People who carry a certain
genetic mutation associated with Alzheimer's
disease have double the rate of debilitating brain-tissue loss, a new study
People with this mutation,
known as the TREM2 gene variant, may also develop the disease three years
earlier than expected, the researchers said.
"Our lab studies the
rate of brain-tissue loss in elderly people, trying to discover factors that
protect you as you age. We have never seen such a dramatic effect as with this
genetic variant," study lead author Paul Thompson, a professor of
neurology at the University of Southern California, said in a news release.
Wildfire of tissue loss
"If you carry this
genetic mutation, we've found that there is this wildfire of tissue loss in the
brain," he said.
In the study, the
researchers mapped the effects of the gene mutation on the living brain using
MRI scans. "This is the first study to use brain scans to show what this
gene variant does, and it's very surprising," Thompson said.
The two-year study,
published in The New England Journal of Medicine, showed that
people with the TREM2 gene variant associated with Alzheimer's lose their brain
tissue much more quickly.
The research involved
nearly 500 adults from North America, averaging 76 years of age. One hundred
had Alzheimer's disease, 221 had some impairment in memory or thinking, and 157
People with the gene
mutation lost 1.4% to 3.3% more of their brain tissue than those who did not
carry the mutation. This more extensive brain loss, which took place primarily
in areas of the brain responsible for memory, also proceeded twice as quickly
in those with the mutation.
Silent time bomb
"This gene speeds up
brain loss at a terrific pace," Thompson said. "Carriers of this
genetic mutation, who comprise about 1% of the population, lose about 3% of
their brain tissue per year. This is a silent time bomb in 1% of the
Although healthy people
usually lose less than 1% of their brain tissue per year, this loss is
offset by the creation of new normal tissue from mental stimulation. For those
with Alzheimer's, however, symptoms typically appear once about 10% of
their brain tissue has been destroyed.
Thompson's team said the
findings might have real importance in speeding research into effective
Alzheimer's treatments because if studies targeted people who carry this
mutation, answers to vital questions might become apparent more quickly.
people who carry the mutation in clinical trials for Alzheimer's treatments
could help us reach quicker and more meaningful results," Thompson said.
The US National Institute
on Ageing provides more information on Alzheimer's disease.