Despite an FDA warning that statins may be associated with cognitive deficits, a review published online Nov. 18 in Annals of Internal Medicine found no definitive evidence of a link between the cholesterol-management drugs and cognitive impairment.

“Published data do not suggest an adverse effect of statins on cognition; however, the strength of available evidence is limited, particularly with regard to high-dose statins,” wrote the authors, led by Karl Richardson, MD, of the Perelman Center for Advanced Medicine in Philadelphia.

The investigators identified 25 studies from literature databases and FDA databases that met their inclusion criteria. The reviewed studies assessed the relationship between statin use and dementia, Alzheimer’s disease, cognitive impairment without dementia or mild cognitive impairment.

From their analysis, they found that low-quality data revealed no relationship between statin use and Alzheimer’s disease or cognitive performance as measured by procedural memory, attention or motor speed. Moderate-quality evidence found no new cases of dementia or mild cognitive impairment or altered cognitive performance as determined by global cognitive performance scores, executive function, declarative memory, processing speed or visuoperception.

A review of FDA databases found few cases of adverse events related to cognitive functioning, a rate similar to the rate reported for other common cardiovascular medications.

The authors noted that their analysis only included three randomized control trials, which resulted in only low-quality or moderate-quality data. Other limitations included inconsistent results and the risk of bias. They also noted that adverse event reporting to the FDA is often inconsistent.

Based on their review, Richardson and colleagues argued that “[l]arger and better-designed studies are needed to draw unequivocal conclusions about the effect of statins on cognition.”