A newer generation of blood-thinning medicines may do more than prevent strokes in people who have both atrial fibrillation and Alzheimer’s disease.
A large Swedish study suggests that patients taking these drugs experienced a slightly slower decline in thinking and memory over time.
Atrial fibrillation is a common condition in which the heart beats irregularly and sometimes very quickly. It becomes more common with age and can allow blood to pool inside the heart, increasing the chance that a clot will form.
If a clot travels to the brain, it can block a blood vessel and cause a stroke. Doctors therefore often prescribe anticoagulants, commonly called blood thinners, to people with atrial fibrillation who have a significant risk of stroke.
Older anticoagulants such as warfarin have been used for decades. Newer medicines, often called NOACs or direct oral anticoagulants, are now widely used because they generally require less routine blood testing and have more predictable effects.
Researchers have previously found links between atrial fibrillation and dementia. Large strokes can clearly damage the brain, but scientists also suspect that tiny clots, small areas of blood vessel damage and changes in blood flow may gradually affect thinking even when no major stroke is diagnosed.
This raised an important question for people who already have Alzheimer’s disease. Could preventing clots with anticoagulant medicines also influence how quickly their memory and thinking abilities decline?
Researchers at Karolinska Institutet in Sweden examined information from the Swedish Register for Cognitive Disorders/Dementia, known as SveDem. Their study included 7,308 people who had been diagnosed with both Alzheimer’s disease and atrial fibrillation.
The researchers created three matched groups. One group received newer NOAC medicines, another was treated with warfarin, and a third group was not using an anticoagulant.
To follow cognitive changes, the researchers used scores from the Mini-Mental State Examination, or MMSE. This widely used test asks questions and gives simple tasks that assess abilities such as memory, attention, orientation and language.
People taking NOACs showed a slower decline in MMSE scores than those taking warfarin or no anticoagulant. The difference was a little more than 0.2 points per year.
That is a small difference for one person over a single year. However, the researchers noted that if the effect continues over several years, even a modest slowing could influence how long some patients maintain certain thinking abilities.
There are several possible explanations. Preventing small clots and strokes may protect brain tissue, while improved circulation could potentially reduce some of the additional blood vessel damage that occurs alongside Alzheimer’s disease.
The researchers also examined other health outcomes. Compared with people who received no anticoagulant, those taking NOACs had lower risks of death, stroke, blood clots and fractures.
Warfarin was also associated with lower risks of death, stroke and blood clots compared with no anticoagulant treatment. However, people treated with warfarin had a higher risk of major bleeding, an important concern because anticoagulants reduce the blood’s ability to clot.
The study was led by Professor Maria Eriksdotter and included researcher Nanbo Zhu and colleagues at Karolinska Institutet. It was published in the European Heart Journal.
The findings are important because atrial fibrillation and Alzheimer’s disease frequently occur together in older adults. Treatment decisions in these patients can be complicated because doctors must balance protection from stroke against the possibility of serious bleeding.
However, the study does not prove that NOACs directly slow Alzheimer’s disease. It was observational, meaning researchers examined what happened to patients receiving different treatments rather than randomly assigning the medicines.
People prescribed NOACs may have differed from those receiving warfarin or no anticoagulant in ways that affected their outcomes. The researchers tried to make the groups comparable, but unknown differences could still have influenced the results.
Medication use may also have changed during follow-up, and the MMSE captures only part of a person’s cognitive health. A difference in test scores does not automatically mean the same difference in independence, daily functioning or quality of life.
Even with these limitations, the study raises an intriguing possibility. For people who already need anticoagulation because of atrial fibrillation, choosing a modern NOAC may potentially provide brain-related advantages as well as protection against stroke, but randomized research would be needed to confirm that benefit.
If you care about brain health, please read studies about low choline intake linked to higher dementia risk, and how eating nuts can affect your cognitive ability.
For more health information, please see recent studies that blueberry supplements may prevent cognitive decline, and results showing higher magnesium intake could help benefit brain health.
Source: Karolinska Institutet.
