There is no single test to determine if a person has dementia. The harsh reality is that at this point it can only be conclusively diagnosed during an autopsy.
So, for now, doctors rely on physical exams, lab work, and cognitive indicators to diagnose dementia with a high degree of certainty while a patient is still alive.
Anemia can be a sign that someone has an increased risk of developing dementia, according to a new study published in Neurology, the medical journal of the American Academy of Neurology.
“I’ve been studying Alzheimer’s for a long time,” says study author Dr. Kristine Yaffe of the University of California, San Francisco. “In particular, I’m interested in the things you can change: cardiovascular disease, sleep, physical activity. We have done a number of studies on how different chronic diseases in the body affect aging. We started to delve into the issue of anemia … after seeing rudimentary studies that linked it to dementia.
Anemia is a condition in which your red blood cells do not carry enough oxygen to the rest of your body. In most cases, a lack of iron causes anemia.
Anemia can lead to extreme fatigue. Blood loss is the most common cause, leading to short- or long-term symptoms, which can range from mild to severe.
“Anemia is common in the elderly and affects up to 23% of adults aged 65 and over,” says Yaffe. “The condition has also been linked in studies to an increased risk of premature death.”
The study followed approximately 2,500 participants who were in their 70s when data collection began in 1997. They were first tested for anemia and cognitive function, and underwent subsequent testing over the course of. the following decade.
The researchers found that people who had anemia at the start of the study had a 41% higher risk of developing dementia than those who were not anemic. The link remained after taking other factors into account, such as age, race, gender, and education.
“There are several explanations as to why anemia may be linked to dementia,” says Yaffe. “For example, anemia may be a marker of poor health in general, or low oxygen levels resulting from anemia may play a role in the connection. Reducing oxygen in the brain has been shown to reduce memory and thinking skills and can help damage neurons. “
“The biggest caveat in a study like this is to overinterpret it,” says Dr. David Knopman, neurology consultant at the Mayo Clinic (who served as editor for the publication of this study). “This study does not – and was not intended to – show causation between anemia and dementia. All it does is show association.
The study authors concede that “the mechanisms linking anemia to … dementia are not clearly understood”, but discussed four hypotheses that had been previously proposed:
1. Chronic cerebral hypoxia (lack of oxygen) associated with anemia may contribute to the risk of dementia. Anemia has been associated with the progression of white matter disease in the elderly with hypertension.
2. Anemia due to chronic kidney disease may be linked to dementia. Erythropoietin receptors, which regulate the production of red blood cells, appear to have a protective effect on the brain – at least in animal models. Kidney disease or failure is known to lower erythropoietin levels.
3. Anemia due to micronutrient deficiency – such as iron and vitamin B12 – can also be associated with cognitive impairment and dementia. Iron deficiency, because it plays an important role in the transport and storage of oxygen in the brain, can lead to cerebral hypoxia and cognitive decline.
4. It is also possible that anemia is a marker of poor health. Other studies have shown that dementia is often associated with a range of health outcomes, or that another latent variable associated with both anemia and dementia is behind the association .
“If I had to vote, I would vote on the fourth: a marker of ill health,” Knopman says, “but ultimately I can’t prove it. The only thing that links these non-traditional risk factors may be health behavior. The extent to which people pay attention to their health care, in general, seems to me to be the simplest explanation.
Next, Yaffe hopes to study the underlying mechanism connecting anemia and dementia.
“I have a feeling this is probably the story of oxygen (the lack of oxygen in the brain),” she says. “It would be important to know if you are treating anemia, does that reduce your risk of developing dementia? Obviously this is not ethical because you would want to treat everyone. But there must be a back door way to answer this question.