Objectives: Prevention of cognitive decline and dementia with blood pressure lowering treatments has shown inconsistent results. We compared the effects of different classes of antihypertensive drugs on the incidence of dementia, and on cognitive function. Methods:We conducted a systematic review and included 19 randomized trials (18 515 individuals) and 11 studies (831 674 individuals) analysing the effects of antihypertensive treatment on cognition and on the incidence of dementia, respectively, in hypertensive patients without prior cerebrovascular disorders. Network meta-analysis was used for the comparison of antihypertensive classes.Results: Antihypertensive treatment, regardless of the drug class, had benefits on overall cognition [effect size 0.05, 95% confidence interval (CI) 0.02-0.07] and all cognitive functions except language. Antihypertensive treatment reduced the risk of all-cause dementia by 9%, with reference to the control group (hazard ratio 0.91, 95% CI 0.89-0.94), when randomized trials and observationnal studies were combined (n ¼ 15). Result was not significant with randomized trials alone (n ¼ 4). Angiotensin II receptor blockers (ARBs) had larger benefits than placebo on overall cognition (adjusted effect size 0.60 AE 0.18, P ¼ 0.02). ARBs were more effective than b-blockers (0.67 AE 0.18, P ¼ 0.01), diuretics (0.54 AE 0.19, P ¼ 0.04) and angiotensin-converting enzyme inhibitors (0.47 AE 0.17, P ¼ 0.04) in rank. The mean change in blood pressure did not differ significantly between the different antihypertensive drug classes. Conclusion:Our results support the notion that antihypertensive treatment has beneficial effects on cognitive decline and prevention of dementia, and indicate that these effects may differ between drug classes with ARBs possibly being the most effective.