Heterogeneous cerebral perfusion and network inefficiency associated with cognitive impairment in cerebral microbleeds.

BACKGROUND: Cerebral microbleeds (CMBs), a marker of cerebral small vessel disease and common in older adults, are associated with cognitive impairment. However, the neurovascular mechanisms remain incompletely understood. We investigated whether cerebral blood flow (CBF) abnormalities and CBF network changes were associated with cognitive impairment in patients with CMBs. METHODS: In this cross-sectional study, 111 participants with CMBs and 148 controls underwent neuropsychological assessment and arterial spin labeling MRI. Following propensity score matching, CBF and CBF network analyses were performed in 76 matched CMB-control pairs. Whole-brain and regional CBF were assessed, and individual CBF networks were constructed from temporal correlations among regional CBF signals. RESULTS: Participants with CMBs exhibited poorer performance in memory, language, and executive functions. Imaging analyses revealed a heterogeneous perfusion pattern in the CMB group, with relatively increased perfusion in lateral cortical regions and reduced perfusion in medial and deep brain structures. Higher temporal CBF was associated with lower cognitive scores, whereas lower caudate CBF was associated with reduced language and executive performance. Patients with CMBs also showed reduced nodal efficiency in temporal regions, including the superior temporal pole. Mediation analysis identified significant indirect associations between higher temporal CBF and lower MMSE scores through right superior temporal pole nodal efficiency. CONCLUSIONS: Cognitive impairment in patients with CMBs was associated with heterogeneous CBF abnormalities and disrupted CBF network organization. These findings suggest that perfusion abnormalities may provide clinically relevant insight into the neurovascular basis of CMB-related cognitive impairment.