The ability to detect dementia at an early stage in high-risk older adults can allow time for modifying lifestyle risk factors and early therapeutic interventions that could potentially delay or prevent the clinical onset of Alzheimer’s disease. Research on non-invasive and sensitive neuromarker signatures for mild cognitive decline is therefore of great interest.
In an article titled “Memory-Related Frontal Brainwaves Predict Transition to Mild Cognitive Impairment in Healthy Older Individuals Five Years Before Diagnosis“published in the Journal of Alzheimer’s Disease, an international team of collaborating researchers demonstrate a new way to predict the risk for amnestic mild cognitive impairment (aMCI), years before a clinical diagnosis.
This study shows direct measures of brain EEG (electroencephalography) signatures while an individual is engaged in mental activity are more sensitive and accurate predictors of memory decline than current standard behavioral testing.
“Many studies have measured electrophysiological rhythms during resting and sleep to predict Alzheimer’s risk. This study demonstrates that better predictions of a person’s cognitive risk can be made when the brain is challenged with a task,” says Yang Jiang, PhD, associate professor of behavioral sciences, an affiliated faculty member at the Sanders-Brown Center on Aging and lead investigator on the study.
“Additionally, we learned that out of thousands of possible brain oscillation measures, left-frontal brainwaves during so-called working memory tasks are good predictors for dementia risk,” says Jiang.
It has already been reported that brain waves associated with daily memory tasks, such as locating a specific car in a busy parking lot, differ in older individuals who are cognitively normal and patients with memory loss and dementia, says Jiang.
In this new study, researchers followed older adults over 10 years. The authors report that a specific pattern of brainwaves recorded from the left-frontal region of the brain during an everyday memory task predicts a person’s risk of cognitive impairment roughly five years before clinical diagnosis. This pattern was not observed in older people who remained cognitively normal over the next 10 years.
The authors use a memory task called the Bluegrass memory paradigm in this study. In this memory task that lasted approximately 18 mins, individuals were shown a series of images and instructed to remember an image and press a button to indicate whether it matched subsequently presented images. While the participants were engaged in the mental task, the researchers recorded EEG signals known as event-related potentials (ERPs) using a 64-channel NeuroScan and scored memory performance of the participants.
“Compared to current methods using neuroimaging as biomarkers, this method of measuring can be easily set up in clinics, is non-invasive, fast and affordable. Also, reliably predicting the risk of cognitive decline in an individual is new. Our older participants will soon be able to have better version of brainwave tests here at UK [the University of Kentucky],” says Jiang. Predicting and preventing cognitive decline is very important to allow preventive measures, such as life-style changes, and for researchers to help achieve a greater quality of life for the rapidly growing aging population, he explains.
The group had previously reported that at a careful evaluation of EEG recordings showed the group means of visual memory-related potentials in the left frontal region of the brain were different between participants with normal cognition and those with aMCI older adults.
This translational study was the result of a multi-institution international collaboration among scientists from the College of Medicine, University of Kentucky, Sanders-Brown Center on Aging, UK, Oak Ridge National Laboratory, University of Tennessee, and the Institute of Psychology, Beijing China. The project was funded by the Department of Energy and the National Institute on Aging of the National Institutes of Health, USA.