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J Neurol Neurosurg Psychiatry doi:10.1136/jnnp-2012-304661
  • Multiple sclerosis
  • Research paper

Interdependence and contributions of sun exposure and vitamin D to MRI measures in multiple sclerosis

  1. Murali Ramanathan2,3
  1. 1Department of Neurology, Buffalo Neuroimaging Analysis Center, State University of New York, Buffalo, New York, USA
  2. 2Department of Pharmaceutical Sciences, State University of New York, Buffalo, New York, USA
  3. 3Department of Neurology, Multiple Sclerosis Center, State University of New York, Buffalo, New York, USA
  1. Correspondence to Professor M Ramanathan, Department of Pharmaceutical Sciences, State University of New York, Buffalo, 355 Kapoor Hall, Buffalo, NY 14214-8033, USA; Murali{at}Buffalo.Edu
  • Received 24 November 2012
  • Revised 3 January 2013
  • Accepted 10 January 2013
  • Published Online First 5 February 2013

Abstract

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, p<0.001), BMI (rp=−0.24, p=0.001), summer sun exposure (rp=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, rp=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 (rp=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.