With an aging population, more people are relying on heart drugs like Warfarin to prevent blood clots. However, a new study has suggested that when these patients also have atrial fibrillation, their chance of getting dementia rises.
The study comes from Dr. T. Jared Bunch and other researchers from the Intermountain Medical Center Heart Institute in Salt Lake City, Utah. Dr. Bunch presented the results May 5th at the 37th Annual Heart Rhythm Society Scientific Sessions.
For their study, the researchers recruited 10,537 patients, aged 18 and older, who had no history of dementia before the study started. These patients had either atrial fibrillation, which is an abnormal heart rhythm, or other heart conditions like valvular heart disease, which is a defect in one of the heart valves, or thromboembolism, which is when a blood clot is dislodged and blocks a blood vessel. These patients were all being treated with the blood-thinning drug, Warfarin, a common heart medication.
The researchers followed up with these patients for about seven years, seeing how their Warfarin treatments were progressing and if they had developed symptoms of dementia. When the researchers crunched the numbers, they found that the patients taking Warfarin for atrial fibrillation were more likely than the patients taking Warfarin for other conditions to develop all types of dementia.
However, in both the atrial fibrillation and non-atrial fibrillation patients, the risk of dementia increased when the Warfarin treatments were not managed properly. This was when the time in therapeutic range, which is essentially the frequency of doctor visits, either decreased or became more erratic and when the Warfarin levels were regularly either too high or too low. This suggests that not properly monitoring patients who are taking Warfarin and not making sure they take the correct dose can increase the risk of dementia.
The study authors suggest these findings should make doctors more cautious about prescribing blood thinners like Warfarin. These blood thinners are needed to help lower the risk of blood clots that can lead to heart attack and stroke, but the researchers suggest that doctors should be careful about who they place on Warfarin long-term. As well, patients who have erratic levels of the drug may be better off on other drugs. The researchers also suggest that doctors should be careful about prescribing drugs like Aspirin which can increase the effects of blood thinners.
Although the researchers seem to have proven a link between taking Warfarin and an increased risk of dementia, they are not sure what causes the increased risk. More studies would be needed to determine how the combination of atrial fibrillation and Warfarin contribute to dementia risk.
Originally introduced as a pesticide in 1948, because of its ability to make mice and rats bleed to death in high doses, in 1954 doctors began officially using Warfarin to treat heart patients. Although there are alternative drugs, Warfarin is still the most-prescribed oral anticoagulant in North America. Warfarin is a blood thinner that works by reducing the clotting proteins in blood to help prevent the blood from clotting as much. If blood clots form, they can clog blood flow in areas such as the heart or brain, starving these organs of oxygen and causing a heart attack or stroke.
Although Warfarin is a common drug, it does have its risks. Warfarin can help prevent the blood from getting too thick, but it can also cause the blood to become too thin, increasing the risk of bleeding. Doctors must carefully manage dosages of the drug so their patients do not take too much or too little, putting them at risk for either blood loss or blood clots. Physicians monitor Warfarin dosage by regularly testing blood to see how well it coagulates.