%0 Journal Article %J J Alzheimers Dis %D 2021 %T Memory-Related Frontal Brainwaves Predict Transition to Mild Cognitive Impairment in Healthy Older Individuals Five Years Before Diagnosis. %A Jiang, Yang %A Li, Juan %A Schmitt, Frederick A %A Jicha, Gregory A %A Munro, Nancy B %A Zhao, Xiaopeng %A Smith, Charles D %A Kryscio, Richard J %A Abner, Erin L %K Aged %K Brain Waves %K Cognition %K Cognitive Dysfunction %K Electroencephalography %K Female %K Humans %K Longitudinal Studies %K Male %K Memory, Short-Term %K Neuropsychological Tests %K Prodromal Symptoms %X

BACKGROUND: Early prognosis of high-risk older adults for amnestic mild cognitive impairment (aMCI), using noninvasive and sensitive neuromarkers, is key for early prevention of Alzheimer's disease. We have developed individualized measures in electrophysiological brain signals during working memory that distinguish patients with aMCI from age-matched cognitively intact older individuals.

OBJECTIVE: Here we test longitudinally the prognosis of the baseline neuromarkers for aMCI risk. We hypothesized that the older individuals diagnosed with incident aMCI already have aMCI-like brain signatures years before diagnosis.

METHODS: Electroencephalogram (EEG) and memory performance were recorded during a working memory task at baseline. The individualized baseline neuromarkers, annual cognitive status, and longitudinal changes in memory recall scores up to 10 years were analyzed.

RESULTS: Seven of the 19 cognitively normal older adults were diagnosed with incident aMCI for a median 5.2 years later. The seven converters' frontal brainwaves were statistically identical to those patients with diagnosed aMCI (n = 14) at baseline. Importantly, the converters' baseline memory-related brainwaves (reduced mean frontal responses to memory targets) were significantly different from those who remained normal. Furthermore, differentiation pattern of left frontal memory-related responses (targets versus nontargets) was associated with an increased risk hazard of aMCI (HR = 1.47, 95% CI 1.03, 2.08).

CONCLUSION: The memory-related neuromarkers detect MCI-like brain signatures about five years before diagnosis. The individualized frontal neuromarkers index increased MCI risk at baseline. These noninvasive neuromarkers during our Bluegrass memory task have great potential to be used repeatedly for individualized prognosis of MCI risk and progression before clinical diagnosis.

%B J Alzheimers Dis %V 79 %P 531-541 %8 2021 %G eng %N 2 %1 https://www.ncbi.nlm.nih.gov/pubmed/33337367?dopt=Abstract %R 10.3233/JAD-200931 %0 Journal Article %J J Alzheimers Dis %D 2016 %T Altered Brain Activities Associated with Neural Repetition Effects in Mild Cognitive Impairment Patients. %A Yu, Jing %A Li, Rui %A Jiang, Yang %A Broster, Lucas S %A Li, Juan %X

Older adults with mild cognitive impairment (MCI) manifest impaired explicit memory. However, studies on implicit memory such as repetition effects in persons with MCI have been limited. In the present study, 17 MCI patients and 16 healthy normal controls (NC) completed a modified delayed-match-to-sample task while undergoing functional magnetic resonance imaging. We aim to examine the neural basis of repetition; specifically, to elucidate whether and how repetition-related brain responses are altered in participants with MCI. When repeatedly rejecting distracters, both NC and MCI showed similar behavioral repetition effects; however, in both whole-brain and region-of-interest analyses of functional data, persons with MCI showed reduced repetition-driven suppression in the middle occipital and middle frontal gyrus. Further, individual difference analysis found that activation in the left middle occipital gyrus was positively correlated with rejecting reaction time and negatively correlated with accuracy rate, suggesting a predictor of repetition behavioral performance. These findings provide new evidence to support the view that neural mechanisms of repetition effect are altered in MCI who manifests compensatory repetition-related brain activities along with their neuropathology.

%B J Alzheimers Dis %V 53 %P 693-704 %8 2016 May 11 %G eng %N 2 %1 http://www.ncbi.nlm.nih.gov/pubmed/27176074?dopt=Abstract %R 10.3233/JAD-160086