|An FDDNP brain scan of an individual with mild cognitive impairment (MCI) illustrates the parietal and frontal regions of the brain (see arrows) that have significant relationships to cognitive function. Photo: Courtesy of Dr. David Merrill|
UCLA researchers have used a brain-imaging tool and stroke-risk assessment to identify signs of cognitive decline early on in individuals who don’t yet show symptoms of dementia. The connection between stroke risk and cognitive decline has been well-established by previous research. Individuals with higher stroke risk, as measured by factors like high blood pressure, have traditionally performed worse on tests of memory, attention and abstract reasoning.
The current 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 UCLA and reveals early evidence of amyloid beta “plaques” and neurofibrillary tau “tangles” in the brain – the hallmarks of Alzheimer’s disease.
The study demonstrates that taking both stroke risk and the burden of plaques and tangles into account may offer a more powerful assessment of factors determining how people are doing now and will do in the future, says David Merrill, MD, PhD, assistant clinical professor of psychiatry and biobehavioral sciences at the Jane and Terry Semel Institute for Neuroscience and Human Behavior at UCLA.
This study is one of the first to examine both stroke risk and plaque and tangle levels in the brain in relation to cognitive decline before dementia has even set in, Dr. Merrill says.
According to the researchers, the UCLA brain-imaging tool could prove useful in tracking cognitive decline over time and offer additional insight when used with other assessment tools.
For the study, the team assessed 75 people who were healthy or had mild cognitive impairment, a risk factor for the future development of Alzheimer’s. The average age of the participants was 63.
The individuals underwent neuropsychological testing and physical assessments to calculate their stroke risk using the Framingham Stroke Risk Profile, which examines age, gender, smoking status, systolic blood pressure, diabetes, atrial fibrillation, use of blood pressure medications and other factors.
In addition, each participant was injected with a chemical marker called FDDNP, 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 subjects – a method that enabled them to pinpoint where these abnormal proteins accumulate. The study found that greater stroke risk was significantly related to lower performance in several cognitive areas, including language, attention, information-processing speed, memory, visual-spatial functioning (e.g., ability to read a map), problem-solving and verbal reasoning.
Age-Related Changes in Brain Extracellular Space Affect Processing of Amyloid-beta Peptides in Alzheimer’s Disease,” Journal of Alzheimer’s Disease, April 2013