Background Evidence concerning the potential repurposing of antihypertensives for Alzheimer’s disease prevention is inconclusive. We used Mendelian randomization, which can be more robust to confounding by indication and patient characteristics, to investigate the effects of lowering systolic blood pressure (SBP), via different antihypertensive drug classes, on Alzheimer’s disease.Methods We used summary statistics from genome wide association studies of SBP (from UK Biobank) and Alzheimer’s disease (from the International Genomics of Alzheimer’s Project) in a two-sample Mendelian randomization analysis. We identified single nucleotide polymorphisms (SNPs) that mimic the action of antihypertensive targets and estimated the effect of lowering SBP, via antihypertensive drug classes, on Alzheimer’s disease. We also report the effect of lowering SBP on Alzheimer’s disease by combining all drug targets and without consideration of the associated drugs.Results There was limited evidence that lowering SBP, via antihypertensive drug classes, affected Alzheimer’s disease risk. For example, calcium channel blockers had an odds ratio (OR) per 10mmHg lower SBP of 1.53 (95% confidence interval (CI): 0.94 to 2.49; p=0.09; SNPs=17). We also found limited evidence for an effect of lowering SBP on Alzheimer’s disease when combining all drug targets (OR per 10mmHg lower SBP: 1.14; 95%CI: 0.83 to 1.56; p=0.41; SNPs=59) and without consideration of the associated drug targets (OR per 10mmHg lower SBP: 1.04; 95%CI: 0.95 to 1.13; p=0.45; SNPs=153).Conclusions Lowering SBP itself is unlikely to affect risk of developing Alzheimer’s disease. Consequently, if specific antihypertensive drug classes do affect risk of Alzheimer’s disease, they are unlikely to do so via SBP.KEY MESSAGES

Repurposing antihypertensive drugs for the prevention of Alzheimer’s disease: a Mendelian Randomization study