On the geoepidemiology of Multiple Sclerosis and environmental and infectious determinants of its clinical course
Simpson Jr,, S (2011) On the geoepidemiology of Multiple Sclerosis and environmental and infectious determinants of its clinical course. PhD thesis, University of Tasmania.
Multiple sclerosis (MS) is a chronic, demyelinating condition of the central nervous system, manifesting
in alteration or loss of motor, sensory and cognitive function. The causes of MS are unclear but include
genetic and environmental factors. This thesis presents several epidemiologic analyses, examining MS
geoepidemiology, locally and globally, as well as evaluating key environmental and infectious
determinants of clinical course.
The first analysis chapter examines MS epidemiology in the Greater Hobart region of Tasmania over the
interval 1951 to 2009. This analysis found a significant increase in prevalence, this mediated by a
significantly decreased mortality and increased longevity, as well as evidence of an increasing
female/male sex ratio.
Next is a meta-analysis of MS prevalence and its association with latitude. This work, utilising the
largest collection of MS prevalence studies, found a significant positive association between MS
prevalence and latitude. This provides evidence in favour of the latitudinal gradient hypothesis and for
environmental factors underlying the gradient, most particularly personal ultraviolet radiation (UVR)
exposure and vitamin D.
The association between serum 25-hydroxyvitamin D (25(OH)D) and relapse was examined in a
prospective cohort with clinically-definite MS followed for 2.3 years. This analysis found a significant
inverse association between higher levels of 25(OH)D and subsequent hazard of relapse. This study
provides key evidence that is needed to justify conducting randomised clinical trials of vitamin D
supplementation in reducing relapse frequency in MS.
In this MS cohort, it was also found that persons on interferon-β (IFN-β) therapy had significantly
higher 25(OH)D levels and that the association between personal sun exposure and 25(OH)D was
stronger compared to those not on IFN-β. Importantly, the above association between 25(OH)D and
relapse was only observed for those on IFN-β therapy.
|Item Type:||Thesis (PhD)|
|Additional Information:||Copyright the Author|
|Keywords:||multiple sclerosis, epidemiology, vitamin D, human herpesvirus|
|Deposited By:||ePrints Officer|
|Deposited On:||14 Dec 2011 10:42|
|Last Modified:||24 Aug 2012 11:55|
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