Longitudinal Exploration of Cortical Brain Activity in Cognitive Fog: An EEG Study in Patients with and without Anosmia

Background: Long-Covid, characterized by persistent symptoms following acute Covid-19 infection, represents a complex challenge for the scientific community. Among the most common and debilitating manifestations, cognitive fog is a neurological disorder characterized by mental confusion and cognitive difficulties. In this study, we investigated the long-term effects of previous Covid-19 infection on cortical brain activity in patients experiencing cognitive fog symptoms in the medium and long term. Methods: A total of 40 subjects (20 females and 20 males) aged between 45 and 70 years (mean age (M) = 59.78, standard deviation (SD) = 12.93) participated in this study. This sample included individuals with symptoms of cognitive fog, both with and without anosmia, and a control group comprised of healthy subjects. All electroencephalography (EEG) data were collected in two sessions, 1 month and 8 months after recovery from Covid-19, to measure the neurophysiological parameters of P300 and beta band rhythms. Results: The results revealed significant differences in the neurophysiological parameters of P300 and beta band rhythms in subjects affected by cognitive fog, and these alterations persist even 8 months after recovery from Covid-19. Interestingly, no significant differences were observed between the participants with anosmia and without anosmia associated with cognitive fog. Conclusions: These findings provide a significant contribution to understanding the long-term effects of Covid-19 on the brain and have important implications for future interventions aimed at managing and treating brain fog symptoms. The longitudinal assessment of cortical brain activity helps highlight the persistent impact of the virus on the neurological health of Long-Covid patients.