- A study has found that blood thinners called NOACs may slow cognitive decline in those with Alzheimer’s.
- Alzheimer’s patients with AFib are prone to brain damage from “silent strokes.”
- However, blood thinners can help prevent the formation of the clots that cause these strokes.
- Experts say NOACs are safer and more predictable than warfarin, a common blood thinner.
- The findings have implications for improving treatment for those with Alzheimer’s by making it safer to prescribe blood thinners.
A nationwide Swedish study sheds light on how blood thinners might help slow cognitive decline in people with both atrial fibrillation (AFib), an irregular heart rhythm, and Alzheimer’s disease.
The researchers specifically examined newer blood thinners called non-vitamin K antagonist oral anticoagulants (NOACs).
The study, published August 12 in the European Heart Journal, suggests that these newer blood thinners may not only protect against strokes but also support brain health.
NOAC blood thinners may offer greater cognitive benefits than older medications such as warfarin or no anticoagulant treatment.
“There are reasons to believe that the treatment could have a positive effect on cognition, for example by improving blood flow and reducing small-scale damage in the brain,” lead study co-author Maria Eriksdotter, professor at the Department of Neurobiology, Care Sciences and Society at the Karolinska Institutet, and senior consultant in geriatric medicine at Karolinska University Hospital in Stockholm, Sweden, said in a news release.
The researchers used data from several linked national Swedish registries to study over 7,300 individuals diagnosed with Alzheimer’s disease who also had AFib before their dementia diagnosis.
These registries included detailed information on dementia diagnoses, cognitive test scores, hospital visits, prescription medications, and deaths.
The key measure of cognitive function was the Mini-Mental State Examination (MMSE), a widely used test that assesses memory, attention, and other cognitive skills.
The study looked at patients’ use of blood thinners around the time they were diagnosed with Alzheimer’s.
People were grouped into three categories:
- those not taking blood thinners
- those taking warfarin (an older blood thinner)
- those taking NOACs (newer blood thinners)
The researchers followed these individuals for up to 5 years, tracking changes in their cognitive test scores and recording important health events like strokes, major bleeding, fractures, and death.
To make fair comparisons, the team used statistical methods to balance differences between the groups, such as age, other health conditions, and medication use.
This approach helps account for differences between the groups that could otherwise influence the results.
The study found that people taking NOACs experienced a slower decline in cognitive function compared to those on warfarin or those not taking any blood thinner.
While warfarin users did not show a significant difference in memory loss compared to non-users, NOAC users showed a modest but meaningful slowing in the rate of decline.
According to the researchers, this suggests that NOACs might have an added benefit beyond stroke prevention in patients with both heart rhythm problems and Alzheimer’s disease.
In addition to cognitive benefits, NOAC users had lower risks of stroke, death, and fractures compared to those not on blood thinners.
Further, NOACs did not increase the risk of major bleeding, a common concern with blood thinners.
Warfarin users also had fewer strokes and deaths than non-users but faced a higher risk of serious bleeding.
When directly comparing NOACs to warfarin, NOACs were associated with fewer strokes and less major bleeding, which aligns with previous research in the general population.
This is especially relevant for patients with Alzheimer’s, who have been underrepresented in clinical studies.
The researchers also noted that managing warfarin can be challenging, especially for people with cognitive impairment, which may affect adherence to treatment.
The newer NOACs are generally easier to use, which could partly explain their better outcomes.
Overall, the findings suggest that NOACs may offer advantages over warfarin for patients with atrial fibrillation and Alzheimer’s disease, including a potential benefit in slowing cognitive decline.
“Our findings suggest that NOAC treatment may also be significant for cognition in this patient group,” lead study co-author Nanbo Zhu, researcher at the Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, said in a news release.
Bhaskar Semitha, MD, a cardiothoracic surgeon with ClinicSpots, said that to understand why blood thinners help Alzheimer’s patients, it’s important to look at the consequences of AFib. Semitha wasn’t involved in the study.
“In AFib, the upper chambers of the heart quiver instead of beating effectively, allowing blood to pool and form microscopic clots,” he told Healthline. “These micro-emboli are constantly pumped into the brain, causing ‘silent strokes.’”
This leads to continuous damage of the smaller blood vessels of the brain, depriving the brain tissue of oxygen, and speeding up cognitive decline.
However, the use of NOACs “changes the equation,” Semitha said.
First of all, they are more predictable and safe for Alzheimer’s patients compared to warfarin.
“[M]emory issues led to missed or doubled doses, and the drug required strict dietary limitations and constant blood monitoring,” he said. “Warfarin also carries a relatively high risk of intracranial hemorrhage.”
On the other hand, NOACs have highly predictable pharmacokinetics, require no routine blood monitoring, and have a lower risk of spontaneous brain bleeding.
“By safely neutralizing the micro-clots caused by AFib, NOACs protect the remaining healthy brain tissue from ischemic damage without introducing the severe bleeding risks of older drugs,” said Semitha.
This will alter the risk-benefit analysis that physicians perform when treating elderly patients, he added.
Currently, doctors hesitate to prescribe blood thinners because of the danger that patients will fall and suffer from a brain bleed.
However, the ability of NOACs to preserve cognitive function and slow dementia progression will now outweigh this fear.
Additionally, Semitha said there will be a shift to dual-purpose prescribing.
“Cardiologists and neurologists will increasingly view NOACs not just as a stroke-prevention tool for the heart, but as an active, disease-modifying, neuroprotective therapy for the brain,” he said.
“It will encourage far closer collaboration between cardiovascular and neurological care teams.”
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