Supplementary Material for: Electroencephalographic abnormalities in a patient suffering from long-term neuropsychological complications following SARS-Cov2 infection

Introduction
Emotional apathy has recently been identified as a common symptom of long COVID. While recent meta-analyses have demonstrated generalized EEG slowing with the emergence of delta rhythms in patients hospitalized for severe SARS-Cov2 infection, no EEG study or dopamine transporter scintigraphy (DaTSCAN) have been performed in patients with long COVID presenting with apathy. The objective of this case report was to explore the pathophysiology of neuropsychological symptoms in long COVID.
Case presentation
A 47-year-old patient who developed a long COVID with prominent apathy following an initially clinically mild SARS-Cov2 infection, underwent neuropsychological assessment, cerebral MRI, DaTSCAN, and resting-state high-density EEG seven months after SARS-Cov2 infection. The EEG data were compared to those of 21 healthy participants. The patient presented with apathy, cognitive difficulties with dysexecutive syndrome, moderate attentional and verbal episodic memory disturbances, and resolution of pre-morbid mild gaming disorder, mild mood disturbances, and sleep disturbances. His MRI and DaTSCAN were unremarkable. EEG revealed a complex pattern of oscillatory abnormalities compared to the control group, with a strong increase in whole-scalp delta and beta band activity, as well as a decrease in alpha band activity. Overall, these effects were more prominent in the frontal-central-temporal region. Conclusion
These results suggest widespread changes in EEG oscillatory patterns in a patient with long Covid characterized by neuropsychological complications with prominent apathy. Despite the inherent limitations of a case report, these results suggest dysfunction in the cortical networks involved in motivation and emotion.