A study of brain scans has confirmed the role of several genes linked with Alzheimer's disease, and turned up two others that are worth exploring, U.S. researchers said on Monday.
A team at Massachusetts General Hospital in Boston used magnetic resonance imaging or MRI scans to study changes in brain structures -- such as the size of the hippocampus and amygdala -- in 700 healthy volunteers and Alzheimer's patients.
They used computer programs to sort through the genetic sequences of the 700 volunteers to see which gene mutations are most linked with these changes.
The study turned up a known offender -- the APOE4 gene -- as the most strongly linked with the disease, but it also confirmed three other genes -- CLU, CRI, PICALM -- that have been more recently linked with Alzheimer's.
And they fingered two others -- BIN1 and CNTN5 -- which have been suspected, but not strongly linked with Alzheimer's.
While the findings are preliminary, "they may help prioritize targets for future genetic studies," Drs. Alessandro Biffi and Christopher Anderson of Massachusetts General and the Broad Institute wrote in the Archives of Neurology.
Researchers suspect genes can explain 60 to 80 percent of the risk of late onset Alzheimer's disease, the kind that occurs with age.
Scientists have long understood the genetic cause of early onset Alzheimer's, a rare type that affects people under 60, but finding genes that explain the more common late onset form has been far more challenging.