Clinicians use tamsulosin, an α1‐adrenoceptor antagonist, to manage symptomatic benign prostatic hyperplasia (BPH). Because α1‐adrenoceptors are also present in the brain, the potential exists for adverse effects on cognitive functions. We explored the association between tamsulosin use and dementia risk.

We used Medicare data (2006–2012) to conduct a cohort study among patients aged ≥65 years and diagnosed with BPH. Men taking tamsulosin (n = 253 136) were matched at a 1:1 ratio using propensity‐scores to each of 6 comparison cohorts: patients who used no BPH‐medication (n = 180 926), and patients who used the following alternative‐BPH‐medications: doxazosin (n = 28 581), terazosin (n = 23 858), alfuzosin (n = 17 934), dutasteride (n = 34 027), and finasteride (n = 38 767). Assessment began following the first fill of BPH‐medication to identify incident dementia by ICD‐9 diagnosis codes. We estimated hazard ratios (HR) and 95% confidence intervals (CI) for dementia using Cox proportional hazard regression for each of the 6 propensity‐score‐matched cohort‐pairs.

The median follow‐up period for all cohorts was 19.8 months. After propensity‐score matching, the tamsulosin cohort had an incidence of dementia of 31.3/1000 person‐years compared with only 25.9/1000 person‐years in the no‐BPH‐medication cohort. The risk of dementia was significantly higher in the tamsulosin cohort, when compared with the no‐BPH‐medication cohort (HR [95% CI]: 1.17 [1.14, 1.21]) and each of the alternative‐BPH‐medication cohorts: doxazosin (1.20 [1.12, 1.28]), terazosin (1.11 [1.04, 1.19]), alfuzosin (1.12 [1.03, 1.22]), dutasteride (1.26 [1.19, 1.34]), and finasteride (1.13 [1.07, 1.19]). The significance of these findings persisted in sensitivity analyses.

Tamsulosin may increase the risk of dementia in older men with BPH.