January 31, 2014
Anemia, a common condition in the elderly marked by low numbers of red blood cells, may increase the risk of dementia, a new study shows.
“Anemia occurs in up to 23 percent of adults ages 65 and older,” said study author Dr. Kristine Yaffe of the University of California, San Francisco. “The condition has also been linked in studies to an increased risk of early death.”
For the study, researchers looked at 2,552 men and women in their 70s who were part of an ongoing study called the Health, Aging and Body Composition (Health ABC) study. All were free of dementia at the start of the study. They were given memory tests, as well as tests for anemia, over the 11-year study period.
About one in seven, or 393 of the study participants, had anemia at the start of the study. By the end of the study, 445, or about 18 percent of participants, developed Alzheimer’s and other forms of dementia.
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. That means that those with anemia were more than 40 percent more likely to have developed dementia than those who were not anemic.
The researchers considered other risk factors for dementia, including socioeconomic status, memory scores at the start of the study, other medical conditions, signs of inflammation, and the presence of the APOE-E4 gene, which increases Alzheimer’s risk. Still, anemia emerged as an independent risk factor for dementia, they found. The findings appeared in the journal Neurology, from the American Academy of Neurology.
“There are several explanations for why anemia may be linked to dementia,” Dr. Yaffe said. “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.”
Other studies have suggested a link between anemia and a more rapid decline in thinking and memory skills with age, though study results have been mixed. Anemia has also been linked to brain abnormalities in older adults with high blood pressure, and anemia due to kidney disease has also been tied to dementia.
Anemia is sometime caused by deficiencies of vitamin B12, low levels of which have also been linked to Alzheimer’s disease. Anemia is also often caused by low levels of iron, which is critical for transporting oxygen to cells throughout the body, including the brain.
It’s unknown whether prompt treatment of anemia may help to prevent dementia onset. But anemia is often readily treatable, and treatment can relieve symptoms such as fatigue, dizziness and shortness of breath.
Older adults should seek medical attention if they suspect they have anemia, because anemia can be a sign of serious illnesses. You may be able to prevent some types of anemia by eating a heart-healthy and varied diet, something that may also help to keep the brain healthy.
Source: Chang Hyung Hong, MD, PHD, Cherie Falvey, MPH, Tamara B. Harris, MD, et al: “Anemia and Risk of Dementia in Older Adults: Findings from the ABC Health Study.” Neurology, Volume 81, pages 528-533, August 2013.