Plan D- Vitamin D Supplementation in Psychotic Disorders

Background: Impairment in cognitive processing speed is a consistent finding in schizophrenia spectrum disorder. Vitamin D deficiency is found to be significantly associated with reduced processing speed. In this study, we will investigate the effect from vitamin D supplementation on processing speed. Objective: The primary objective is to investigate whether vitamin D supplementation is superior to placebo in improving processing speed. The secondary objectives are to investigate whether vitamin D supplementation is superior to placebo in improving negative symptoms, social and physical activity. Study design: Randomized placebo-controlled double blind trial. Study population: Men and women, aged 18-65 years, diagnosed with a schizophrenia spectrum disorder, in treatment for their disorder at the Division for Mental Health at Akershus university hospital. Intervention: Participants will be randomized 1:1 to either vitamin D3 (50µg capsules) or placebo daily for 12 weeks. The medical product or placebo will be given in addition to treatment as usual. Study measures: Cognitive tests, symptom assessments and blood sampling for vitamin D analyses will be performed at baseline and after 12 weeks intervention. During the 12 week intervention period the participants will use a smart phone application (MinDag) for self-report and an actigraph (MotionWatch 8 actigraph from CamNtech) for registration of physical activity. Endpoints: Primary outcome is change in cognitive performance on the symbol coding test from the Brief assessment of Cognition in Schizophrenia (BACS). Secondary outcomes are change in performance on the the Category Fluency Test from the MATRICS Consensus Cognitive battery, change in negative symptoms from the clinician rated Brief negative symptom scale (BNSS), and change in self-reported negative symptoms from the scale Self-assessment of negative Negative Symptoms (SNS). Secondary outcomes also include change in self-reported social activities and