Work

Decreased frontal gamma activity in Alzheimer’s disease patients

Year: 2023

Type: article

Abstract: In Alzheimer’s disease (AD) animal models, synaptic dysfunction has been recently linked to a disorder of high-frequency neuronal activity. In patients, a clear relation between AD and oscillatory activity remains elusive. Here, we attempt to shed light on this relation by using a novel approach combining transcranial magnetic stimulation and electroencephalography (TMS-EEG) to probe oscillatory activity in specific hubs of the fronto-parietal network in a sample of 60 mild-to-moderate AD patients. 60 mild-to-moderate AD patients and 21 age-matched healthy volunteers (HV) underwent three TMS-EEG sessions to assess cortical oscillations over the left dorso-lateral prefrontal cortex (l-DLPFC), the precuneus (PC) and the left posterior parietal cortex (l-PPC). To investigate the relations between oscillatory activity, cortical plasticity and cognitive decline, AD patients underwent a TMS-based neurophysiological characterization and a cognitive evaluation at baseline. The latter was repeated after 24 weeks to monitor clinical evolution. AD patients showed a significant reduction of frontal gamma activity as compared to age-matched HV. In addition, AD patients with a more prominent decrease of frontal gamma activity showed a stronger impairment of LTP-like plasticity and a more pronounced cognitive decline at subsequent follow-up evaluation at 24 weeks. Our data provide novel evidence that frontal lobe gamma activity is dampened in AD patients. The current results point to the TMS-EEG approach as a promising technique to measure individual frontal gamma activity in patients with AD. This index could represent a useful biomarker to predict disease progression and to evaluate response to novel pharmacological therapies. Research Category and Technology and Methods Clinical Research: 10. Transcranial Magnetic Stimulation (TMS) Keywords: TMS, EEG, Alzheimer's Disease, Oscillations

Source: Brain stimulation

DOI: 10.1016/j.brs.2023.01.596