What’s The Connection: Heart Disease Risk Factors & Brain Function
More and more research is finding that physical illnesses can affect many more body functions than those directly involved with them. This negative interaction has profound effects not only on physical health, but also on quality of life. According to a multicenter study led by University of California scientists, we’re learning that older adults with stroke risk have significantly increased risk for some types of cognitive decline.
The study involved 73 older women and men who had not had a stroke and did not have dementia. Results showed that participants had substantially greater risk for decline in some aspects of “executive function”—specifically in verbal fluency and the ability to ignore irrelevant information. Executive function includes the ability to engage in goal-directed behavior, such as remaining attentive, multitasking, thinking flexibly, inhibiting attention to irrelevant sensory information and generating ideas.
Elevated risk factors for coronary artery disease have already been linked to a decline in cognitive function in older adults without dementia. However, few studies have examined specific aspects of neuropsychological functioning in people with a wide range of risk for coronary artery disease and stroke. The goal of this study was to see if the risk for these conditions was associated with declines in specific neuropsychological functions.
"Being at risk for a stroke puts you at risk for some types of cognitive decline. Treating stroke risk factors has the potential to decrease a decline in executive function in otherwise healthy people".
The study involved women and men with a mean age of 78 who live independently. They were recruited as part of the ongoing “Aging Brain: Vasculature, Ischemia and Behavior” study involving researchers at UCSF, University of Southern California and University of California, Davis.
The researchers assessed the participants’ risk for coronary artery disease using the widely used Framingham Coronary Risk Score, which incorporates coronary artery disease risk factors of age, cholesterol levels, blood pressure, diabetes and smoking, to generate an individual’s risk of stroke within 10 years.
Participants underwent testing for executive function and memory through a series of neuropsychological tests. Those at a higher risk for stroke performed worse on verbal fluency, a test designed to measure the ability to quickly generate verbal information. It also showed that higher risk for stroke, as well as age, accounted for a significant portion of decline in the ability to ignore irrelevant information.
“The findings reveal that if you control for age, education and gender, participants with higher risk for stroke perform significantly more poorly in verbal fluency and in inhibition, even when controlling for a history of stroke and dementia,” said the lead author of the study, Jonathan Gooblar, a research associate in the UCSF Memory and Aging Center.
At the same time, the research “suggests that treating stroke risk factors potentially could decrease decline in executive function in otherwise healthy patients,” said the senior author of the study, Joel H. Kramer, PsyD, UCSF clinical professor of neuropsychology and the director of the neuropsychology program at the UCSF Memory and Aging Center.
The study also evaluated the participants in a different way, by dividing them into high and low risk groups according to a cutoff widely used (15 percent risk of stroke in 10 years for women and 20 percent for men). “We showed that this common method of dividing up populations didn't detect cognitive impairment as well as treating risk as a continuous factor,” said Gooblar. “Even people with a ‘lower' risk score according to that dichotomy (12 percent for example) were more likely to have cognitive impairment than lower risk scores.”
Kramer said he suspects that coronary risk factors cause cerebrovascular damage that will be detected in neuroimaging scans and will correlate with cognitive decline. (The team conducted scans, but has not yet analyzed the data.) Looking ahead, he said, the team plans to focus on participants who have elevated heart risk factors, in order to identify the mechanisms of cognitive change. "Within that group, there probably will be some who have early Alzheimer’s disease and some who don’t. We want to understand the relationship between vascular risk factors and Alzheimer’s disease, as well as the relationship between vascular risk factors and cognitive change that’s purely associated with vascular changes in the brain resulting from heart disease risk factors."
The principle investigator of the NIH-funded study is Helena Chiu, MD, of USC. Other co-authors of the study are Wendy J. Mack, PhD, of USC, and Charles DeCarli, MD, Dan Mungas, PhD and Bruce R. Reed, PhD, of UC Davis