Abstract
BACKGROUND: Schizophrenia is a multifactorial disease involving interactions between genetic and environmental factors. Vitamin D has recently been linked to many metabolic diseases and schizophrenia. Vitamin D plays essential roles in the brain in the context of neuroplasticity, neurotransmitter biosynthesis, neuroprotection, and neurotransmission. Vitamin D receptors are demonstrated in most brain regions that are related to schizophrenia. However, very few studies in the literature examine the effects of 25-hydroxyvitamin D (25OHD) on schizophrenia symptoms. METHODS: This study aimed to examine the effects of vitamin D replacement on positive, negative, and cognitive symptoms of schizophrenia. Serum 25OHD levels of 52 schizophrenia patients were measured. SANS and SAPS were used to evaluate the severity of schizophrenia symptoms, and the Wisconsin Card Sorting Test: CV4 was used for cognitive assessment. The study was completed with 40 patients for various reasons. The patients whose serum 25OHD reached optimal levels after vitamin D replacement were reevaluated with the same scales in terms of symptom severity. The SPSS 25 package program was used for statistical analysis. The Independent-Samples t-test was used to examine the relationship between the variables that may affect vitamin D levels and the vitamin D level and to examine whether vitamin D levels had an initial effect on the scale scores. RESULTS: The mean plasma 25OHD levels of the patients was 17.87 ± 5.54. A statistically significant relationship was found only between the duration of sunlight exposure and 25 OHD level (p < 0.05). The mean SANS and SAPS scores of the participants after 25OHD replacement (23.60 ± 15.51 and 7.78 ± 8.84, respectively) were statistically significantly lower than mean SANS and SAPS scores before replacement (51.45 ± 17.96 and 18.58 ± 15.59, respectively) (p < 0.001 for all). Only the total attention score was significantly improved after replacement (p < 0.05). CONCLUSION: The data obtained from our study suggest that eliminating the 25OHD deficiency together with antipsychotic treatment can improve the total attention span and positive and negative symptoms in schizophrenia. The 25OHD levels should be regularly measured, replacement should be started when necessary, and the patients should be encouraged to get sunlight exposure to keep optimal 25OHD levels.