Statin Use Reduces Risk of Non-Vascular Dementia in Patients with Atrial Fibrillation

Analysis of records from a national insurance database indicates that statin use reduces the danger of cognitive decline associated with atrial fibrillation (AF).

Researchers in Taiwan compared the risk of non-vascular dementia in 51,253 AF patients who used statins and 205,012 AF patients who did not. Each patient in the first group was matched, by both age and sex, to 4 patients in the second. All patients were at least 60 years old.

During the follow-up period, 17,201 patients were diagnosed with non-vascular dementia, but those in the statin group were significantly less likely to develop problems than those in the control group.

The annual incidence of non-vascular dementia was 1.89% in the statin group and 2.20% in the control group (p < 0.001). Subsequent analysis found an adjusted hazard ratio (HR) of 0.832 (95% confidence interval [CR], 0.801—0.864).

The researchers then performed sub-analyses on different types of statin and found that rosuvastatin was associated with the largest risk reduction (adjusted HR = 0.661).

A paper published in the International Journal of Cardiology noted some limitations in these findings — such as the fact that they stemmed from retrospective analysis rather than random trial &mdash; but said the size of the cohort and the strength of the result made the work significant.

“Atrial fibrillation is associated with cognitive decline and may contribute to an increased risk of dementia,” the study authors wrote. “In this large-scale nationwide cohort study, statin use was associated with a lower risk of non-vascular dementia in AF. Use of more potent statin and longer exposure time may be associated with greater benefits.”

The association between AF and dementia was reported 5 years ago, when the Heart Rhythm Journal published the results of a large prospective cohort study. AF patients aged 70 or younger were 2.3 times more likely to develop Alzheimer's disease than comparable controls, even after multivariate adjustment (p=0.001). They also faced an elevated risk of senile dementia (adjusted odds ratio [OR] 3.34, p<.0001), vascular dementia (OR 2.22, p=0.004), and nonspecific dementia (OR 2.87, p<.0001).

Subsequent research from the same group suggested that the elevated risk might stem from the overuse or underuse of anticoagulants.

Among the 2,693 patients whose records were examined in that second study by researchers at Intermountain Medical Center Heart Institute, those who remained in the correct therapeutic range less than 25% of the time developed dementia 4.5 times as frequently as better medicated counterparts.

Patients who kept within the therapeutic range 26% to 50% of the time were 4.1 times more likely to develop dementia. Patients who kept within the therapeutic range 51% to 75% of the time were 2.5 times more likely to develop dementia.

Our results from the study tell us two things,” said principal investigator Jared Bunch, MD, who presented the findings at the 2014 Annual Heart Rhythm Society Scientific Session in San Francisco.

“First, with careful use of anticoagulation medications, the dementia risk can be reduced. Patients on warfarin need very close follow-up in specialized anticoagulation centers if possible to ensure their blood levels are within the recommended levels more often.

“Second, these results also point to a potential new long-term consequence of dependency on long-term anticoagulation medications. In this regard, stroke prevention therapies that do not require long-term anticoagulation medications and reducing the use of these drugs will hopefully lower dementia risk.”

In cases where long-term anticoagulation cannot be avoided, however, physicians may be able to reduce dementia risk not only by keeping patients consistently in the zone but also — if the results of the new study from Taiwan prove accurate &mdash; by considering statins as well.