Elderly with anemia have increased risk of dementia

A common health condition among older adults might turn out to be an important modifiable risk factor for dementia, said the senior author of a recent study.

Kristine Yaffe, MD, and colleagues found that seniors with anemia have a 41% higher risk of developing dementia compared with those who don’t have the condition, after adjusting for age, race, sex and education. The findings were posted online July 31 in Neurology.

“We’re very excited about this,” said Dr. Yaffe, professor of psychiatry, neurology and epidemiology at the University of California, San Francisco. She said it’s not known whether correcting the anemia might be helpful in slowing or even stopping the progression of dementia. But that might be a future direction for research, Dr. Yaffe said.

The study didn’t provide information on the types of anemia or dementia that were identified among participants.

When primary care physicians see a patient with suspected or diagnosed cognitive impairment, Dr. Yaffe encourages them to consider assessing the individual for anemia. “Maybe even thinking about improving the anemia might be helpful,” she said.

Possibly contributing to the link between the studied health conditions is that anemia might be a marker for poor overall health, Dr. Yaffe said. Another potential explanation is that low oxygen levels in the brain resulting from anemia could contribute to dementia, she said.

The study findings come as the medical community is preparing for a surge in new cases of dementia, due largely to the nation’s growing elderly population. The Alzheimer’s Assn. estimates that 5.2 million Americans have Alzheimer’s disease, the leading cause of dementia. By 2050, the association predicts that as many as 13.8 million people could have Alzheimer’s.

How data connect the two conditions

For the Neurology study, researchers examined data on 2,552 adults who were free of dementia and between the ages of 70 and 79 when they enrolled in the Health, Aging and Body Composition study in 1997. Participants lived in Memphis, Tenn., or Pittsburgh.

Adults were excluded from the study if they reported difficulties performing mobility-related activities of daily living, walking a quarter mile or climbing 10 steps without resting. During the third year of the study, which was in 1999-2000, blood samples were tested for anemia. The condition was defined as hemoglobin concentrations less than 12 g/dL for women and 13 g/dL for men.

Participants’ cognitive function was assessed periodically during the 11-year study period using the Modified Mini-Mental State examination. Adults were considered to have dementia if it was documented in their hospital records, they were taking medication for the condition or a significant decline was noted on their 3MS cognitive exam.

Researchers found that of the 2,552 participants, 15.4% had anemia at the start of the study. Those individuals were more likely to be older, black, male, with a history of hypertension and less education than adults without anemia, the study said.

During the 11 years of follow-up, 17.8% of participants developed incident dementia. The condition was more common among adults with anemia (22.7% had dementia) compared with seniors who didn’t have anemia (17% developed dementia), data show.

Anemia was more prevalent among black participants than whites and could be associated with the higher burden of dementia in blacks, the study authors said. Additional studies are needed to establish the mechanisms of this association before recommendations are made to prevent dementia either by targeting anemia or improving overall health in seniors, according to the study.