Cognitive impairment is a major sequela following aneurysmal subarachnoid hemorrhage (aSAH), severely influencing patients' long-term quality of life. Its mechanism of occurrence is complex and has not been fully clarified to date. In recent years, the role of the gut microbiota in neurological diseases has gradually been revealed, providing a compelling theoretical framework for exploring the gut-brain axis in aSAH-induced cognitive impairment. Recognizing the limitations of current cross-sectional evidence, this review explicitly aims to propose testable hypotheses rather than establish definitive causation. In this study, we propose the novel "gut-derived secondary hit" hypothesis, aiming to explore how secondary gut microbiota dysbiosis, triggered by primary central nervous system injury following aSAH, may act as a potential modulator contributing to long-term cognitive impairment through altered shifts in the metabolite profile. In this review, we outline the clinical manifestations and pathological mechanisms of aSAH-induced cognitive impairment, as well as the observed shifts in gut microbial composition. We further deeply explore the complex pathways through which the gut microbiome and its derived metabolites may be associated with cognitive impairment. In addition, incorporating recent advances, we discuss prospective microbiome-targeted therapeutic strategies, providing a translational perspective for future mechanistic studies and the clinical prevention and treatment of aSAH-induced cognitive impairment.
