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Original Investigation
May 20, 2019

Association Between Statin Use and Risk of Dementia After a Concussion

Author Affiliations
  • 1Department of Medicine, University of Toronto, Toronto, Ontario, Canada
  • 2Evaluative Clinical Sciences Program, Sunnybrook Research Institute, Toronto, Ontario, Canada
  • 3Institute for Clinical Evaluative Sciences in Ontario, Toronto, Ontario, Canada
  • 4Division of General Internal Medicine, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
  • 5Center for Leading Injury Prevention Practice Education & Research, Toronto, Ontario, Canada
JAMA Neurol. Published online May 20, 2019. doi:10.1001/jamaneurol.2019.1148
Key Points

Question  Is statin use associated with an increased or decreased risk of subsequent dementia after a concussion?

Findings  In this large extended population-based double cohort study following 28 815 patients after a concussion, the 5-year incidence of dementia was substantial and statin use was associated with a significantly reduced risk of subsequent dementia.

Meaning  Concussions are associated with an increased long-term risk of dementia, which is modestly reduced for patients receiving a statin.

Abstract

Importance  Concussions are an acute injury that may lead to chronic disability, while statin use might improve neurologic recovery.

Objective  To test whether statin use is associated with an increased or decreased risk of subsequent dementia after a concussion.

Design, Setting, and Participants  Large extended population-based double cohort study in Ontario, Canada, from April 1, 1993, to April 1, 2013 (enrollment), and continued until March 31, 2016 (follow-up). Dates of analysis were April 28, 2014, through March 21, 2019. Participants were older adults diagnosed as having a concussion, excluding severe cases resulting in hospitalization, individuals with a prior diagnosis of dementia or delirium, and those who died within 90 days.

Exposure  Statin prescription within 90 days after a concussion.

Main Outcome and Measure  Long-term incidence of dementia.

Results  This study identified 28 815 patients diagnosed as having a concussion (median age, 76 years; 61.3% female), of whom 7058 (24.5%) received a statin, and 21 757 (75.5%) did not receive a statin. A total of 4727 patients subsequently developed dementia over a mean follow-up of 3.9 years, equal to an incidence of 1 case per 6 patients. Patients who received a statin had a 13% reduced risk of dementia compared with patients who did not receive a statin (relative risk, 0.87; 95% CI, 0.81-0.93; P < .001). The decreased risk of dementia associated with statin use applied to diverse patient groups, remained independent of other cardiovascular medication use, intensified over time, was distinct from the risk of subsequent depression, and was not observed in patients after an ankle sprain.

Conclusions and Relevance  In this study, older adults had a substantial long-term risk of dementia after a concussion, which was associated with a modest reduction among patients receiving a statin.

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