Higher levels of reported sun exposure, and not vitamin D status, are associated with less depressive symptoms and fatigue in multiple sclerosis

Objective: Insufficient sun exposure and vitamin D deficiency have both been associated with increased risk of multiple sclerosis (MS). Depressi on, anxiety, fatigue and cognitive impairment are prevalent and disabling symptoms in MS. Our objective was to examine the associations between personal sun exposure and serum 25-hydroxyvitamin D (25(OH)D), and depression, anxiety, fatigue and cognition.

Methods: A total of 198 participants with multiple sclerosis were followed prospectively for an average of 2.3 years. Assessments of serum 25(OH)D, sun exposure, depression, anxiety and fatigue were carried out biannually; cognition was assessed annually.

Results: Personal reported sun exposure was inversely associated with depression scores (β −0.26 (95%CI −0.40, −0.12);P ≤ 0.001) and fatigue scores (β −0.65 (95%CI −1.23, −0.07); P = 0.028). Only high levels of 25(OH)D (>80 nm) were inversely associated depression scores (β −0.64 (95%CI −1.15, −0.13); P = 0.015), but this was not significant after adjustment for reported sun exposure. No associations were seen between reported sun exposure or serum 25(OH)D levels and anxiety or cognition scores.

Conclusion: We found that higher levels reported sun exposure, rather than 25(OH)D levels, were associated with less depressive symptoms and levels of fatigue. The role of UV or light therapy will need to be evaluated in randomized controlled trials to confirm an effect on these symptoms in MS.