Why family history ups Alzheimer's risk - especially from the maternal side

Washington, March 16 : Previous studies have shown that the incidence of Alzheimer's is higher among those whose parents were diagnosed with the memory-robbing disease. Now, scientists have found the likely basis for this heightened familial risk—especially from the maternal side.

With the help of a new version of a brain scanning technique, an international collaboration led by NYU Langone Medical Center researchers discovered a far greater number of protein clumps linked to the disease among healthy adult children of parents with Alzheimer''s compared to counterparts with no family history of dementia.

The average increase in these clumps, called amyloid-beta plaques, was particularly striking among study volunteers whose mothers had been diagnosed with the disease. The plaques appeared throughout most regions of the brain.

The study examined 42 healthy individuals, including 14 whose mothers had Alzheimer''s, 14 whose fathers had Alzheimer''s, and 14 counterparts with no family history of the disease.

On average, the first group of volunteers showed a 15 percent higher burden of amyloid-beta deposits than those with a paternal family history, and a 20 percent higher burden of the protein clumps than those with no familial risk factors.

The new findings may help explain why a family history is such a big risk factor for the brain disease—individuals with an affected parent have a four- to ten-fold greater risk than those with no family history.

The study has been published in the March 15, 2010, online early edition of Proceedings of the National Academy of Sciences.