Cognitive and vascular (dys)function after COVID-19.

COVID-19 is a systemic infection that causes endothelial dysfunction, contributing to severe cases. While vascular complications are well-documented, their impact on vascular structure, function, and cognition remains unclear. This cross-sectional study explored vascular and cognitive differences across patients with mild, moderate, and severe COVID-19, examining correlations between global cognitive performance and vascular parameters. This study included 83 working-age patients (30-65 years, both sexes) who recovered from COVID-19 within 6-12 months. They were grouped by severity: mild (outpatients, no oxygen support), moderate (hospitalized, conventional oxygen therapy), and severe (hospitalized, advanced oxygen therapy). Exclusions included pre-existing cognitive or neurological conditions, significant atherosclerosis, malignancies, and prior COVID-19 vaccination. Global cognitive function was assessed using the Montreal Cognitive Assessment (MoCA) test, while vascular parameters - carotid intima-media thickness (IMT), beta stiffness index (β index), mean flow velocity (MVs), maximum velocity after breath-holding (MV-BH), and breath-holding index (BHI) - were evaluated using duplex ultrasound and transcranial Doppler. Patients with severe COVID-19 had the highest carotid stiffness and poorest cerebrovascular reactivity. While MoCA scores showed no significant group differences, 23-40% had mild cognitive impairment. MoCA scores negatively correlated with β index in mild group (ρ=--0.453; p = 0.034), while MVs positively correlated with MoCA in severe cases (ρ = 0.414; p = 0.028). The association between arterial stiffness and cognitive impairment in mild cases, suggests lasting effects of SARS-CoV-2 rather than pre-existing conditions. These findings highlight carotid stiffness as a key factor in post-COVID-19 cognitive impairment, emphasizing early risk identification for timely intervention.