Statin reduces the risk of dementia in diabetic patients receiving androgen deprivation therapy for prostate cancer

Background: Androgen deprivation therapy (ADT) has been reported to increase the risk of dementia. Statin use decreases the risk of dementia. This study is aimed to investigate the association of statin use and dementia in type 2 diabetic (T2DM) patients receiving ADT. Methods: Using the National Health Insurance Research Database of Taiwan, we conducted a population-based nationwide cohort study of T2DM patients newly diagnosed with prostate cancer (PCa) between 1998 and 2013. To test statin effects on dementia in T2DM patients receiving ADT, cox proportional hazards models with 1:1 propensity score-matched analysis were used. We divided the study subjects into a statin group and a statin-naive group. The primary outcome was dementia. Results: Of the 9855 selected T2DM patients newly diagnosed with PCa between 1998 and 2013, 5427 patients received ADT for their PCa. After propensity score matching, 1006 statin users and 1006 non-statin users were included in the study cohort, with a mean follow-up period of 3.5 years for the statin group. Among those patients, 179 (8.7%) were newly diagnosed with dementia. A propensity score-matched analysis (hazard ratio = 0.70, 95% confidence interval = 0.52–0.94) demonstrated a significantly decreased risk of subsequent dementia in the statin users with an absolute risk reduction by 1%. A significant decrease in the risk of dementia with increasing statin duration was also demonstrated (P for trend = 0.002). Conclusions: Statin use in T2DM patients receiving ADT for PCa had decreased risk of dementia, with statin adherence and intensity augmenting this benefit.