title: Motor neuron disease on Guam: temporal occurrence, 1941-85.
abstract: Using a case registry, we investigated the temporal occurrence of motor neuron disease (MND) on Guam. MND with onset during 1941-85 was documented in 434 Chamorros and 9 non-Chamorro migrants who had lived on Guam before onset. Increased median age at onset and decreased age-adjusted incidence rates (since the early 1960s) were observed for Chamorros of both sexes. Our evidence about MND on Guam is consistent with: 1) The latent period duration has varied from years to decades; 2) With time, the exposure period or latent period, or both, have lengthened; 3) The high risk of acquiring the condition has been reduced since, at least, the early 1950s, and the most recent years of meaningful risk were the early to middle 1960s; 4) The critical age for acquiring the condition is in adolescence and adulthood; 5) Change of environment from Guam to overseas during childhood resulted in decreased risk of acquiring the condition.
authors.affiliation: Neuroepidemiology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892-9135, USA.
authors.forename: Z X
authors.initials: ZX
authors.lastname: Zhang
authors.forename: D W
authors.initials: DW
authors.lastname: Anderson
authors.forename: N
authors.initials: N
authors.lastname: Mantel
authors.forename: G C
authors.initials: GC
authors.lastname: Román
mesh_terms: D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D000368:Aged; D001921:Brain / Q000503:physiopathology; D015331:Cohort Studies; D004641:Emigration and Immigration; D005260:Female; D006141:Guam / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D016472:Motor Neuron Disease / Q000453:epidemiology* / Q000503:physiopathology; D012189:Retrospective Studies