An analysis of patients who received warfarin found the presence of atrial fibrillation significantly increased the risk of dementia.

Patients with atrial fibrillation had a significantly higher rate of total dementia, Alzheimer’s disease and vascular dementia compared with patients who had thromboembolism or mechanical heart valves.

Results were presented during a moderated poster session at the Heart Rhythm Society’s scientific sessions in San Francisco on May 5. T. Jared Bunch, MD, of Intermountain Healthcare in Salt Lake City, Utah, was the study’s lead author.

“Our study results are the first to show that there are significant cognitive risk factors for patients treated with warfarin over a long period of time regardless of the indication for anticoagulation,” Bunch said in a news release.

The researchers evaluated 10,537 patients with no history of dementia who received warfarin and were managed by the Intermountain Healthcare Clinical Pharmacist Anticoagulation Service.

Of the patients, 4,460 had atrial fibrillation, 5,868 had thromboembolism and 209 had mechanical heart valves. The researchers noted that patients with atrial fibrillation were older and had higher rates of hypertension, diabetes, heart failure and stroke compared with the other two groups.

After a follow-up period of approximately seven years, the rates of total dementia were 5.8 percent in the atrial fibrillation group and 1.6 percent in the other two groups. The rates of Alzheimer’s disease were 2.8 percent and 0.9 percent, respectively, while the rates of vascular dementia were 1.0 percent and 0.2 percent, respectively.

After conducting a propensity analysis in 6,030 patients to account for baseline demographic differences, the researchers found the long-term risk of total dementia, Alzheimer’s disease and vascular dementia was significantly higher in patients who had atrial fibrillation.

The researchers mentioned in a news release that dementia rates increased in all patients when warfarin levels were consistently too high or too low, although patients with atrial fibrillation consistently had higher rates of dementia. They added that patients who were younger than 70 years old were often at a higher risk of dementia.

“First, as physicians we have to understand that although we need to use anticoagulants for many reasons including to prevent stroke in [atrial fibrillation] patients, at that same time there are risks that need to be considered some of which we are only right now beginning to understand,” Bunch said in a news release. “In this regard, only those that absolutely need blood thinners should be placed on them long-term. Second, other medications like aspirin that may increase the blood thinners effect should be avoided unless there is a specific medical need. Finally, in people that are on warfarin in which the levels are erratic or difficult to control, switching to newer agents that are more predictable may lower risk.”