Recent research highlights a significant connection between untreated hypertension and the onset of dementia. Hypertension is the most common condition in Australian general practice, affecting approximately 6.8 million Australians—about one-third of all adults—in 2022. Alarmingly, around 50% of those with hypertension remain undiagnosed, while 18% are diagnosed but have uncontrolled blood pressure. Only 32% are both diagnosed and effectively managed.
Among those over 65, 34% have a prior diagnosis of hypertension, yet 39% still exhibit high blood pressure levels. Worryingly, the prevalence of elevated blood pressure in community screenings has risen from 21.5% in 2011-12 to 23.3% in 2022.
So, why is hypertension so frequently underdiagnosed and undertreated? The reasons are varied. Hypertension is often asymptomatic, can fluctuate during measurements, and its long-term consequences may not be immediately apparent. Additionally, outdated beliefs persist that high blood pressure is normal or even healthy in older adults. Public awareness of hypertension’s risks remains low, especially regarding its emerging link to dementia.
Research Findings on Hypertension and Dementia
Our teams at the Centre for Healthy Brain Ageing and the George Institute at the University of New South Wales have been investigating this relationship. In a 2019 meta-analysis, we found a clear correlation between mid-life hypertension and Alzheimer’s dementia (AD).
Specifically, stage 1 hypertension (systolic blood pressure >140 mmHg) was associated with an 18% increased risk of AD, while stage 2 hypertension (>160 mmHg) showed a 25% increase. A subsequent meta-analysis in 2020 indicated that mid-life hypertension raised the risk of all-cause dementia by 19-55%. However, studies on late-life hypertension yielded mixed results.
In our recent studies published in 2023 and 2024, we analyzed data from over 34,500 participants aged 60 and older from 15 countries. We discovered that individuals with untreated hypertension faced a 42% higher risk of dementia and a 36% increased risk of AD compared to those without a previous diagnosis of hypertension. Conversely, those with treated hypertension did not show a significantly elevated risk for either condition compared to healthy individuals. In fact, treated patients had a substantially lower risk—26% lower for dementia and 42% lower for AD—indicating that effective treatment can mitigate these risks.
Implications for Treatment
Our analysis revealed that a single measure of blood pressure in late life did not significantly correlate with dementia risk. This suggests that multiple measurements may be necessary for accurate risk assessment in older patients. Notably, our study included participants from underrepresented populations in Nigeria, the Republic of Congo, and the Central African Republic, showing no significant differences based on race or sex.
While our studies have limitations due to their observational nature—potentially confounded by non-random differences between treated and untreated groups—the findings align with recent clinical trials. A meta-analysis from 2022 indicated that antihypertensive treatment reduced dementia risk by 13%, while a Lancet commission report stated that hypertension increases dementia risk by 20%.
Overall, the evidence strongly supports the ongoing use of antihypertensive medications as an essential strategy for preventing dementia both in Australia and globally. As public health priorities shift toward addressing modifiable risk factors for dementia, hypertension management will play a critical role in safeguarding cognitive health as populations age.
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