A Cross-Sectional Study of Vitamin D Deficiency Among Immigrants and Norwegians With Psychosis Compared to the General Population

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.

J Clin Psychiatry

Submitted: April 20, 2009; accepted July 14, 2009.

Online ahead of print: April 6, 2010 (doi:10.4088/JCP.09m05299yel).

Corresponding author: Akiah Ottesen Berg, Cand Psychol, Thematically Organized Psychosis study group, Institute of Psychiatry, University of Oslo, Oslo University Hospital, Building 49, Kirkeveien 166, N-0407 Oslo, Norway (a.o.berg@medisin.uio.no).