Anemia Linked to Increased Risk of Dementia

Anemia may be linked to an increased risk for dementia in older adults, according to a recent study published in Neurology, the medical journal of the American Academy of Neurology, although researchers aren’t sure of the reasons for the relationship.

Strong Link

The multi-year research project started in 1997 with around 2,500 adult participants in their 70s. They were tested at the beginning for both cognitive functioning and anemia, and regular testing continued for the next ten years. By the end of the study, those who were diagnosed with anemia in the initial testing showed a 41 percent greater chance of developing dementia, even when other factors like sex, race, and education were taken into account.

Dr. David Knopman of the Mayo Clinic, who was handling editor for the study’s publication, warned that the findings don’t mean that anemia itself causes dementia. “The biggest caution in a study like this is over-interpreting it,” he explained. “This study does not, and was not intended to, show a causality between anemia and dementia. All it does is show an association.”

Four Possible Explanations

The study’s authors proposed four possible scenarios that might explain the anemia/dementia link:

  • Chronic brain hypoxia is associated with anemia. That leads to the brain not getting enough oxygen, which might boost the dementia risk. Anemia also has a known association with white matter disease in senior citizens with high blood pressure.
  • Chronic kidney disease can cause anemia and may also play into the dementia link. Animal models show that erythropoietin receptors, which regulate red blood cell production, may have a protective effect on the brain — at least in animal models. Kidney disease lowers erythropoietin levels, possibly lowering that protection.
  • Anemia due to deficiency of micronutrients may tie into cognitive impairment and dementia. Nutrients like iron and vitamin B12 are both essential to proper cognitive functioning. Older adults who are iron deficient may not get enough oxygen in their brains, which may lead to cerebral hypoxia and cognitive issues.
  • Anemia sometimes indicates that a person is in poor health overall. Several studies show a link between dementia and a variety of health conditions that are also associated with anemia.

More Research Needed

Dr. Kristine Yaffe, the study’s author, leans toward oxygen deficiencies as the probable culprit. She told CNN, “I have a feeling it’s probably the oxygen story. It’d be important to find out if you treat anemia, does that reduce your likelihood of developing dementia? Obviously, that’s not ethical, because you’d want to treat everyone. But there’s got to be a back-door way to get at that question.”

Dr. Knopman’s opinion differed; he pointed the finger at poor health. “If I had to vote, I would vote on…a marker of poor health, but I ultimately can’t prove that,” he said. “The one thing that links these non-traditional risk factors may be health behavior. The extent to which people are attentive to their health care, generally, seems like the easiest explanation to me.”

Yaffe plans to do more research, and in the meantime, older adults with anemia should keep a close watch on their overall health, both to potentially ward off dementia and to maintain a better overall quality of life.