Objective: Vitamin D deficiency is common among immigrants, who, as a group, have heightened risk of psychosis. This study aimed to determine vitamin D levels among immigrants and Norwegians with psychosis compared to the general population and their association to clinical characteristics.
Method: This study compared vitamin D levels between immigrants and Norwegians within and between samples of patients with psychosis from a catchment area-based cross-sectional study (2002-2007) with a sample from a population-based health study from the same catchment area (2000-2001). The psychosis sample included patients with a Structured Clinical Interview for DSM-IV Axis I Disorders diagnosis of psychotic disorder (67 immigrants, 66 Norwegians). The reference sample consisted of 1,046 subjects (177 immigrants, 869 Norwegians). Serum levels of vitamin D were measured by radioimmunoassay, and results were presented as 25-hydroxyvitamin D levels.
Results: Over 80% (n = 55) of immigrant patients with psychosis had insufficient/deficient serum levels of 25-hydroxyvitamin D (< 50 nmol/L). Immigrants had higher rates of 25-hydroxyvitamin D deficiency than Norwegians (P < .001). Norwegians with psychosis had lower serum levels of 25-hydroxyvitamin D than Norwegians in the reference sample from the general public (P < .001). 25-hydroxyvitamin D levels correlated with certain negative/depressive symptoms among patients with psychosis.
Conclusions: An alarmingly high percentage of immigrants and Norwegians with psychotic disorders have 25-hydroxyvitamin D deficiency. This has important clinical implications as it suggests possible beneficial effects of vitamin D medication/heliotherapy within this group.
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