WEDNESDAY, Sept. 10, 2014 (HealthDay News) -- Your blood type may play a small role in your risk for dementia, a new study finds.

People with blood type AB, which includes about 4 percent of the population, appear to have an increased risk for memory problems as they age. Over about three years, individuals with blood type AB were almost twice as likely to show memory problems as those with type O blood, the most common blood group, the study found.

But experts cautioned that those with AB blood shouldn't panic because other circumstances play a bigger part in their risk for mental impairment.

"If you were to do the same study and look at smoking, lack of exercise, obesity and other lifestyle factors, the risk of dementia is much, much higher," said Dr. Terence Quinn, a clinical lecturer in stroke and geriatric medicine at the University of Glasgow in Scotland. "People who are worried about dementia, whether they have that blood group or not, should look at making those lifestyle changes."

In the study, researchers gave more than 30,000 people, aged 45 and older, a series of memory and thinking skills tests and then tested them again a little more than three years later. From this group, 495 participants scored low enough to qualify as having some memory or thinking impairment, and their blood types were compared to those of 587 participants with normal cognitive (mental) scores.

After making adjustments for differences in the participants' age, race, sex and geographical region, those who had AB blood types were 82 percent more likely to have impaired thinking skills than those with type O blood, according to the study.

Yet these findings, published online Sept. 10 in the journal Neurology, aren't necessarily surprising considering other recent research, said the study's senior researcher, Dr. Mary Cushman, a professor of hematology at the University of Vermont College of Medicine. It's already known that having blood type AB can affect blood clotting characteristics and risk of blood vessel-related conditions, she said. In addition, her research group found earlier this year that the AB blood type was linked to a higher risk of stroke.