Latitudinal variation in incidence and type of first central nervous system demyelinating events.


Journal Article

Increasing prevalence and variable geographic patterns of occurrence of multiple sclerosis suggest an environmental role in causation. There are few descriptive, population-level, data on whether such variability applies to first demyelinating events (FDEs). We recruited 216 adults (18-59 years), with a FDE between 1 November 2003 and 31 December 2006 in a multi-center incident case-control study in four locations on the south-eastern and eastern seaboard of Australia, spanning latitudes 27 degrees south to 43 degrees south. Population denominators were obtained from the Australian Bureau of Statistics censuses of 2001 and 2006. Age and sex adjusted FDE incidence rates increased by 9.55% (95% confidence interval (CI) 7.37-11.78, p < 0.001) per higher degree of latitude. The incidence rate gradient per higher degree of latitude varied by gender (male: 14.69% (95% CI 9.68-19.94, p < 0.001); female 8.13% (95% CI 5.69-10.62, p < 0.001)); and also by the presenting FDE type: optic neuritis 11.39% (95% CI 7.15-15.80, p < 0.001); brainstem/cerebellar syndrome 9.47% (95% CI 5.18-13.93, p < 0.001); and spinal cord syndrome 5.36% (95% CI 1.78-9.06, p = 0.003). Differences in incidence rate gradients were statistically significant between males and females (p = 0.02) and between optic neuritis and spinal cord syndrome (p = 0.04). The male to female ratio varied from 1 : 6.7 at 27 degrees south to 1 : 2.5 at 43 degrees south. The study establishes a positive latitudinal gradient of FDE incidence in Australia. The latitude-related factor(s) influences FDE incidence variably according to subtype and gender, with the strongest influence on optic neuritis presentations and for males. These descriptive case analyses show intriguing patterns that could be important for understanding the etiology of multiple sclerosis.

Full Text

Cited Authors

  • Taylor, BV; Lucas, RM; Dear, K; Kilpatrick, TJ; Pender, MP; van der Mei, IAF; Chapman, C; Coulthard, A; Dwyer, T; McMichael, AJ; Valery, PC; Williams, D; Ponsonby, A-L

Published Date

  • April 2010

Published In

Volume / Issue

  • 16 / 4

Start / End Page

  • 398 - 405

PubMed ID

  • 20167594

Pubmed Central ID

  • 20167594

Electronic International Standard Serial Number (EISSN)

  • 1477-0970

International Standard Serial Number (ISSN)

  • 1352-4585

Digital Object Identifier (DOI)

  • 10.1177/1352458509359724


  • eng