2 Parents With Alzheimer's, Higher Risk of This?
Small study found these people had more beta-amyloid deposits, less gray matter
It has long been known that a rare form of the disease that arises before age 65, called early onset familial Alzheimer's, is caused by genetic mutations passed from parent to child.
But, Kanner said, this latest research suggests there is also a genetic component to the more common "late-onset" Alzheimer's.
Studies have found that older adults who had a parent with Alzheimer's have a higher risk of developing it than those with two unaffected parents. And the risk is higher still when both parents had Alzheimer's.
Fortunately, that situation affects less than 5 percent of adults, Mosconi said.
But, she said, it might be wise to include those individuals in future studies testing ways to prevent Alzheimer's.
For the current study, Mosconi's team recruited 52 healthy adults to undergo MRI and PET scans of the brain. They were split evenly into four groups of 13: those with two parents who had Alzheimer's, those with an affected mother, those with an affected father and those with two Alzheimer's-free parents.
Overall, the study found, the group with two affected parents showed more Alzheimer's-linked brain abnormalities. They had, for example, 5 percent to 10 percent more beta-amyloid deposits than the other three groups. They also showed the lowest volume of gray matter and a slower metabolism of glucose, the brain's main fuel.
In general, Mosconi said, the study saw a "parent-dose" pattern: People with two Alzheimer's-affected parents had the highest level of disease indicators, followed by people whose mother was affected, and then those with an affected father.
Another expert said the finding of a higher risk in the mother-only group is interesting.
Past research has suggested that people's risk of Alzheimer's might be higher when a mother, rather than a father, was affected, said Jeremy Silverman, a professor of psychiatry at the Mount Sinai Icahn School of Medicine in New York City.
If that's true, it could offer hints about the genetic roots of Alzheimer's, he said. There is, for example, a type of DNA -- called mitochondrial DNA -- that's inherited only from mothers.