Stroke is associated with cognitive decline in the weeks immediately following the event, but a new study shows that the impact of stroke could be more far-reaching than this. Researchers have found that many patients experience accelerated and persistent cognitive decline over the 6 years following a stroke.

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Strokes occur when the blood supply to the brain is disrupted, either by a blockage or the rupture of a blood vessel.

The study, published in JAMA, tracked the cognitive changes in survivors of incident stroke, following the participants up for an average of 6.1 years.

“We have known that stroke is associated with cognitive decline over the short term,” says study author Dr. Deborah Levine, of the University of Michigan Medical School and Ann Arbor VA Health System. “We did not know whether stroke is associated with declines in thinking speed and memory over the years after the event.”

Around 795,000 people in the US experience a stroke every year. In 2010, around 7 million adults were stroke survivors, according to the authors of the study.

“Disability due to stroke is a major driver of health burden and costs for families, health care systems, and public programs such as Medicare and Medicaid,” they explain. “Cognitive impairment after stroke is a major contributor to this disability, and its prevalence has increased sharply in older adults.”

Despite the societal impact that stroke-related cognitive decline has, the authors reveal it is currently unclear whether stroke survivors experience a quicker rate of cognitive decline following the event compared with the rate of cognitive decline beforehand.

For the study, the researchers conducted a prospective analysis of 23,572 people without any cognitive impairment from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study. Participants were aged 45 years or older, and from 2003-07 until March 2013 the researchers tracked how their cognitive functioning changed over time.

During the study period, a total of 515 participants survived a stroke, with 23,057 participants unaffected by stroke entirely. The researchers found that those who survived incident stroke experienced significantly faster rates of cognitive impairment after their strokes compared with before.

Overall, stroke was associated with accelerated and persistent declines in cognitive and executive function. Significant acute declines in new learning and verbal memory were also associated with stroke, although no acceleration from the pre-stroke rates of change for these was observed.

The researchers believe their findings could have implications for clinical practice, research and health care policies, suggesting that stroke survivors should be monitored over the years after the event and not just before hospital discharge and at immediate follow-up appointments:

Given that poststroke cognitive impairment increases mortality, morbidity, and health care costs, health systems and payers will need to develop cost-effective systems of care that will best manage the long-term needs and cognitive problems of this increasing and vulnerable stroke survivor population.”

“We need to determine whether the acute and also the long-term accelerated cognitive declines after stroke are the result of incomplete rehabilitation from the initial stroke, ongoing or new brain injury from uncontrolled vascular risk factors, behavior changes or other mechanisms,” Dr. Levine concludes.

In an accompanying editorial, Dr. Philip B. Gorelick and David Nyenhuis, PhD, of the Michigan State University College of Human Medicine in Grand Rapids, write that information obtained from cognitive screening can be used to plan the daily management of patient care “based on cognitive performance and need for possible neuropsychological testing.”

“In addition,” they add, “intensification of vascular risk management may be indicated for patients at risk of cognitive impairment in an attempt to prevent subsequent stroke, myocardial infarction, loss of cognitive vitality, and overall disability.”

Previously, Medical News Today reported on a study finding that strokes result in a loss of cognitive function equivalent to the brain aging by an average of 8 years.