Forrest proved that the KP pathway and folate are involved in cognitive impairment after heart surgery, and more importantly, inhibition of the KP pathway can prevent brain damage caused by ischemia and reduce central inflammation-related mortality, suggesting that the KP pathway can be used as an important potential target for the promotion of drugs for the prevention and treatment of brain damage or POCD. The gene discussed is NPPA; the disease is Cognitive impairment.