A disease found on the South Pacific island of Guam may shed light
on how Alzheimer’s disease develops, according to a team of researchers
led by UBC neuroscientist Dr. Pat McGeer and Canadian neurologist
Dr. John Steele in Guam.
The disease, which resembles Alzheimer’s and Parkinson’s and is
known as Parkinsonism-dementia complex, may be linked to genes,
not toxins in the diet as was previously believed.
Earlier theories suggested the disease, which leads to dementia
and is called Bodig, had been caused by eating the toxic seeds of
the false sago palm, or by dietary imbalances of calcium and magnesium.
Despite dietary corrections, the disease is still prevalent in
the families of the Chamorro, Guam’s indigenous people, making a
genetic cause more likely. Deaths from Bodig in the past five years
are the second highest ever recorded, say the researchers.
“In my 15 years of practice on Guam, all the cases I have seen
have been of native Chamorro origin,” says Steele. “If toxins were
involved, frequent non-Chamorro cases should have appeared since
that group is now a minority population on Guam.”
The researchers found that abnormalities known as neurofibrillary
tangles, which affect the brain cells that transmit nerve impulses
and are characteristic of Alzheimer’s, are present in both illnesses.
In cases of Bodig, however, there are no senile plaques — lesions
also characteristic of Alzheimer’s.
“This means that tangles alone can produce dementia,” says McGeer.
“Identification of a dominant gene which produces Alzheimer’s disease-like
tangles will shed great light on how the disease develops.”
McGeer says that the lesions of the syndrome found in Guam also
show many of the same inflammatory changes seen in Alzheimer’s disease.
Anti-inflammatory therapy might be beneficial for the Chamorro patients.
Previous studies conducted by McGeer and fellow researcher Edith
McGeer into Alzheimer’s suggest that anti-inflammatory drugs may
slow the progress of the disease.
Alzheimer’s, a degenerative brain disorder associated with aging,
currently affects 250,000 Canadians and costs Canadian taxpayers
almost $4 billion annually to manage.
Steele is well known for his co-discovery of Steele-Richardson-Olszewski
syndrome, a major illness which resembles Parkinson’s disease. Other
members of the research team were UBC Prof. Emerita Edith McGeer,
Claudia Schwab of UBC’s neurological laboratory, the Kinsmen Laboratory
of Neurological Research, and Dr. Robert Haddock of Guam.
The team’s findings are published in the August issue of Neurology,
the official journal of the American Academy of Neurology.
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