Dementia is a progressive neurodegenerative disease that develops most commonly in late adulthood and is predominantly characterised by cognitive decline and functional deterioration (Van Der Flier & Scheltens, 2005). The symptoms of dementia vary between patients, but the associated cognitive impairment includes lack of concentration, memory loss, agnosia, apraxia, communication and speech problems, disorientation, and deterioration in executive function (Duong, Patel, & Chang, 2017). The symptoms linked to dementia have detrimental impacts on the patient's health and quality of life, which only worsens as the disease advances. Cognitive decline is provoked by synaptic loss from dementia pathologies in the cerebral cortex that can trigger inflammation, glial and astrocyte activation, oxidative stress, and subsequent neurophysiological changes (Morrison & Baxter, 2012; Terry et al., 1991). Many subtypes of dementia have been identified in accordance with the pathology. The most common subtypes that account for 97% of cases are Alzheimer's disease (AD; 60% of cases), vascular dementia (VaD; 20%), Lewy body dementia (LBD; 10%), frontotemporal dementia (FTD; 5%) and Parkinson's disease dementia (PD; 2%) (Duong et al., 2017). Clinical characteristics can vary and may be demonstrated at different time courses, based upon the brain areas affected by each subtype (Fig. 1).

Overall, dementia affects around 47 million people worldwide (Ricci, 2019). In 2021, in the UK, the total annual cost associated with dementia was estimated to amount to £25 billion (Luengo-Fernandez & Landeiro, 2022). Consequently, the disease is an enormous public health, social and economic burden, that is only forecast to rise. In fact, due to the current ageing population, by 2050, 135 million people are predicted to be diagnosed with dementia (Ricci, 2019). Despite dementia being so prevalent, there is no curative drug at present, and available treatment only slows down its progression or masks the symptoms, by maintaining neuronal communication or limiting neuronal loss (Tisher & Salardini, 2019). Therefore, there is an extensive unmet need for preventative therapies. Targeting modifiable risk factors may be an effective strategy for the reduction in dementia incidence. Hypertension has been recognised as a modifiable risk factor, particularly for the two most prevalent subtypes: VaD, vascular lesion aetiology, and AD, classically defined by abnormal amyloid and tau accumulation. Hypertension can lead to focal brain atrophy, increased arterial stiffness, and decreased cerebral blood flow (Jochemsen et al., 2013); therefore, hypertension may be an appropriate condition to target to potentially reduce the risk of dementia. Thus, this review explores the effect that hypertension has on cognitive decline and dementia and evaluates if blood pressure (BP) control, using antihypertensive treatment, could offer protection from subsequent dementia development.