Hypersynchronization, a common feature along the AD process

Abstract

AbstractBackgroundIn the last decade there are more and more literature indicating that subjects at different stages of Alzheimer´s Disease (AD) continuum, have a disrupted organization of their anatomo‐functional networks. Neurophysiological findings with MEG have indicated an increased brain synchrony between different brain regions across different stages of the disease. In this talk we will concentrate on these neurophysiological findings in humans comparing magnetoencephalography (MEG) findings with clinical and current biomarkersMethodIn a series of studies using magnetoencephalography, we have recorded resting state activity in patients with Mild Cognitive Impairment (MCI), Subjective Cognitive Decline (SCD) and in healthy subjects at preclinical stage or at risk for developing dementia. We used functional connectivity in the source space to assess how the brain oscillatory activity synchronize across brain regions. MEG findings will be compared with clinical stages, amyloid‐PET, cerebrospinal fluid (p‐tau), or brain atrophy.ResultMCI patients and SCD participants showed an increased functional connectivity values in anterior regions of the brain in the alpha band. This was in combination with a posterior hyposynchronization which was slightly higher in MCI patients compared to SCD. MCI patients who did convert to dementia showed hypersynchronization between anterior cingulate cortex and posterior regions in the alpha band. A second MEG scan on MCI converters (when they were at the dementia stage) showed a decrease in brain synchrony in a similar region, indicating that hypersynchrony accelerate the process of network dysfunction (the “X Model”). These profiles of brain synchrony were evaluated in comparison with biomarkers. MCI patients with elevated p‐tau in the CSF showed again increased synchronization between anterior cingulate and the medial temporal lobe. Healthy subjects (no memory complaints, no brain atrophy, no hypometabolism) with a positive amyloid PET showed as well increased brain synchrony. Finally, young relatives of AD patients showed increased phase synchrony in similar brain regions than that found in MCI patients in the alpha band.ConclusionAll these findings together indicate that hypersynchronization of the brain networks could be an excellent non‐invasive biomarker for tracking the disease and evaluate interventions.