Abstract: Objectives To investigate the association between single nucleotide polymorphism (SNP) of proprotein convertase subtilisin/kexin type 9 (PCSK9) rs2479409 and cognitive impairment. Methods In this population-based cohort study conducted in Rugao, Jiangsu province, China, a total of 1707 participants aged 70-84 years old were included. The cognitive impairment was assessed by revised Hasegawa Dementia Scale (HDS-R). Their SNPs rs2479409 of PCSK9 were examined. Results According the HDS-R, there were 789 cases in cognitive impairment group and 918 cases in control group. GG and AG were major genotype of rs2479409. The distribution of allele frequency and genotype frequency of rs2479409 was significant different between Cognitive impairment group and the control group (P < 0.05). A allele was a protective factor for cognitive impairment, and risk of cognitive impairment increased 1.66 folds in GG genotype compared with AA genotype GG genotype （OR=1.66，95%CI 1.16-2.36，P<0.01）, the significance remained after adjusting for confounders (P < 0.05). Conclusions SNP rs2479409 of PCSK9 gene is associated with cognitive impairment.

Key words: PCSK9, SNP, dementia, cognition