Decreased water exchange rate across blood-brain barrier 6-12 months after admission for COVID-19 pneumonia

Motivation: A proportion of patients admitted to hospital with SARS-CoV-2 infection have cognitive deficits that persist for several months. However, the mechanisms behind persistent neurological symptoms are unclear. Blood-brain barrier (BBB) dysfunction is a possible underlying cause. Goal(s): We aimed to investigate BBB permeability in participants previously admitted to hospital with SARS-CoV-2 infection (post-acute COVID-19). Approach: We used a diffusion-prepared pseudo-continuous arterial spin labelling (DP-pCASL) to quantify water exchange rate in post-acute COVID-19 participants and controls. Results: Post-acute COVID-19 participants demonstrated lower whole brain water exchange rates across the BBB than controls, but no differences in arterial transit time or cerebral blood flow. Impact: This is the first study to report reduced water exchange across the blood brain barrier in the context of post-acute infection with SARS-CoV-2. This may implicate glymphatic system dysfunction as a mechanism for neurological symptoms associated with long COVID-19.