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  • Updated 02.20.2023
  • Released 09.02.1994
  • Expires For CME 02.20.2026

ALS-like disorders of the Western Pacific



Following World War II, extremely high rates of a neurodegenerative disease with features of amyotrophic lateral sclerosis, 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. In Guam, incidence rates of ALS-PDC have declined dramatically over subsequent decades, with a change in phenotype to predominantly dementia. Although the definitive etiology is still unknown, the cause of ALS-PDC is most likely related to an environmental exposure.

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 three cultures utilized cycad seeds for medicinal sources, or food sources, or both; 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.

Historical note and terminology

Guam, the largest of the Mariana Island archipelago in the Western Pacific, was ceded to the United States by Spain in 1898 after a long history of European colonialism. The island was captured by the Japanese in 1941 during World War II and was recaptured in 1944 and established as an organized territory of the United States. The military installation on the island is one of the most strategically important U.S. bases in the Pacific.

During this time, it was noted that Guam, together with the Kii peninsula of Japan and the Auyu and Jaqai cultural groups of West Papua, Indonesia, had one of the highest incidences of amyotrophic lateral sclerosis (ALS), parkinsonism, and dementia in the world (03; 44). This complex of neurodegenerative diseases was termed lytico-bodig by the indigenous Chamorro people of Guam (lytico derived from the Spanish word for weakness, bodig referring to a family with parkinsonism and dementia who worked at a bodega or market), and Moro disease within the Kii peninsula; it is known elsewhere as amyotrophic lateral sclerosis-parkinsonism-dementia complex (ALS-PDC) (46). ALS-PDC, or lytico-bodig, has been known to the Chamorro people for over 180 years.

In the two decades following WWII, ALS-PDC incidence, prevalence, and mortality rates in the Chamorro population of Guam was 50 to 100 times that of sporadic amyotrophic lateral sclerosis in other areas of the world, and at one time was the Chamorro's leading cause of death (03; 44; 74; 49). The high prevalence of ALS-PDC facilitated the study of neurodegenerative diseases throughout the world. Hirano and colleagues first defined ALS-PDC of Guam (33), and the identification of the Hirano body in this population has contributed to recognition and investigation of classic amyotrophic lateral sclerosis, Alzheimer disease, and Parkinson disease (34). However, no clearly defined etiologic agent has been identified, and because of a decline in reported new cases of ALS-PDC, the Guam research outpost was closed in 1985 (27; 46).

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