Cognitive Decline May Increase Stroke Risk in Older Adults
Studies have previously established that poor cardiovascular health can increase the risk of cognitive impairment, but now researchers say declining memory and cognitive ability in older adults may increase the risk of stroke—and even death. The new findings appear in the journal Stroke.
“Cognitive function and stroke seem to be interrelated, with one impacting the other,” says lead study author Kumar Rajan, PhD, assistant professor of internal medicine at Rush University Medical Center in Chicago, Ill. “Both lower cognitive function and incident stroke significantly increase the risk of mortality independent of each other.”
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Rajan and his colleagues analyzed data on cognitive function in 7,217 adults over age 65 who did not have a history of stroke. They examined the association of baseline cognitive function on stroke risk and changes in cognitive function before and after stroke, while also studying their impact on mortality risk.
The researchers gave participants 4 tests every 3 years to evaluate their cognitive abilities before and after stroke, including short- and long-term memory, attention, awareness, and other mental functions.
Results showed that:
• Patients with lower cognitive test scores before stroke had a 61% higher chance of stroke.
• Stroke, in combination with cognitive decline, increased the risk of death in older adults.
• Cognitive function declined almost twice as fast after stroke.
• Cognitive decline was strongly associated with a higher risk of death, even after controlling for stroke and other health and behavioral risk factors.
• Declining cognitive function before stroke increased the risk of stroke 5-fold in African-Americans compared to European-Americans.
“Cognitive function impacts many aspects of a person’s overall health and well-being, as it can impact management of common risk factors for cardiovascular disease and stroke,” explains study co-author Neelum T. Aggarwal, MD, a neurologist and associate professor in the department of neurological sciences at Rush University Medical Center.
For instance, patients may forget about specific care plans their physicians have recommended to reduce cardiovascular risk factors for heart disease and stroke, or they could be delayed in seeking medical attention because it may take them longer to realize they are having a stroke, she says.
Aggarwal and her colleagues believe that taking a closer look at mental health and cognitive function could help prevent future strokes in older adults.
While primary care physicians typically assess cognition using the mini-mental state examination (MMSE), she says this short test does not adequately assess all areas of cognitive function. To establish a new baseline of cognitive functioning in a patient who has had a stroke, Aggarwal suggests health care providers employ more tests that focus on assessing multiple cognitive functions, including attention, visual-spatial perception, language, and memory.
“Ideally, cognitive function should be assessed in all primary care offices, and especially in those patients with cardiovascular disease or those who have a high risk for stroke,” she says. “Presently, we are working toward finding the optimal tests to use in an outpatient setting that can assist us in our clinical treatment options and monitoring of patients.
In addition, the researchers are also looking at genetic components that may influence the relationship between cognitive function and stroke.
“We are currently examining genetic factors that might increase the risk of pre-stroke and post-stroke cognitive decline,” Rajan says. “We are also examining if the association of cognitive function and incident stroke is similar across these genetic factors.”
—Colleen Mullarkey
Reference
Rajan KB, Aggarwal NT, Wilson RS, Everson-Rose SA, Evans DA. Association of cognitive functioning, incident stroke, and mortality in older adults. Stroke. 7 August 2014. [Epub ahead of print].