Background: The therapeutic effect and mechanism of protocatechuic aldehyde (PAL) on vascular dementia (VaD) were studied from a multi-group perspective. Methods: The pharmacological property of PAL was assessed by using both an in vivo two-vessel occlusion (2VO) rat model and an in vitro astrocyte-neuron co-culture system with oxygen-glucose deprivation (OGD) injury. On the basis of neurobehavioral test, Morris' water maze test and hematoxylin and eosin staining, the pathological transformation...