Mechanisms of cognitive impairment associated with cerebral infarction

Cerebral infarction is a common type of stroke with high incidence and disability rates, and most patients experience varying degrees of cognitive impairment. The manifestations and severity of post-infarction cognitive impairment are influenced by multiple interacting factors, and its pathophysiological mechanisms are highly complex, involving pericyte degeneration, excessive generation of reactive oxygen species (ROS), overproduction of glutamate, and overactivation of autophagy. After cerebral infarction, abnormal pericyte function activates neuroinflammation and facilitates the entry of inflammatory mediators into the brain; detachment of pericytes from blood vessels disrupts the integrity of the blood-brain barrier. Although angiogenesis and glial scar formation may alleviate injury, excessive scarring can inhibit neuronal regeneration. Excessive ROS trigger oxidative stress, leading to mitochondrial dysfunction, ferroptosis, and suppression of endothelial nitric oxide synthase/nitric oxide signaling, thereby damaging neurons. An excessive surge in glutamate release, coupled with insufficient clearance, results in its accumulation in the intercellular space, leading to excitotoxicity; the influx of calcium ions subsequently activates proteases and apoptotic pathways, causing neuronal death. Overactivation of autophagy alters lysosomal membrane permeability and results in leakage of lysosomal enzymes; oligodendrocyte necrosis then leads to severe demyelination, further exacerbating brain injury, although promoting the autophagic clearance of damaged mitochondria can ameliorate cognitive deficits arising from mitochondrial dysfunction.