Purpose To assess the relationships of sun exposure history, supplementation and environmental factors to vitamin D levels in multiple sclerosis (MS) patients and to evaluate the associations between sun exposure and MRI measures. Methods This study included 264 MS patients (mean age 46.9±10 years, disease duration 14.6±10 years; 67.8% relapsing-remitting, 28% secondary progressive and 4.2% primary progressive MS) and 69 healthy controls. Subjects underwent neurological and 3 T MRI examinations, provided blood samples and answered questions to a structured questionnaire. Information on race, skin and eye colour, supplement use, body mass index (BMI) and sun exposure was obtained by questionnaire. The vitamin D metabolites (25-hydroxy vitamin D3, 1, 25-dihydroxy vitamin D3 and 24, 25- dihydroxy vitamin D3) were measured using mass spectrometry. Results Multivitamin supplementation ( partial correlation rp=0.29, pp=-0.24, p=0.001), summer sun exposure (r p=0.22, p=0.002) and darker eye colour (rp=-0.18, p=0.015) had the strongest associations with vitamin D metabolite levels in the MS group. Increased summer sun exposure was associated with increased grey matter volume (GMV, rp=0.16, p=0.019) and whole brain volume (WBV, r p=0.20, p=0.004) after correcting for Extended Disability Status Scale in the MS group. Inclusion of 25-hydroxy vitamin D3 levels did not substantially affect the positive associations of sun exposure with WBV (r p=0.18, p=0.003) and GMV (rp=0.14, p=0.026) in the MS group. Conclusions Sun exposure may have direct effects on MRI measures of neurodegeneration in MS, independently of vitamin D.
ASJC Scopus subject areas
- Clinical Neurology
- Psychiatry and Mental health
- Arts and Humanities (miscellaneous)