Age of Onset and latitude

Higher latitude is significantly associated with an earlier age of disease onset in multiple sclerosis. Tao C, Simpson S Jr, van der Mei I, Blizzard L, Havrdova E, Horakova D, Shaygannejad V, Lugaresi A, Izquierdo G, Trojano M, Duquette P, Girard M, Grand’Maison F, Grammond P, Alroughani R, Terzi M, Oreja-Guevara C, Sajedi SA, Iuliano G, Sola P, Lechner-Scott J, Pesch VV, Pucci E, Bergamaschi R, Barnett M, Ramo C, Singhal B, LA Spitaleri D, Slee M, Verheul F, Fernández Bolaños R, Amato MP, Cristiano E, Granella F, Hodgkinson S, Fiol M, Gray O, McCombe P, Saladino ML, Sánchez Menoyo JL, Shuey N, Vucic S, Shaw C, Deri N, Arruda WO, Butzkueven H, Spelman T, Taylor BV; MSBase Study Group.J Neurol Neurosurg Psychiatry. 2016 Nov 3. pii: jnnp-2016-314013

BACKGROUND:Age at onset (AAO) in multiple sclerosis (MS) is an important marker of disease severity and may have prognostic significance. Understanding what factors can influence AAO may shed light on the aetiology of this complex disease, and have applications in the diagnostic process.
METHODS: The study cohort of 22 162 eligible patients from 21 countries was extracted from the MSBase registry. Only patients with MS aged ≥16 years were included. To reduce heterogeneity, only centres of largely European descent were included for analysis. AAO was defined as the year of the first symptom suggestive of inflammatory central nervous system demyelination. Predictors of AAO were evaluated by linear regression.
RESULTS: Compared with those living in lower latitudes (19.0-39.9°), onset of symptoms was 1.9 years earlier for those at higher latitudes (50.0-56.0°) (p=3.83×10-23). A reciprocal relationship was seen for ambient ultraviolet radiation (UVR), with a significantly increasing AAO for patients with MS per each quartile increment of ambient UVR (p=1.56×10-17). We found that the AAO of female patients was ∼5 months earlier than male patients (p=0.002). AAO of progressive-onset patients with MS were ∼9 years later than relapsing-onset patients (p=1.40×10-265).
CONCLUSIONS: An earlier AAO in higher latitude regions was found in this worldwide European-descent cohort and correlated inversely with variation in latitudinal UVR. These results suggest that environmental factors which act at the population level may significantly influence disease severity characteristics in genetically susceptible populations.

Not only is latitude associated with a great incidence of MS, it also indicates that the age of onset is sooner, suggesting that environments is a prime driver in susceptibility to MS and severity.
Suggesting that susceptibility is modifyable.

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    • You may be able to move to change your risk e.g. to a low latitude. We are seeing second generation children of immigrants with increasing MS, so by moving their parents have increased the risk to their children

  • I thought research was done years ago that showed higher latitude was associated with greater incidence of MS, except in communities with a fish-based diet. Did I imagine that?

    • Yes the further away from the equator the higher the risk, e.g. as used to the case in many countries with Norway being an odd on out because they eat fish. What this says is not only the farther you go from equatory the higher the risk but also when disease arrives it occurs earlier

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