Statin exposure and the risk of dementia in individuals with hypercholesterolaemia

OBJECTIVES: This study aimed to examine the association between statin exposure and dementia risk in individuals with hypercholesterolaemia using data from the NHIS-HEALS database between 2002 and 2015. METHODS: Subjects were classified into statin exposure and statin nonexposure groups according to medication possession ratio. Dementia was defined as those with primary diagnostic dementia codes such as F00-F03, G30, G31.1, G31.9 or G31.82. Cox proportional hazards regression models were adopted after stepwise adjustment for confounders to investigate the prospective association between statin exposure and dementia risk. RESULTS: During the follow-up period (median follow-up 11.7 years), 711 cases of dementia occurred, accounting for 11.5% of the total study population (statin exposure group, 8.2%; statin nonexposure group, 12.9%). Compared to the statin nonexposure group, fully adjusted hazard ratios (HRs) (95% confidence intervals CIs) for overall dementia in the statin exposure group were 0.63 (0.43-0.91) and 0.62 (0.50-0.78) in men and women, respectively. Compared to the statin nonexposure group, the HRs (95% CIs) for Alzheimer's disease and related dementia, vascular dementia and other types of dementia in the statin exposure group were 0.54 (0.32-0.91), 2.45 (0.69-8.68) and 0.59 (0.32-1.07), respectively, in men and 0.53 (0.38-0.73), 1.29 (0.42-3.96) and 0.70 (0.51-0.96), respectively, in women. CONCLUSIONS: Hypercholesterolaemic individuals exposed to statin had a lower risk of overall dementia and Alzheimer's disease and related dementia in both sexes, and a lower risk of other types of dementia in women, than subjects who were not exposed to statins.