July 15, 2015

Stroke accelerates cognitive decline over time, study finds

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ct scan3Stroke has fallen to the fifth-leading cause of death in the United States due to decreases in people dying from it, and this increase in survivors has led to questions about their health in the years following stroke.

In the United States, about 795,000 residents experience a stroke yearly, according to the American Heart Association. Over the last two decades, while accounting for age, disability rates due to stroke increased by 40 percent, according to the State of U.S. Health report.

A new Journal of the American Medical Association study looked at 23,572 Reasons for Geographic and Racial Differences in Stroke (REGARDS) study participants age 45 years or older without cognitive impairment, which includes failing memory and processing thoughts more slowly. The research team, which included investigators from the University of Alabama at Birmingham, report those who experienced a stroke had an acute decline in cognitive function and also accelerated and persistent cognitive decline over six years.

“Many stroke survivors are monitored for physical and cognitive effects only during the acute rehabilitation period during which the bulk of progress is expected to occur,” said senior study author Virginia Wadley, Ph.D., associate professor in the UAB Division of Gerontology, Geriatrics and Palliative Care. “Whether survivors are at risk for greater or more rapid cognitive decline over subsequent years has been difficult to answer, because there seldom have been pre-stroke cognitive data available for comparison.”

Over the median follow-up of 6.1 years, 515 participants survived incident stroke and 23,057 remained stroke-free.

“We looked at all REGARDS participants’ rates of cognitive change, including those who have and have not gone on to have a stroke, to detect the impact of stroke on cognition,” Wadley said. “Because we could utilize this data set, we were able to find that stroke survivors are vulnerable to a faster rate of decline in various thinking skills in the years following stroke compared to age/disease-related changes in the years prior to stroke and to changes that occur in peers who have not experienced stroke.”

Wadley says this finding has important implications for clinical practice, research and potentially health policy.

“Our findings highlight a need for long-term monitoring and follow-up care for stroke survivors, with a focus on the mounting potential for cognitive impairment in subsequent years,” Wadley said. “Therapies to support cognitive abilities should be a high priority. And long-term cognitive abilities could be an important domain to evaluate in relation to initial stroke treatments.”

This study was supported by the National Institute of Neurological Disorders and Stroke of the National Institutes of Health and REGARDS principal investigators Drs. George and Virginia Howard, both professors in the UAB School of Public Health.

“The Howards’ generous collaborative spirit and enthusiasm for discovery outside the clinic-based paradigms are the reasons for the scope of knowledge being created in this ongoing research,” Wadley said. “We also are indebted to our gracious study participants who are helping us better understand risks for stroke and cognitive decline; knowledge that ultimately will contribute to reducing these adverse outcomes.”