People who don't go on to develop dementia and have high levels of a certain protein that indicates the presence of inflammation have relatives who are also likely to resist dementia, according to a new study.

"In very elderly people with good cognition, higher levels of C-reactive protein, which is related to inflammation, are associated with better memory," study author Jeremy Silverman, of Mount Sinai School of Medicine in New York, said in a news release.

"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," he added.

The study, published online in the medical journal Neurology, consisted of 277 male veterans aged 75 and older and free of dementia symptoms. 

Researchers measured levels of the protein in participants and then interviewed participants to see whether the participants' parents and siblings had dementia. The researchers found that a  40 relatives, of the total 1,329, had dementia.

In a second independent group made up of 51 men, age 85 and older, with no dementia symptoms were also interviewed to determine whether their relatives had dementia and only nine of the 202 relatives had dementia.

Study authors found that participants who had higher amounts of the C-reactive protein were more than 30 percent less likely to have relatives with dementia. Researchers said that similar results were also found in the second older group.

Researchers concluded that because he protein levels were not associated with years of education, marital status, occupation and physical activity, these factors could not account for the lower dementia risk seen in the relatives of participants.

"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," said Silverman. "Our study shows that this protection may be passed on to immediate relatives."