Researchers studied sets of twins in which one twin developed Alzheimer's and the other didn't. They found that the twin with Alzheimer's was four times more likely to have had gum disease by middle age.
"While genetic factors are significant in explaining why some people develop dementia and others do not, our research suggests that there are certain risk factors over which an individual may be able to exert some influence earlier in his or her life," says researcher Margaret Gatz, professor of psychology at the University of Southern California, in a news release. "And these aren't risk factors that are unique to dementia. Many of these are also risk factors for other disorders."
The results of the study were presented this week at the Alzheimer's Association 1st International Conference on Prevention of Dementia.
Inflammation Linked to Dementia
In the study, researchers analyzed data from the Swedish Twin Registry that included information on 109 sets of twins in which one twin had Alzheimer's or other type of dementia and the other did not.
If one twin has Alzheimer's disease the other twin has a 60% chance of developing the disease.
In comparing the sets of twins, researchers found the twin with dementia was four times more likely to have had gum disease by midlife than the other.
Researchers say their results indicate an inflammatory burden early in life, such as chronic gum disease, may have a significant impact on the later risk of Alzheimer's disease and dementia. Previous studies have also linked inflammation to heart disease and stroke risk.
Education Not a Big Factor
Unlike previous studiesprevious studies, the researchers did not find education to be a strong factor in predicting risk of dementia.
Researchers say that the influence of education was not a huge risk factor after controlling for genetic risk factors.
But researchers say the results may call into question the idea that dementia and Alzheimer's disease are linked to mental inactivity.
They found that mental activities at age 40, like reading or attending cultural events, did not appear to lower the risk of developing Alzheimer's disease.
"We go around saying, 'Well, it can't hurt to do crossword puzzles.' There is a way it can hurt," she says. "The way it can hurt is if we start blaming the people who are demented for not exercising their brains enough, or overselling activities that could make a difference where it's really unsubstantiated. I think we have got to be real careful in our messages about risk reduction," says Gatz.