Cycad exposure and risk of dementia, MCI, and PDC in the Chamorro population of Guam

Neurology. 2007 May 22;68(21):1764-71. doi: 10.1212/01.wnl.0000262027.31623.b2.


Objective: To study cycad-derived products as possible risk factors for dementia, mild cognitive impairment (MCI), and parkinsonism-dementia complex (PDC) on Guam.

Methods: Complete risk factor data from in-person interviews of 166 cases of Guam dementia, 50 cases of amnestic MCI, and 21 cases of PDC were compared with 1,581 controls in the base population regarding exposure to cycad-derived products from a traditional food (fadang), consumption of fruit bats, and use of cycad-derived topical medicine.

Results: Adjusted odds ratios (ORs) and 95% CIs for picking, processing, and eating fadang in young adulthood ranged from 1.42 (1.05 to 1.91) to 2.87 (1.48 to 5.56) and were consistently elevated and significant across all three diagnostic outcomes. Associations independent of exposure in young adulthood were for picking (OR 0.78, 95% CI 0.64 to 0.96) and processing (OR 0.77, 95% CI 0.63 to 0.94) fadang in childhood with Guam dementia. Men showed stronger and more consistent relations across exposure groups in young adulthood compared with women. No associations were found for consumption of fruit bats or exposure to cycad used as a topical medicine for any of the outcomes. Estimated adjusted population attributable risks suggest that exposure to eating fadang in young adulthood incurred the highest attributable risk percent.

Conclusions: Environmental lifestyle and diet may contribute to the etiology of neurodegenerative diseases in the native population of Guam.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Age Factors
  • Aged
  • Aged, 80 and over
  • Animals
  • Brain / drug effects
  • Brain / metabolism
  • Brain / physiopathology
  • Chiroptera / metabolism
  • Cognition Disorders / chemically induced*
  • Cognition Disorders / diagnosis
  • Cognition Disorders / ethnology
  • Cohort Studies
  • Cycas / adverse effects*
  • Dementia / chemically induced*
  • Dementia / diagnosis
  • Dementia / ethnology
  • Environmental Exposure / adverse effects*
  • Feeding Behavior
  • Female
  • Guam / epidemiology
  • Humans
  • Male
  • Oceanic Ancestry Group / statistics & numerical data
  • Parkinsonian Disorders / chemically induced*
  • Parkinsonian Disorders / diagnosis
  • Parkinsonian Disorders / ethnology
  • Plant Extracts / adverse effects*
  • Prevalence
  • Risk Factors
  • Sex Factors
  • Time


  • Plant Extracts