With more than 5 million Americans suffering from Alzheimer's
disease, the most common form of dementia, the race is on to
surface clues about causes and prevention. An important
breakthrough for the research field comes in the journal Nature
this week. Researchers say they found a rare genetic mutation in
Iceland that appears to protect against Alzheimer's disease. The
mutation appears to slow the production of the beta-amyloid
protein, long considered to be a cause of Alzheimer's. This
mechanism helps validate the theory that beta-amyloid plaques --
an accumulation of the protein - cause this form of dementia for
which no cure has been found. The research team was led by Dr.
Kari Stefansson, chief executive of the Icelandic company DeCode
Genetics. They studied data from the genomes of nearly 1,800
Icelandic people. A genetic test for the protective mutation
wouldn't make sense, since it's so rare, experts said. It's
quite possible that this mutation is exclusive to the Icelandic
population. Mutations like