# Cognitive impairment after intravenous thrombolysis in mild stroke: assessment of cerebral blood flow covariance network

## TL;DR

This study finds that intravenous thrombolysis improves cognitive function in mild stroke patients by enhancing brain blood flow network properties.

## Contribution

The study reveals that IVT improves cognitive outcomes and alters cerebral blood flow network topology in mild stroke patients.

## Key findings

- IVT patients showed better performance in cognitive tests like the Clock Drawing Test and Verbal Fluency Test.
- IVT was associated with improved cerebral blood flow network properties, including higher small-worldness and global efficiency.
- Mild stroke patients had significantly lower MoCA scores compared to healthy controls.

## Abstract

Mild stroke may lead to cognitive impairment, and it remains unclear whether intravenous thrombolysis (IVT) can mitigate cognitive deficits. This study investigates whether IVT can help alleviate cognitive function impairment in patients and further explores changes in the topological properties of cerebral blood flow (CBF) networks.

This observational study prospectively enrolled 94 patients with acute mild ischemic stroke (44 IVT vs. 50 non-IVT) from two hospitals. A battery of neuropsychological tests and arterial spin labeling were performed to evaluate their cognitive functioning and CBF in 116 brain regions. Voxel-wise CBF was compared between patients and health controls. The CBF covariance network of patients was constructed by calculating across-subject CBF covariance among 116 brain regions. Network properties were calculated and compared between IVT and no-IVT groups.

The mild stroke group demonstrated significantly lower Montreal Cognitive Assessment (MoCA) scores compared to healthy controls (p < 0.001). Patients receiving IVT showed superior performance on the Trail Making Test-B (p = 0.043), Clock Drawing Test (p = 0.001), and Verbal Fluency Test (p = 0.033). Multivariate regression analysis adjusted for covariates demonstrated significant associations between IVT and cognitive outcomes: Montreal Cognitive Assessment (β = 2.85; 95% CI, 0.64–5.13), Trail Making Test-A (β = −16.90; 95% CI, −32.89–-0.90), Trail Making Test-B (β = −43.27; 95% CI, −78.78–-7.76), Hopkins Verbal Learning Test-Revised total recall (β = 3.57; 95% CI, 1.36–5.78), HVLT-R delayed recall (β = 1.53; 95% CI, 0.43–2.63), Clock Drawing Test (β = 7.09; 95% CI, 2.40–11.79), and Verbal Fluency Test (β = 3.00; 95% CI, 1.33–4.68). IVT patients exhibited higher small-worldness, clustering coefficient, and global efficiency of the network compared to non-IVT patients.

Intravenous thrombolysis demonstrated early cognitive benefits across multiple domains in patients with mild stroke. Improvement in the brain CBF covariance network properties may be the underlying mechanism.