Background The incidence of cognitive impairment-related diseases such as Alzheimer's disease is increasing. Alpha1-antichymotrypsin(ACT) plays a special role in cognitive dysfunction. Objective This paper summarizes the correlation between ACT and cognitive dysfunction, and analyses its mechanism. Content This paper describes the pathophysiology and genetic mechanisms of ACT in cognitive function. Trend To some extent, the plasma levels of ACT in patients correlate with the degree of cognitive deterioration, however, the effect of ACT as a predictor in cognitive function still needs to be further expored.