Tangled theories for high incidence of MND on Pacific Rim
30 November 2006
Two rare but possibly connected forms of Motor Neurone Disease that only affect people living on the Pacific Rim came under the spotlight at the opening session of the 17th International Symposium on ALS/MND.
An unusual form of MND, known as ALS-PDC, which brings on symptoms of MND, dementia and Parkinson’s Disease, affects a relatively high number of people on the Pacific island of Guam. A similar condition affects families on Japan’s Kii Peninsula. Both conditions are caused by neuro-filament tangles (NFTs) that arise in the central nervous system.
Delegates were told that a complex combination of genetic and environmental factors are likely to account for the high number of cases found on Guam, and that a previous hypothesis based around the islanders’ consumption of fruit bats now looked unlikely to be the cause of the high case numbers.
Dr Douglas Galasko, of the University of California, said pathological research had disproved the theory that the high incidence might be caused by high concentrations of a neurotoxin found in cycad fruit on the island that are eaten by fruit bats, which in turn are eaten by the islanders.
He said there did seem to be a link with toxins contained in flour made from cycad fruit, but as cycad flour is eaten throughout the world, it was likely there was also a genetic factor that uniquely affected the inhabitants of Guam.
Also, cycad flour and fruit bats do not appear in the diets of people living in the Kii Peninsula, where a genetic risk factor was most likely to account for the higher than average MND case numbers.
This was the conclusion of Dr Shigeki Kuzuhara, from Mie University in Japan, who has studied cases of MND in the Kii Peninsula. He found that a family history was the greatest risk factor in determining who developed this rare version of the disease.
Further research is planned to understand the risk factors involved, and what this can tell us about the cause of the more widespread, common form of MND.
An unusual form of MND, known as ALS-PDC, which brings on symptoms of MND, dementia and Parkinson’s Disease, affects a relatively high number of people on the Pacific island of Guam. A similar condition affects families on Japan’s Kii Peninsula. Both conditions are caused by neuro-filament tangles (NFTs) that arise in the central nervous system.
Delegates were told that a complex combination of genetic and environmental factors are likely to account for the high number of cases found on Guam, and that a previous hypothesis based around the islanders’ consumption of fruit bats now looked unlikely to be the cause of the high case numbers.
Dr Douglas Galasko, of the University of California, said pathological research had disproved the theory that the high incidence might be caused by high concentrations of a neurotoxin found in cycad fruit on the island that are eaten by fruit bats, which in turn are eaten by the islanders.
He said there did seem to be a link with toxins contained in flour made from cycad fruit, but as cycad flour is eaten throughout the world, it was likely there was also a genetic factor that uniquely affected the inhabitants of Guam.
Also, cycad flour and fruit bats do not appear in the diets of people living in the Kii Peninsula, where a genetic risk factor was most likely to account for the higher than average MND case numbers.
This was the conclusion of Dr Shigeki Kuzuhara, from Mie University in Japan, who has studied cases of MND in the Kii Peninsula. He found that a family history was the greatest risk factor in determining who developed this rare version of the disease.
Further research is planned to understand the risk factors involved, and what this can tell us about the cause of the more widespread, common form of MND.
Contact:
Notes to editors
The 17th International Symposium on ALS/MND is taking place in Yokohama, Japan, between Thursday, 30 November and Saturday, 2 December. The event is organised by the UK-based Motor Neurone Disease (MND) Association and hosted this year by the Japanese ALS Association (JALSA).
- Read the abstracts from Session 1 Opening Session (36kb - PDF)
