Education and amyloid load affect posterior lobe function in subjective memory complainers: an EEG‐fMRI study

Abstract

AbstractBackgroundIndicators of cognitive reserve (CR) moderate the effect of brain pathophysiology on cognitive deficits in the Alzheimer’s Disease (AD) continuum. In a previous study on individuals with subjective memory complaint (SMCs), a condition at risk for AD, from the INSIGHT‐preAD cohort, we found that CR using educational attainment (Edu) as a proxy altered the association of amyloid load with neurophysiological mechanisms generating posterior electroencephalographic (EEG) alpha rhythms in quiet wakefulness.MethodHere, we tested the hypothesis of an interaction between Edu and cerebral amyloid‐b load by analyzing the association between posterior alpha rhythms and functional magnetic resonance imaging connectivity (fMRI), among cholinergic basal forebrain (BF), thalamus, and cortical regions forming the Visual Network (VN).ResultResults showed a significantly positive association between posterior alpha rhythms and above‐mentioned functional connectivity in the SMC seniors with low brain amyloid accumulation and high education attainment (SMCneg Edu+), characterized by the amplest posterior alpha rhythms. This effect may be related to the neuroprotective effect of CR. On the contrary, SMC seniors with high brain amyloid accumulation and high education attainment (SMCpos Edu+) showed a trend towards the greatest negative association between posterior alpha rhythms and functional connectivity, possibly reflecting the compensatory effect related to high CR and high brain amyloidosis (see Figure).ConclusionThe present results suggest that, in SMC seniors, high CR affects the relation between cortical neural synchronization mechanisms generating posterior rsEEG alpha rhythms and functional connectivity involving the ascending cholinergic system and the VN. Unfortunately, these CR effects may be annulled at earlier stages of Alzheimer’s amyloid pathophysiology.