Researchers have developed a new measure of brain health—dubbed the cognitive clock—which may offer a novel approach to identifying individuals at risk of memory and thinking problems, according to a study published in Alzheimer's & Dementia: The Journal of the Alzheimer's Association. The tool measures brain health based on cognitive performance and may be used in the future to predict the likelihood that an individual will develop memory and thinking problems as they age.
Believing that cognitive performance data could be used to distinguish between normal cognitive aging and the potential development of age-related memory and thinking problems, the investigators examined data acquired from several long-term studies. These included the Rush Memory and Aging Project (MAP), which included people living in the community in the greater Chicago, Illinois area; the Religious Orders Study (ROS), which included older Catholic clergy from across the United States; and the Chicago Health and Aging Project (CHAP), a biracial population-based study.
“We used long-term cognitive testing data from our participants to develop a profile of cognitive aging, what we call the cognitive clock,” said Patricia Boyle, PhD, professor in Rush Medical College's Division of Behavioral Sciences, in a press release. “The cognitive clock reflects the general pattern of age-related cognitive decline and allows us to see who is doing better than average and who is doing worse at a given point in time. This helps us identify who might be at high risk of developing memory and thinking problems.”
The researchers used data from 1057 participants from the MAP and the ROS, who began without cognitive impairment and underwent yearly cognitive assessments for up to 24 years. These assessments included the Mini-Mental State Exam, a widely used test of cognitive function among the elderly that measures orientation, attention, memory, language, and visual-spatial skills. This data was then used to identify the typical profile of cognitive aging using a novel statistical approach, charting how cognitive performance changes over time with advancing age.
“We found that, on average, cognition remains stable until a cognitive age of around 80 years of age, then declines moderately until 90, then declines more rapidly until death,” Boyle said in the release. “Further, we found that cognitive age is a much better predictor than chronological age of dementia, mild cognitive impairment and mortality. It also is more strongly associated with other aspects of brain health.”
This cognitive clock was then applied to an independent sample of 2592 participants from CHAP to confirm its accuracy for predicting outcomes such as Alzheimer dementia, mild cognitive impairment, and mortality. The results of the study suggested that cognitive age was a better predictor of these outcomes than chronological age. According to the study authors, this tool could potentially serve as an aid in aging research moving forward and may offer a new diagnostic to identify at risk individuals.
“It is very difficult to develop a test or biomarker that accurately predicts health outcomes on an individual level,” Boyle said in the press release. “This has been a longstanding challenge in aging research. However, we are hoping that with additional research and validation, we may be able extend the approach applied here to clinical settings. Ideally, we could have a patient come into a clinic or hospital and complete a brief cognitive screen that gives us information to plug into a formula to estimate their cognitive age. That will provide important information about their brain health, and from there, we can estimate likelihood of developing [Alzheimer] disease or dementia in the coming years.”
Rush researchers develop new measure of brain health [news release]. EurekAlert; June 1, 2021. Accessed June 1, 2021. https://www.eurekalert.org/pub_releases/2021-06/rumc-rrd052821.php