State of Brain Networks in Long Covid: Post Mild to Moderate Acute Covid -19 Disease

Abstract

Background: Long Covid is a well-known entity in patients who recovered from acute Covid-19 disease and this phase is dominated by neurological complaints chiefly fatigue, palpitations and sleep disorders. This study was designed to assess the functional connectivity of the major brain networks in patients who recovered from mild to moderate Covid-19 disease. Methods: A observational study comprising of 100 consecutive symptomatic patients without any prior neurological disorder was conducted using resting state (rs) functional MRI. Post processing was done for both in-network and between-network connectivity of eight major brain networks and results statistically analyzed and correlated with clinical symptoms. Results: 91% patients presented with fatigue and showed marked reduced activity of medial frontal cortex (MFC) of the default mode network (DMN) with reduced functional connectivity (FC) of DMN with Salience (SALIEN) network, Sensorimotor network (SMN), Dorsal attention network (DAN) with compensatory overactivity of right lateral posterior parietal node (LPP) which was a characteristic feature. PTSD was second commonest with 80% patients showing reduced FC of DMN, SALIEN, Language network (LANGN) with overactivity of Visual network (VISN) and the cerebellum. 77% patients had anosognosia and showing characteristic overactivity of basal ganglia network (BGN) with reduced FC of DMN, SALIEN, SMN. Conclusion: Long covid patients show major altered FC of both in and between networks with DMN being most commonly affected with severely reduced FC of MFC. Fatigue patients showed a characteristic signature of overactive right LPP. PTSD patients had increased VISN and cerebellar BOLD activity while in anosgnosia a characteristic BGN over activity was seen.