Background: Depression has been reported to be more common in inflammatory bowel disease (IBD) than in the reference population. Since vitamin D deficiency has been associated with depression in other inflammatory diseases, the aim of the present study was to investigate possible associations between depressive symptoms and vitamin D deficiency in IBD.
Methods: Participants were recruited from nine hospitals in the southeastern and western regions of Norway to participate in a multicentre study from March 2013 to April 2014. Clinical and epidemiological data were collected by interview, from laboratory tests and medical records. Depression was measured with the Hospital Anxiety and Depression Scale (HADS). Depression was defined as HADS-D subscore >8 and severe depression as subscore >11. Disease activity was assessed with clinical indices (Harvey Bradshaw index and simple clinical colitis activity index), C-reactive protein and faecal calprotectin. Vitamin D deficiency was defined as a 25-OH-D <50 nmol/l. The possible association between depression and vitamin D deficiency was investigated using Pearson correlation coefficient for continuous variables and with Students T-tests for categorical variables.
Results: In total, 407 patients were available for analyses, 229 (56%) with Crohn's disease (CD) and 178 (44%) with Ulcerative colitis (UC). There were no significant differences between UC and CD patients regarding age or gender, but CD patients had significantly longer disease duration (median 11 vs. 6 years since diagnosis). Almost 50% (199/407) of the patients had vitamin D deficiency. Depression was found in 14% (57/407) and severe depression in 17% (17/407) with even distribution between men and women and between CD and UC. In general, no significant correlation between the HADS-D and vitamin D levels were observed. In addition, no significant differences in mean vitamin D levels among patients over or under cut-off for depression (HADS-D >8, p=0.10; HADS-D >11, p=0.26) were found.
Conclusions: In the current study, no significant associations between Vitamin D deficiency and depression were observed in IBD patients.