Ask the Expert: Reducing Dementia Risk for Patients on Warfarin
Dr. T. Jared Bunch, a specialist in electrophysiology and cardiology at Intermountain Medical Center Heart Institute in Salt Lake City, Utah, presented new findings in May at the Heart Rhythm Society's 37th Annual Scientific Sessions that addressed the possibility of anticoagulation therapy increasing risk of dementia in patients with atrial fibrillation (AF). His study of more than 10,000 patients with no history of dementia who were treated with warfarin for AF or non-AF conditions showed patients with AF were more likely to suffer a decline in mental ability. However, patients in both groups who spent less time in the therapeutic range were more likely to suffer dementia.
Dr. Bunch recently discussed the association between anticoagulation therapy and dementia, as well as what caregivers need to know about properly managing the blood-thinning medication in order to lessen the risk of cognitive dysfunction.
Your research has linked the over- and under-anticoagulation with warfarin to increased risk of dementia. What are the potential underlying causes of the association? Which patient demographic is at greatest risk?
We’ve hypothesized that dementia is part of a spectrum of cranial injuries with stroke. In the event of stroke, patients have a large cerebral ischemic injury from a large clot or bleed. These events are detected because they are large and cause a clinical deficit. For dementia, we hypothesized that small repetitive events, such as micro-clots or bleeds, injure the brain over time and the accumulative impact results in cognitive decline and dysfunction. Our research group and others have found younger patients — younger than 70 to 80 years — with AF who have been exposed to warfarin for long periods of time are at the highest risk. Our data shows that it’s not only the duration of anticoagulation but, more importantly, the time spent in a safe, effective therapeutic range that impacts dementia risk.
But you also found that AF increases dementia risk even with effective warfarin therapy. Which poses the greater threat: warfarin or AF?
Our most current findings presented at Heart Rhythm 2016examined this question. There was a significantly increased risk of dementia when warfarin levels were consistently erratic in people treated with long-term anticoagulation for AF and non-AF indications. However, when we performed a secondary comparative analysis between the two groups, atrial fibrillation significantly increased risk across all levels of anticoagulation efficacy. So we learned that irregular heart rhythm, and potentially its treatment, contribute to the risk.
Could the use of novel oral anticoagulants solve the issue?
We believe so. We wrote a community-based study that is currently in press with the American Journal of Cardiology that looks at dementia rates in people across Utah who started taking a novel oral anticoagulant. The dementia rates are very low and are statistically lower when compared with an age- and gender-matched population of patients on warfarin. We’ll soon begin a prospective trial to examine this question in a more scientific manner, specifically by comparing warfarin and dabigatran to determine which agent lowers rates of dementia in AF patients.
Do you believe physicians and pharmacists fully understand the neurologic risks associated with warfarin?
Most healthcare professionals are aware of the macro events associated with warfarin such as strokes or intracranial or gastrointestinal bleeding. There’s a lack of studies that look at the smaller events that injure the microvasculature of organs. These events lead to deterioration of function. Newer studies have started to examine this topic and have found associations between warfarin use and kidney dysfunction, incidence of diabetes, and dementia.
What can be done to improve solve the inherent challenges of managing warfarin therapy?
Warfarin is a drug that requires frequent follow-up and education. We’re fortunate here at the Intermountain Medical Center Heart Institute to have a center of warfarin management that’s led by clinical pharmacists who are very motivated to improve the drug’s safety and efficacy. Whenever possible, these specialty centers should be used to manage patients on warfarin. Additionally, home monitoring of international normalized ratio (INR) levels has consistently shown better outcomes than physician monitoring. Finally, apps and wearable technologies may be innovative ways to prompt patients to comply with their medications and provide information to patients and their physicians about current and potential drug-drug, drug-food, and drug-supplement interactions.
- Dan Cook
