Amyotrophic Lateral Sclerosis and Parkinsonism-Dementia Complex of Guam: Changing Incidence Rates during the Past 60 Years

• Published in: American journal of epidemiology Vol. 157; no. 2; pp. 149 - 157
• Main Authors: Plato, Chris C., Garruto, Ralph M., Galasko, Douglas, Craig, Ulla-Katrina, Plato, Meropi, Gamst, Anthony, Torres, Jose M., Wiederholt, Wigbert
• Format: Journal Article
• Language: English
• Published: Cary, NC Oxford University Press 15-01-2003; Oxford Publishing Limited (England)
• Subjects: Adult; Age Distribution; Aged; ALS; amyotrophic lateral sclerosis; Amyotrophic Lateral Sclerosis - epidemiology; Biological and medical sciences; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; dementia; Dementia - complications; Dementia - epidemiology; Female; Guam - epidemiology; Humans; Incidence; Male; Medical sciences; Middle Aged; National Institute of Neurological Disorders and Stroke; Neurology; NINDS; Parkinson Disease - complications; Parkinson Disease - epidemiology; parkinsonian disorders; parkinsonism-dementia complex; PDC; Sex Distribution; Tropical medicine; Guam; Micronesia; Mariana Islands; Oceania; Human; Nervous system diseases; Amyotrophic lateral sclerosis; Epidemiology; parkinsonian disorders; Cerebral disorder; Incidence; Central nervous system disease; Guam Parkinson dementia; dementia; Degenerative disease; Spinal cord disease; Public health; Extrapyramidal syndrome
• ISSN: 0002-9262; 1476-6256; 0002-9262
• DOI: 10.1093/aje/kwf175

In the 1950s, the incidence of amyotrophic lateral sclerosis (ALS, or Lytico) and parkinsonism-dementia complex (PDC, or Bodig) on the island of Guam was much higher than anywhere else in the world. From the late 1960s to the early 1980s, the incidence of both disorders has decreased. The objective of the present study was to ascertain whether the decreasing incidence continued until the end of the century (1999). The average annual incidence of ALS and PDC was calculated for each 5-year period from 1940 to 1999, utilizing registration records of all ALS and PDC cases on Guam during that period. The results of this study confirmed that the incidence of ALS declined steadily during the past 40 years. The incidence of PDC also declined until the late 1980s but, unlike ALS, showed a slight increase from 1980 to 1999. The rapid decrease in incidence is not likely to be due to genetic factors. Instead, it is most likely to be the results of radical socioeconomic, ethnographic, and ecologic changes brought about by the rapid westernization of Guam.