Brain network changes and cognitive function after cardiac arrest

Figure 1. REVIVAL study participant inclusion flowchart. This flowchart illustrates the participant selection process for the REVIVAL study, conducted from January 2018 to February 2022. Starting with 665 OHCA survivors, 37 were ultimately included in this sub-study, 30 of whom participated in the three-month follow-up. Details of the exclusion criteria are provided within the chart. COVID-19, coronavirus disease 2019; OHCA, out-of-hospital cardiac arrest.

Figure 2. Global connectivity after out-of-hospital cardiac arrest. (A) Boxplot of the mean Fisher’s z-transformed correlation coefficients across all region-of-interest pairs, comparing resting-state global connectivity between out-of-hospital cardiac arrest patients (n = 37) and healthy controls (n = 124). Welch’s t-test indicated higher global connectivity in OHCA survivors compared to healthy controls (W = −2.98, P = 0.004). (B) Boxplot of the residuals for global connectivity adjusted for age, sex and education demonstrates diminished differences between the groups. Analysis of covariance accounting for demographics showed no significant difference in global connectivity (β = 0.01, P = 0.53). The whiskers represent the full range of the data (except for outliers that are indicated by ‘.’), while the boxes show the interquartile range. The horizontal line within each box indicates the median value. **P ≤ 0.01.

Figure 3. Resting connectivity in OHCA survivors compared to healthy controls. Heatmap illustrating Fisher’s z-transformed correlation coefficients within and between resting-state networks in OHCA survivors (n = 37, A) and healthy controls (n = 124, B). A comparative heatmap shows the differences in network connectivity between OHCA survivors and healthy controls (C). The use of propensity score weighting for demographic variables demonstrated significant decreases in within-network connectivity and increases in between-network connectivity, especially involving the frontoparietal network. This pattern suggests a potential compensatory response to maintain cognitive function in the OHCA survivor group. Asterisks (*) denotes significantly altered connectivities after adjustment for multiple testing (P < 0.015).