WEDNESDAY, Aug. 15, 2012 (HealthDay News) -- Resistance to dementia may run in families, according to a new study.
Researchers found parents and siblings of people with normal brain function and high levels of a protein related to inflammation have a lower risk for dementia.
"In very elderly people with good cognition, higher levels of C-reactive protein, which is related to inflammation, are associated with better memory," said study author Jeremy Silverman, a professor in the psychiatry department at Mount Sinai School of Medicine in New York City. "Our results found that the higher the level of this protein in the study participant, the lower the risk for dementia in their parents and siblings."
In conducting the study, published online Aug. 15 in the journal Neurology, the researchers identified nearly 300 men aged 75 and older with no symptoms of dementia. The men received a test to measure their level of C-reactive protein, and they were asked questions about their parents and siblings -- more than 1,300 in all -- to determine how many had dementia. They determined that 40 relatives from 37 families had dementia.
The researchers then identified and questioned 51 men aged 85 and older with no dementia symptoms. Of roughly 200 relatives the researchers asked about, nine had dementia.
The researchers said the men in the first group who had higher levels of the protein were more than 30 percent less likely to have a relative with dementia. Similar results were found in the second group.
The researchers noted that outside factors, such as education, marital status and physical activity, did not play a role in the relatives' reduced risk since they were not linked to the men's protein levels.
"This protein is related to worse cognition in younger elderly people. Thus, for very old people who remain cognitively healthy, those with a high protein level may be more resistant to dementia," Silverman said in a journal news release. "Our study shows that this protection may be passed on to immediate relatives."
Although the study found a connection between higher levels of the protein and lower rates of dementia in family members, it did not necessarily prove a cause-and-effect relationship.
The U.S. National Institutes of Health provides more information on dementia.