, compared with similar adults not taking statins.
The findings come from a population-based double cohort study of 28,815 patients in the Ontario Health Insurance Plan. Study patients were enrolled over 20 years, and had a minimum follow-up of 3 years. The study excluded patients hospitalized caused by a severe concussion, those previously diagnosed with delirium or dementia, and those who died within 90 days of their concussions.
Concussions are a common injury in older adults and dementia may be a frequent outcome years afterward, Donald A. Redelmeier, MD, of the University of Toronto and colleagues wrote in a study published in JAMA Neurology. A concussion should not be interpreted as a reason to stop statins, and a potential neuroprotective benefit may encourage medication adherence among patients who are already prescribed a statin.
Of the 28,815 patients studied, 4,727 patients (1 case per 6 patients) developed dementia over the mean follow-up period of 3.9 years. The 7,058 patients who received a statin had a 13% reduced risk of developing dementia, compared with the 21,757 patients who did not (relative risk, 0.87; 95% confidence interval, 0.81-0.93; P less than .001).
Even though statin use was associated with a lower risk, the subsequent incidence of dementia was still twice the population norm in statin users who had concussions, the researchers wrote. The findings indicate concussions are a common injury in older adults and dementia may be a frequent outcome years after concussions.
Statin users who had concussions continued to have a reduced risk of developing dementia after adjustment for patient characteristics, use of other cardiovascular medications, dosage, and depression risk. The statin associated with the greatest risk reduction was rosuvastatin; simvastatin was associated with the least risk reduction. With the possible exception of angiotensin II receptor blockers, no other cardiovascular or noncardiovascular medications were associated with a decreased risk of dementia after a concussion, the researchers wrote.
They also examined data for elderly patients using statins after an ankle sprain and found the risk of dementia was similar for those who did and did not receive statins after the injury.
Factors such as smoking status, exercise, drug adherence, and other unknown aspects of patient health might have influenced the results of the study, the researchers acknowledged. Additionally, a secondary analysis was not statistically powered to distinguish the relative efficacy of statin use before a concussion.
This study was funded in part by a Canada Research Chair in Medical Decision Sciences, the Canadian Institutes of Health Research, the BrightFocus Foundation, and the Comprehensive Research Experience for Medical Students at the University of Toronto. The authors reported no relevant conflicts of interest.
SOURCE: Redelmeier DA et al. JAMA Neurol. 2019 May 20. doi: 10.1001/jamaneurol.2019.1148.