Orton, S. M. et al. Sex ratio of multiple sclerosis in Canada: a longitudinal study. Lancet Neurol. 5, 932-936

Wellcome Trust Centre for Human Genetics and Department of Clinical Neurology, University of Oxford, Oxford, UK.
The Lancet Neurology (Impact Factor: 21.9). 12/2006; 5(11):932-6. DOI: 10.1016/S1474-4422(06)70581-6
Source: PubMed


Incidence of multiple sclerosis is thought to be increasing, but this notion has been difficult to substantiate. In a longitudinal population-based dataset of patients with multiple sclerosis obtained over more than three decades, we did not show a difference in time to diagnosis by sex. We reasoned that if a sex-specific change in incidence was occurring, the female to male sex ratio would serve as a surrogate of incidence change.
Since environmental risk factors seem to act early in life, we calculated sex ratios by birth year in 27 074 Canadian patients with multiple sclerosis identified as part of a longitudinal population-based dataset.
The female to male sex ratio by year of birth has been increasing for at least 50 years and now exceeds 3.2:1 in Canada. Year of birth was a significant predictor for sex ratio (p<0.0001, chi(2)=124.4; rank correlation r=0.84).
The substantial increase in the female to male sex ratio in Canada seems to result from a disproportional increase in incidence of multiple sclerosis in women. This rapid change must have environmental origins even if it is associated with a gene-environment interaction, and implies that a large proportion of multiple sclerosis cases may be preventable in situ. Although the reasons why incidence of the disease is increasing are unknown, there are major implications for health-care provision because lifetime costs of multiple sclerosis exceed pound1 million per case in the UK.

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    • "ex differences in the incidence, onset, progression and outcome of brain disorders associated with neuroinflammation have been identified. Women have a higher risk of developing Alzheimer's disease (Andersen et al., 1999; Fratiglioni et al., 1997), multiple sclerosis (Noonan et al., 2002; Orton et al., 2006; Schwendimann and Alekseeva, 2007) and other autoimmune diseases (Dooley and Hogan, 2003; Gleicher and Barad, 2007; Jacobson et al., 1997) than men. "
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    ABSTRACT: Several brain disorders associated with neuroinflammation show sex differences in their incidence, onset, progression and/or outcome. The different regulation of the neuroinflammatory response in males and females could underlie these sex differences. In this study, we have explored whether reactive gliosis after a penetrating cortical injury exhibits sex differences. Males presented a higher density of Iba1 immunoreactive cells in the proximity of the wound (0-220 μm) than females. This sex difference was due to a higher number of Iba1 immunoreactive cells with nonreactive morphology. In addition microglia/macrophages in that region expressed arginase-1, marker of alternatively activated microglia, and the neuroprotective protein Neuroglobin, in a greater proportion in males than in females. No sex differences were found in the number of astrocytes around the lesion. However, the percentage of astrocytes expressing chemokine (C-C motif) ligand 2 (CCL2), involved in recruitment of immune cells and gliosis regulation, was higher in males. Males also presented a significantly higher density of neurons in the lesion edge than females. These findings indicate that male and female mice have different neuroinflammatory responses after a cortical stab wound injury and suggest that sex differences in reactive gliosis may contribute to sex differences in neuroinflammatory diseases. GLIA 2015. © 2015 Wiley Periodicals, Inc.
    Glia 06/2015; 63(11). DOI:10.1002/glia.22867 · 6.03 Impact Factor
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    • "MS has a great social and economic impact, because it affects mainly young adults [5], who will be more prone to unemployment [6] and in a big percentage will need a walking aid few years after the disease onset [7] [8]. MS is more prevalent in females [9] and Caucasians [10] and it is influenced by the geographic localization (Multiple Sclerosis International Federation). "
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    ABSTRACT: Multiple Sclerosis (MS) is a chronic autoimmune disease of the Central Nervous System causing inflammation and neurodegeneration. There are only 3 epidemiological studies in Portugal, 2 in the Centre and 1 in the North, and there is the need to further study MS epidemiology in this country. The objective of this work is to contribute to the MS epidemiological knowledge in Portugal, describing the patients' epidemiological, demographic, and clinical characteristics in the Braga district of Portugal. This is a cross-sectional study of 345 patients followed in two hospitals of Braga district. These hospitals cover a resident population of 866,012 inhabitants. The data was collected from the clinical records, and 31/12/2009 was established as the prevalence day. For all MS patients, demographic characteristics and clinical outcomes are reported. We have found an incidence of 2.74/100,000 and a prevalence of 39.82/100,000 inhabitants. Most patients have an EDSS of 3 or lower and a mean age of 42 years. The diagnosis was done at mean age of 35, with RRMS being the disease type in more than 80% of patients. In this cohort, we found a female : male ratio of 1.79. More than 50% of patients are treated with Interferon β-1b IM or IFNβ-1a SC 22 μg.
    Neurology Research International 01/2015; 2015:895163. DOI:10.1155/2015/895163
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    • "6–3.2 to 1 reported in some regions of Europe and North America [38] [39] "
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    ABSTRACT: The Latin American MS Experts’ Forum has developed practical recommendations on the initiation and optimization of disease-modifying therapies in patients with relapsing-remitting multiple sclerosis (RRMS). The recommendations reflect the unique epidemiology of MS and the clinical practice environment in Latin American countries. Treatment response may be evaluated according to changes in relapses; progression, as assessed by the Expanded Disability Status Scale and the Timed 25-foot Walk; and lesion number on magnetic resonance imaging. Follow-up assessments are recommended every six months, or annually for stable patients. Cognitive function should be evaluated in all RRMS patients at baseline and annually thereafter. These recommendations are intended to assist clinicians in Latin America in developing a rational approach to treatment selection and sequencing for their RRMS patients.
    Journal of the neurological sciences 04/2014; 339(1-2). DOI:10.1016/j.jns.2014.02.017 · 2.47 Impact Factor
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