Abstract:Alzheimer disease( AD) is the most common cause of dementia. The pathogenesis of AD is complex and can't be cured at present. Apolipoprotein E( ApoE) is a kind of lipid transporter in vivo, and its subtype apolipoprotein E4( ApoE4) is considered to be the strongest risk factor for AD. In recent years, with the in-depth study of ApoE4, it has been found that ApoE4 plays new important roles in the occurrence and development of AD, such as the mediation of immune response, the destruction of blood-brain barrier, the damage of mitochondria and so on. This paper summarizes the latest research progress on the effect of ApoE4 in AD, and provides some new ideas and references for the prevention and treatment of AD.