Stroke Risk Assessment Helps Identify Cognitive Decline Early

Neuroscientists are employing a brain-imaging application and stroke risk assessment to identify signs of cognitive decline early on in individuals who do not yet show symptoms of dementia.

The connection between stroke risk and cognitive decline has been well established by earlier studies. Individuals with increased stroke risk, as gauged by factors such as high blood pressure, have traditionally performed worse on tests of attention, memory, and abstract reasoning.

This small study demonstrated that not only stroke risk, but also the burden of plaques and tangles, as measured by a brain scan, may influence cognitive decline. The imaging tool used in the study was developed at the University of California, Los Angeles (UCLA; USA) and reveals early signs of amyloid beta “plaques” and neurofibrillary tau “tangles” in the brain—the telltale features of Alzheimer’s disease (AD).

The study, published in the April 2013 issue of the Journal of Alzheimer’s Disease, demonstrated that taking both stroke risk and the burden of plaques and tangles into account might provide a more effective assessment of factors determining how people are doing now and will do in the future. “The findings reinforce the importance of managing stroke risk factors to prevent cognitive decline even before clinical symptoms of dementia appear,” said first author Dr. David Merrill, an assistant clinical professor of psychiatry and biobehavioral sciences at the Semel Institute for Neuroscience and Human Behavior at UCLA.

This is one of the first studies to examine both stroke risk and plaque and tangle levels in the brain in relation to cognitive decline before dementia has even set in, according to Dr. Merrill. According to the researchers, the UCLA brain-imaging tool could be beneficial in monitoring cognitive decline over time and offer additional insight when used with other assessment tools.

For the study, the researchers examined 75 individuals who were healthy or had mild cognitive impairment, a risk factor for the future development of AD. The average age of the participants was 63. The individuals underwent neuropsychologic testing and physical evaluations to calculate their stroke risk using the Framingham Stroke Risk Profile, which examines age, gender, smoking status, systolic blood pressure, diabetes, atrial fibrillation (irregular heart rhythm), use of blood pressure medications, and other factors.

Furthermore, each participant was injected with a chemical marker called FDDNP (fluoroethyl)(methyl)amino[-2-naph- thyl](ethylidene) malononitrile), which binds to deposits of amyloid beta plaques and neurofibrillary tau tangles in the brain. The researchers then used positron emission tomography (PET) to image the brains of the study participants—a method that enabled them to pinpoint where these abnormal proteins accumulate.

The findings demonstrated that greater stroke risk was significantly related to lower performance in several cognitive areas, including language, attention, data-processing speed, memory, visual-spatial functioning, problem-solving, and verbal reasoning.

The researchers, furthermore, observed that FDDNP-binding levels in the brain were linked with participants’ cognitive performance. Study participants, for example, who had greater difficulties with language and problem-solving displayed higher levels of the FDDNP marker in their brain regions that control those cognitive activities.

“Our findings demonstrate that the effects of elevated vascular risk, along with evidence of plaques and tangles, is apparent early on, even before vascular damage has occurred or a diagnosis of dementia has been confirmed,” said the study’s senior author, Dr. Gary Small, director of the UCLA Longevity Center and a professor of psychiatry and biobehavioral sciences who holds the Parlow-Solomon Chair on Aging at UCLA’s Semel Institute.

Researchers discovered that several individual factors in the stroke assessment were significant as predictors of decline in cognitive function, including age, systolic blood pressure, and use of blood pressure-related drugs. Dr. Small noted that the next phase of the research would be studies with a larger sample size to validate and expand the findings.

UCLA owns three US patents on the FDDNP chemical marker. Dr. Small and study author Dr. Jorge Barrio are among the inventors.

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