title: Clinical features and changing patterns of neurodegenerative disorders on Guam, 1997-2000.
abstract: BACKGROUND
  In the 1950s, high-incidence ALS and Parkinson-dementia complex (PDC) were identified among Chamorros, the native inhabitants of Guam. Brains of patients with these syndromes showed widespread neurofibrillary tangles. Although ALS and PDC were reported to have dramatically declined in the 1980s, new cases are still encountered. Late-life dementia has received little study among Chamorros.
  
  
  METHODS
  From 1997 to 2000, the authors evaluated newly referred and previously identified patients. They screened first-degree relatives of previous registries, and subjects aged 60 or older. Subjects who scored below a cognitive test cutoff or had symptoms or signs consistent with parkinsonism or ALS underwent psychometric testing, assessment by a neurologist, and laboratory studies as appropriate. Consensus diagnoses were made.
  
  
  RESULTS
  The authors identified 194 Chamorros with ALS (n = 10), PD (n = 11), PDC (n = 90), or late-life dementia (n = 83). Mean ages at onset were 55 for ALS, 68 for PDC, 63 for PD, and 74 for dementia. Late-life dementia was more common in women, and met criteria for probable or possible AD. The APOE-epsilon 4 allele frequency was uniformly low regardless of neurologic diagnosis.
  
  
  CONCLUSIONS
  The rapid decline of high-incidence ALS on Guam over the past 40 years suggests the contribution of a modifiable environmental factor. PDC remains relatively common, with an unchanged clinical picture apart from later age at onset. Dementia among elderly Chamorros (termed "Mariana dementia") resembles AD. Autopsy studies will clarify whether this dementia is related to AD pathology or represents a late-life neurofibrillary tangle syndrome more closely allied to PDC.
authors.affiliation: Department of Neurosciences, University of California, San Diego, USA. dgalasko@ucsd.edu
authors.forename: D
authors.initials: D
authors.lastname: Galasko
authors.forename: D P
authors.initials: DP
authors.lastname: Salmon
authors.forename: U-K
authors.initials: UK
authors.lastname: Craig
authors.forename: L J
authors.initials: LJ
authors.lastname: Thal
authors.forename: G
authors.initials: G
authors.lastname: Schellenberg
authors.forename: W
authors.initials: W
authors.lastname: Wiederholt
mesh_terms: D017668:Age of Onset; D000368:Aged; D004777:Environment; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D006141:Guam / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D019636:Neurodegenerative Diseases / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology