Disrupted intracortical inhibition in the prefrontal cortex relates to cognitive dysfunction in post-COVID-19...

Dysfunction of GABA_Bergic intracortical inhibition has previously been demonstrated in the primary motor cortex of patients suffering from post-COVID19 condition (pCVD). Here, we searched for alterations in GABA_B-mediated inhibition in the prefrontal cortex (PFC), a crucial area for cognition.

Sixteen pCVD patients complaining cognitive complaints underwent a combined paired-pulse transcranial magnetic stimulation and electroencephalography (TMS-EEG) protocol of long-interval intracortical inhibition (LICI) over the left PFC. Global cognition was evaluated using the Montreal Cognitive Assessment. Twelve healthy volunteers (HV) matched for gender, age and education served as the control group.

Patients with pCVD showed lower oscillatory activity and cognitive performance compared to HV (p < 0.05). No significant LICI effects were observable in the oscillatory activity of pCVD patients, whereas these were observable in HV. A linear relationship between individual levels of gamma (r = -0.479; p = 0.030) and beta (r = -0.478; p = 0.031) frequencies inhibition and cognitive performance was observed in pCVD patients.

GABA_B- receptor mediated intracortical inhibition in the PFC is disrupted in pCVD patients with cognitive complaints and inversely correlated to cognitive performance.

TMS-EEG could be used to identify early alterations of cortical oscillatory activity in prefrontal regions related to the pCVD and inducing subtle cognitive decline.