Processing Speed Impairment After Anterior Communicating Artery Aneurysm Rupture Assessed Using the Wechsler Adult Intelligence Scale: An Observational Study

Background Subarachnoid hemorrhage (SAH) commonly causes subtle, but functionally disabling, cognitive impairment. Although prior studies have emphasized the mechanisms of diffuse brain injury, the relationship between aneurysm location and domain-specific cognitive deficits remains unclear. Processing speed is a pivotal factor influencing post-SAH functional outcomes; however, it remains poorly understood, although it is known to depend on the integrity of the anterior cingulate cortex (ACC), located adjacent to the anterior communicating artery (Acom). This study investigated whether co-ruptured SAH selectively impairs processing speed using the Wechsler Adult Intelligence Scale (WAIS). Methods Twenty-nine patients with SAH (August 2016 to August 2025) underwent acute-phase neuropsychological evaluation using the WAIS-III/IV, including five indices: the Full-Scale IQ (FSIQ), Verbal Comprehension Index (VCI), Perceptual Reasoning Index (PRI), Working Memory Index (WMI), and Processing Speed Index (PSI). The Hasegawa Dementia Scale–Revised (HDS-R) was used as the screening measure. Multivariate linear regression was applied to examine predictors of PSI. Group comparisons between Acom and non-Acom SAH were conducted using Welch’s t-tests. Within-group differences were evaluated using the Friedman and Wilcoxon post-hoc tests. Interhemispheric hematoma thickness in the frontal horn-callosal rostrum (FH–CR) and Callosal Genu (CG) planes were quantified on admission CT and correlated with the PSI. Results PSI was markedly lower (82.9 ± 12.6; mean ± SD) than other WAIS indices (FSIQ, VCI, PRI, and WMI). Regression analysis identified Acom aneurysm location as the only independent predictor of lower PSI (β = −15.68, p = 0.044). The Acom group demonstrated significantly reduced PSI compared with the non-Acom group (72.9 ± 9.95 vs. 88.11 ± 10.56, p = 0.00109; Welch’s t-test), with no differences in other indices. Hematoma thickness at both FH–CR and CG planes was significantly greater in the Acom group and correlated negatively with PSI (ρ = −0.626 and − 0.593, respectively). Conclusion Acom-ruptured SAH is associated with a selective impairment in processing speed during the acute phase, likely reflecting the region-specific vulnerability of the anterior cingulate structures. Acute-phase WAIS assessment enables the sensitive detection of these deficits and may guide early targeted rehabilitation.