0.012); the correlations of overall symptom severity and positive symptom severity with 25 OH vitamin D levels approached significance (r = -0.42, P = 0.07 and r = -0.36, P = 0.12, respectively). There was no relationship of vitamin D with depressive symptoms. Among the schizophrenia subjects, lower 25 OH vitamin D levels were associated with more severe overall cognitive deficits (r = 0.56, P = 0.019). CONCLUSION: This study found that lower vitamin D levels in schizophrenia subjects were associated with more severe negative symptoms and overall cognitive deficits. However, the cross-sectional design precludes any conclusions about whether low vitamin D status in fact causes more severe negative symptoms and cognitive impairments. No relationship was found between lower vitamin D levels and depressive symptoms.