Subtle Pathophysiological Changes in Working Memory-Related Potentials and Intrinsic Theta Power in Community-Dwelling Older Adults With Subjective Cognitive Decline.

Abstract

Individuals with subjective cognitive decline (SCD) who perform normally on objective cognitive tests may have an increased risk of pathological cognitive decline and progression to Alzheimer's disease (AD) and related dementia (ADRD). Working memory is widely regarded as an early sign of pathological cognitive decline. We tested the hypothesis that older adults with SCD already exhibit aberrant neurocognitive processing underlying working memory. Electroencephalography (EEG) was recorded during a delayed match-to-sample (DMS) task and an eyes-closed resting condition in cognitively healthy community-dwelling older adults who were assigned to the SCD or Control group. The SCD and Control groups showed comparable performance on the neuropsychological tests and DMS task. The SCD group showed an enhanced right frontal target-related P300 effect during working memory retrieval and higher frontal theta power during rest. Higher theta power was associated with worse working memory performance and greater left frontal nontarget-related positivity across all older adults. Our findings suggest that older people with SCD have subtle pathophysiological changes in working memory-related potentials and intrinsic theta power, which has important implications for predicting risks and early interventions in older adults in the preclinical stage of ADRD.