A prospective cohort study found stroke survivors who were at least 45 years old had persistent declines in long-term cognitive functioning over a median follow-up period of more than six years. None of the participants had cognitive impairment at baseline.
Lead researcher Deborah A. Levine, MD, of the University of Michigan in Ann Arbor, and colleagues published their findings online in the Journal of the American Medical Association on July 7.
They used statistical modeling to compare the trajectories of cognitive functioning in patients who did and did not have a stroke. Previous research indicated stroke survivors experienced cognitive decline early after stroke, but Levine said it was unclear if the decline continued in the long-term.
“I think patients, their families and their doctors think of stroke as a sudden event that can cause early changes in function, paralysis or speech troubles,” Levine told Cardiovascular Business. “But we don’t usually think of stroke causing new problems years later. That’s what our study suggests, that stroke causes acute problems in cognitive function, but also new problems years later in cognitive function. Patients and their families and doctors need to be aware of these potential changes and take steps to reduce their risk and help the patient improve.”
The researchers evaluated 23,572 participants who enrolled in the REGARDS (Reasons for Geographic and Racial Differencs in Stroke) study between 2003 and 2007. Participants were at least 45 at baseline and were followed every six months through March 31, 2013.
To measure cognitive function, researchers used the Six-Item Screener, Consortium to Establish a Registry for Alzheimer Disease, Word List Learning, Word List Delayed Recall and Animal Fluency Test.
During a median follow-up period of 6.1 years, 515 participants had an incident stroke: 470 ischemic strokes, 43 hemorrhagic strokes and two undetermined strokes. Strokes occurred in 2.1 percent of white participants and 2.3 percent of black participants, which was not a statistically significant difference.
Participants who had a stroke were more likely to be older and male, be current smokers and have less education, diabetes and worse health status than those who did not have a stroke. At baseline, participants who ended up having a stroke had higher levels of systolic blood pressure, waist circumference and depressive symptom scores, as well.
The researchers also found 11.8 percent of people who had a stroke died during the follow-up period compared with 7.9 percent of people who did not have a stroke. The difference was statistically significant.
“Our modeling gives us the average results for an individual with stroke,” Levine said. “Some people do improve and some people steadily get worse, but the beauty of these complex models is they’re able to average all of the effects to say on an individual level that stroke is associated with acute declines in cognitive function and also long-term cognitive decline.”
Guidelines currently recommend patients have their cognitive function assessed when they’re hospitalized for stroke and also in the first few months after stroke. However, they typically are not monitored afterward, although Levine said cognitive therapy and rehabilitation could significantly improve stroke survivors’ cognitive function.
She added that stroke survivors could help prevent another stroke and cognitive decline by controlling vascular risk factors such as high cholesterol, high blood pressure and diabetes, exercising regularly and having a healthy diet.
The researchers are currently examining the risk factors for the acute and long-term declines in cognitive functioning among participants from the REGARDS study. They are interested in determining if the decline is more common based on gender, race and other factors.