Anemia, or low levels of red blood cells, may increase the risk of dementia, according to a study published in the July 31, 2013, online issue of Neurology®, the medical journal of the American Academy of Neurology.

“Anemia is common in the elderly and occurs in up to 23 percent of adults ages 65 and older,” said study author Kristine Yaffe, MD, with the University of California – San Francisco and a member of the American Academy of Neurology. “The condition has also been linked in studies to an increased risk of early death.”

For the study, 2,552 older adults between the ages of 70-79 were tested for anemia and also underwent memory and thinking tests over 11 years. Of those, 393 had anemia at the start of the study. At the end of the study, 445, or about 18 percent of participants, developed dementia.

The research found that people who had anemia at the start of the study had a nearly 41 percent higher risk of developing dementia than those who were not anemic. The link remained after considering other factors, such as age, race, sex and education. Of the 393 people with anemia, 89 people, or 23 percent, developed dementia, compared to 366 of the 2,159 people who did not have anemia, or 17 percent.

“There are several explanations for why anemia may be linked to dementia. For example, anemia may be a marker for poor health in general, or low oxygen levels resulting from anemia may play a role in the connection. Reductions in oxygen to the brain have been shown to reduce memory and thinking abilities and may contribute to damage to neurons,” said Yaffe.