Low vitamin D is associated with negative and depressive symptoms in psychotic disorders

Background: There are indications that low S-25(OH)D is associated with increased disease severity in psychotic disorder. Our first aim was to investigate the relations between low S-25(OH)D and positive, negative and depressive symptoms. Our second aim was to explore if associations between S-25(OH)D and symptoms were influenced by levels of inflammatory markers. Methods: Participants (N=358) with a medical history of one or more psychotic episodes were recruited. Current symptomatology was assessed by The Structured Interview for the Positive and Negative Syndrome Scaleanalyzed by a five-factor model. The Calgary Depression Scale for Schizophrenia was used to assess depression and suicidal ideation. Blood samples were analyzed for S-25(OH)D, CRP, sTNF-R1, IL-Ra and OPG. We performed bivariate correlations and multiple regression models to evaluate the effect of S-25(OH)D on the outcomes. Results: Low S-25(OH) D was significantly associated with negative symptoms (adjusted R-2 = 0.113, F(6,357) = 8.58, p < 0.001) and with depression (adjusted R2=0.045, F(4,357) = 5.233, p < 0.001) when adjusting for possible confounding factors (i.e. gender, education, diagnose, hospitalization status, ethnicity, season and thyroid status). CRP was correlated with both S-25(OH)D (rho=-0.13, p=0.02) and negative symptoms (rho=0.14, p=0.01), but did not act as amediator. The correlations between S-25(OH)D and the inflammatory markers sTNF-R1, IL-Ra and OPG were not significant. Conclusion: There is a strong association between lowS-25(OH)D and higher negative and depressive symptoms in psychotic disorders. Randomized controlled trials should be performed to investigate the effect of vitamin D supplementation as adjuvant treatment strategy in patients with prominent negative or depressive symptoms. (C) 2016 Elsevier B.V. All rights reserved.