Neuroscientists have zeroed in on some target genes that may be tied to the development of Alzheimer's disease, and they've shown what abnormalities appear on brain scans of people with these genetic variations.
Both bits of scientific progress are incremental steps toward understanding what causes the disease that afflicts more than 5 millon Americans. The study, lead by researchers in Boston and Cambridge, Mass., England and Wales, appears in this month's Archives of Neurology.
"The drought of genetic findings in Alzheimer's disease has lasted a long time," write scientists based in London and Wales in an editorial accompanying the Archives study. "These findings, and the genome-wide studies that presaged them, mark a new period of optimism for those of us who study the etiologies of complex diseases of the nervous system."
The study explains the association researchers made between genetic loci that are related to Alzheimer's disease and neuorimaging measures that are related to disease risk. (These measures include the volume of the hippocampus, amygdala and other brain structures.) They identify B1N1 and CNTN5 as additional specific locations of genetic variants on chromosomes, but say their findings warrant further study.
Just one genetic variant, known as APOE, has been shown to influence Alzheiemer's disease risk and age at onset, lead authors Drs. Alessandro Biffi and Christopher Anderson write in their background information.
Study participants included 168 people with probable Alzheimer's, 357 people with mild cognitive impairment, a precursor to Alzheimer's, and 215 people who were cognitively normal. "Our results indicate that APOE and other previously validated loci for Alzheimer's disease affect clinical diagnosis of Alzheimer's disease and neuroimaging measures associated with the disease," they write.
Will that bring us closer to genetic tests for Alzheimer's?
Somewhat, John Hardy, of the University College London Institute of Neurology, says in an email, "but I think this genetic determinism argument is oversold, frankly.
"About 5 percent of the population are at high risk. About 30 percent of the population are at a moderate risk, and about 65 percent are at lower risk. These numbers are little changed by the new data. And, this is not really so useful for genetic testing."
Both bits of scientific progress are incremental steps toward understanding what causes the disease that afflicts more than 5 millon Americans. The study, lead by researchers in Boston and Cambridge, Mass., England and Wales, appears in this month's Archives of Neurology.
"The drought of genetic findings in Alzheimer's disease has lasted a long time," write scientists based in London and Wales in an editorial accompanying the Archives study. "These findings, and the genome-wide studies that presaged them, mark a new period of optimism for those of us who study the etiologies of complex diseases of the nervous system."
The study explains the association researchers made between genetic loci that are related to Alzheimer's disease and neuorimaging measures that are related to disease risk. (These measures include the volume of the hippocampus, amygdala and other brain structures.) They identify B1N1 and CNTN5 as additional specific locations of genetic variants on chromosomes, but say their findings warrant further study.
Just one genetic variant, known as APOE, has been shown to influence Alzheiemer's disease risk and age at onset, lead authors Drs. Alessandro Biffi and Christopher Anderson write in their background information.
Study participants included 168 people with probable Alzheimer's, 357 people with mild cognitive impairment, a precursor to Alzheimer's, and 215 people who were cognitively normal. "Our results indicate that APOE and other previously validated loci for Alzheimer's disease affect clinical diagnosis of Alzheimer's disease and neuroimaging measures associated with the disease," they write.
Will that bring us closer to genetic tests for Alzheimer's?
Somewhat, John Hardy, of the University College London Institute of Neurology, says in an email, "but I think this genetic determinism argument is oversold, frankly.
"About 5 percent of the population are at high risk. About 30 percent of the population are at a moderate risk, and about 65 percent are at lower risk. These numbers are little changed by the new data. And, this is not really so useful for genetic testing."
Read the study in the Archives of Neurology.
The National Institute on Aging's fact sheet on Alzheimer's disease genetics.
The National Institute on Aging's fact sheet on Alzheimer's disease genetics.
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