Dementia is a common cause of disability and dependency among the elderly due to its progressive neurodegenerative nature. As there is currently no curative therapy, it is of major importance to identify new ways to reduce its prevalence. Hypertension is recognised as a modifiable risk factor for dementia, particularly for the two most common subtypes; vascular dementia (VaD) and Alzheimer's disease (AD). From the current literature, identified through a comprehensive literature search of PubMed and Cochrane Library, this review aims to establish the stage in adulthood when hypertension becomes a risk for cognitive decline and dementia, and whether antihypertensive treatment is effective as a preventative therapy.

Observational studies generally found hypertension in mid-life (age 45-64) to be correlated with an increased risk of cognitive decline and dementia incidence, including both VaD and AD. Hypertension manifesting in late life (age $\ge$ 65) was demonstrated to be less of a risk, to the extent that incidences of high blood pressure (BP) in the very elderly (age $\ge$ 75) may even be related to reduced incidence of dementias. Despite the evidence linking hypertension to dementia, there were conflicting findings as to whether the use of antihypertensives was beneficial for its prevention and this conflicting evidence and inconsistent results could be due to the methodological differences between the reviewed observational and randomised controlled trials. Furthermore, dihydropyridine calcium channel blockers and potassium-sparing diuretics were proposed to have neuroprotective properties in addition to BP lowering. Overall, if antihypertensives are confirmed to be beneficial by larger-scale homogenous trials with longer follow-up durations, treatment of hypertension, particularly in mid-life, could be an effective strategy to considerably lower the prevalence of dementia. Furthermore, greater clarification of the neuroprotective properties that some antihypertensives possess will allow for better clinical practice guidance on the choice of antihypertensive class for both BP lowering and dementia prevention.

由于其进行性神经退行性，痴​​呆症是老年人残疾和依赖的常见原因。由于目前没有治愈方法，因此寻找新的方法来降低其患病率非常重要。高血压被认为是痴呆症的一个可改变的危险因素，特别是对于两种最常见的亚型；血管性痴呆（VaD）和阿尔茨海默病（AD）。通过对 PubMed 和 Cochrane 图书馆的全面文献检索确定的现有文献，本综述旨在确定成年期高血压成为认知能力下降和痴呆风险的阶段，以及抗高血压治疗作为预防性治疗是否有效。

观察性研究普遍发现，中年（45-64 岁）高血压与认知能力下降和痴呆（包括 VaD 和 AD）发病风险增加相关。事实证明，晚年（ $\ge$ 65 岁）出现高血压的风险较小，以至于高龄老人（ $\ge$ 75）甚至可能与痴呆症发病率降低有关。尽管有证据表明高血压与痴呆有关，但对于使用抗高血压药物是否有益于预防，存在相互矛盾的发现，这种相互矛盾的证据和不一致的结果可能是由于所审查的观察性试验和随机对照试验之间的方法学差异所致。此外，二氢吡啶钙通道阻滞剂和保钾利尿剂除了降低血压外还具有神经保护作用。总体而言，如果通过更大规模、更长随访时间的同质试验证实抗高血压药物是有益的，那么治疗高血压，特别是中年时期的高血压，可能是显着降低痴呆症患病率的有效策略。此外，进一步澄清某些抗高血压药物所具有的神经保护特性，将为临床实践提供更好的指导，以选择降血压和预防痴呆的抗高血压药物。