People with atrial fibrillation and Alzheimer’s disease may experience slower cognitive decline when treated with newer NOAC blood thinners, according to research from the Karolinska Institute published in the journal European Heart Magazine.
Atrial fibrillation is a heart rhythm condition common in older adults and also affects many people living with Alzheimer’s disease. Doctors often prescribe blood thinners to these patients to reduce the chance of blood clots and strokes. Previous research has suggested that anticoagulant treatment may reduce the risk of developing dementia, but much less is known about whether these medications influence cognitive decline after Alzheimer’s disease has already been diagnosed.
“There is reason to believe that the treatment could have a positive effect on cognition, for example by improving blood flow and reducing small-scale brain damage,” says Maria Eriksdotter, professor at the Department of Neurobiology, Care Sciences and Society at the Karolinska Institute and senior consultant in geriatric medicine at Karolinska University Hospital, who led the study.
Comparison of newer and older anticoagulants
The researchers analyzed data from the SveDem (Swedish Registry of Cognitive Disorders/Dementia), a national quality registry, and included 7,308 people diagnosed with both atrial fibrillation and Alzheimer’s disease.
Participants were placed into three paired groups. One group received newer anticoagulants known as NOACs, another was treated with the older anticoagulant warfarin (Waran), and the third did not receive any anticoagulant medication.
To track changes in thinking and memory over time, the researchers used the standardized Mini-Mental State Examination (MMSE).
Slower cognitive decline with NOACs
People taking NOACs showed a significantly slower decline in cognitive function than those treated with warfarin or those who did not receive blood-thinning medication.
The difference amounted to just over 0.2 MMSE points per year. While that change is relatively small in a single year, researchers say it could become more significant if it continues over a longer period.
“The difference is modest for an individual patient from one year to the next, but over a longer period even that effect could influence how cognitive function develops. Our findings suggest that NOAC treatment may also be significant for cognition in this group of patients,” says Nanbo Zhu, researcher at the Department of Neurobiology, Caring Sciences and Society at the Karolinska Institutet.
Lower risks of stroke and other complications
The potential benefits were not limited to cognition. Compared with people who did not receive blood thinners, those treated with NOACs also had lower risks of death, stroke, blood clots and fractures.
Warfarin was also associated with lower risks of death, stroke, and blood clots. However, people taking warfarin had a higher risk of serious bleeding.
Why the findings require caution
The researchers highlight that the study has important limitations. Because they were observational, the results cannot prove that NOACs directly caused the slower cognitive decline or other health benefits seen in the data.
Some factors that could affect both the treatment a patient received and how their health changed over time could not be fully evaluated. The researchers also note that some participants may have switched from one medication to another during the follow-up period.
The study was funded, among others, by the Swedish Research Council, the Swedish Brain Foundation, CIMED, ALF project funding and Karolinska Institute funds. Maria Eriksdotter has participated as a consultant in specific meetings with BioArctic AB, Roche, Eli Lilly, Biogen/Eisai and Novo Nordisk, and has given lectures at symposiums sponsored by Roche and BioArctic/Eisai. No other conflicts of interest are reported.