ALS-like disorders of the Western Pacific

Introduction
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By Tracie Caller MD MPH

ALS-like disorders of the Western Pacific are also known as or subsume Amyotrophic lateral sclerosis-parkinsonism-dementia complex, Guam neurodegeneration, Lytico-bodig, and Marianas dementia. -ed.

Following World War II, extremely high rates of a neurodegenerative disease with features of amyotrophic lateral sclerosis (ALS), dementia, and Parkinson disease were described in the Western Pacific islands of Guam, the Kii peninsula of Japan, and West Papua, Indonesia. Termed lytico-bodig by natives, amyotrophic lateral sclerosis-parkinsonism-dementia complex (ALS-PDC) has distinct neuropathologic features of widely distributed neurofibrillary tangles comprised of tau in addition to pathologic findings of amyotrophic lateral sclerosis. Incidence rates have declined dramatically over subsequent decades, with a change in phenotype to predominantly dementia. The etiology of ALS-PDC is most likely a combination of environmental agents coupled with genetic susceptibility.

Key Points

  • Amyotrophic lateral sclerosis-parkinsonism-dementia complex (ALS-PDC), also known as lytico-bodig, is an endemic neurodegenerative disorder of the Western Pacific islands, known to occur only in the islands of the Guam archipelago, the Kii peninsula of Japan, and West Papua, Indonesia.
  • It is a slowly progressive degenerative disease with a spectrum of clinical presentation that can include features of amyotrophic lateral sclerosis, parkinsonism, and dementia.
  • The sharp decline in disease prevalence, increasing age of onset, and change in disease phenotype argue for an environmental etiology.
  • All 3 cultures utilized cycad seeds for medicinal and/or food sources; the cycad-derived toxin cycasin as well as the neurotoxic nonprotein amino acid beta-methyl-amino-L-alanine (BMAA) have been postulated as potential etiologies.
     

In This Article

Introduction
Historical note and nomenclature
Clinical manifestations
Etiology
Pathogenesis and pathophysiology
Epidemiology
Prevention
Differential diagnosis
Diagnostic workup
Prognosis and complications
Management
References Cited
Contributors