"Anemia is common in the elderly and occurs in up to 23 percent of adults ages 65 and older," study author Dr. Kristine Yaffe of the University of California, San Francisco, said in a statement. "The condition has also been linked in studies to an increased risk of early death."
For the study, 2,552 older adults ages 70-79 were tested for anemia -- low levels of red blood cells -- and also underwent memory and thinking tests in an 11-year period. Of those, 393 had anemia at the start of the study, but at the end of the study, 445, or 18 percent of participants, developed dementia.
The study, published in the online issue of Neurology, found 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.
"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," Yaffe said. "Reductions in oxygen to the brain have been shown to reduce memory and thinking abilities and might contribute to damage to neurons."
The three main causes of anemia are blood loss due to heavy menstrual periods, trauma, surgery, cancer or bleeding in the digestive or urinary tract; lack of red blood cell production due to genetic factors, poor diet, abnormal hormone levels or chronic diseases, and high rates of red blood cell destruction due to an enlarged or diseased spleen or inherited conditions such as sickle cell anemia, thalassemias and lack of certain enzymes.
Is more steak the answer?
Foods high in iron, include not only red meat but egg yolks; dark, leafy greens such as spinach or collard greens; dried fruit such as prunes or raisins; iron-enriched cereals and grains; oysters, clams, scallops; beans, lentils, chick peas and soybeans; liver and artichokes.