Tales of Pacific tangles

Abstract

The Chamorros (meaning “chief”), the native people of Guam, came to the Marianas, an archipelago of small mixed volcanic and limestone islands of Micronesia, around 1500 BC. After the end of the Second World War, two unusual conditions were reported with a high prevalence in the Chamorros.1,2 First was amyotrophic lateral sclerosis (ALS) with a relatively early age at onset, and the second was an unusual parkinsonism-dementia complex (PDC). ALS and PDC at times coexisted in the same person. Over the past 50 years, the prevalence of Guamanian ALS declined, as did the prevalence of PDC, although less so. Concurrently there emerged an increased incidence of late-life dementia without parkinsonism, with a phenotype similar to that of Alzheimer disease (AD). However, the pathology was distinct: tauopathy (hyperphosphorylated microtubule associated TAU protein) with neurofibrillary tangles occurred often without neuritic plaques, and not both pathologies together, as usually seen in AD. Consequently, this disorder has been termed Guamanian dementia (GD). Alpha synuclein pathology was also seen, especially with PDC. The temporal trends in the prevalence of Guamanian neurodegenerative diseases (NDD) and the rarity of the diseases in Chamorro populations on other islands suggested the operation of environmental factors, with those most heavily exposed developing ALS, those with intermediate levels of exposure developing PDC, and those with the least exposure developing GD. Studying the dietary habits of the Chamorros, Marjorie Whiting, a cultural anthropologist and nutritionist, …