High Blood Pressure and Dementia

High blood pressure not only damages blood vessels and organs. Arterial hypertension is one of the risk factors for vascular dementia. Vascular dementia is caused by circulatory disorders of the small blood vessels that supply the deeper structures of the brain. These disorders are usually due to thickening of the vessel walls and the resulting reduced blood flow.

For a long time, dementia was only associated with blood pressure in cases involving those over 80 years old with very low blood pressure. In this rather rare context, the reduced brain perfusion due to low blood pressure is the decisive factor for dementia-like symptoms.

However, high blood pressure - and this starts even at high-normal values - chronically and progressively impairs brain function. The reason is suspected to be pressure-related damage to the smallest brain arteries. These damages or their consequences can be detected in a brain MRI as small brain infarcts or as damage to the large conduits in the brain.

In various studies on reducing the risk of dementia, it was shown that patients benefit from consistent treatment of their high blood pressure.

In the Syst-Eur Study Extension published in 2002, it was observed that the risk of developing dementia in the participant group whose high blood pressure was consistently treated decreased by about half over the four-year observation period.

Another research group observed 300 Alzheimer patients over a period of two and a half years. Here, too, it was shown that patients whose cardiac risk factors (such as high blood pressure) were continuously treated performed significantly better cognitively than the group whose risk factors remained untreated. In the latter, the loss of mental performance progressed rapidly.

New studies have now shown that strict blood pressure control is relevant not only in old age to prevent dementia. The University of California studied 579 people with an average age of 39.2 years. Brain scans revealed changes in the brains of those who already had high blood pressure: they were prematurely aged. Simply put, the brains of 30-year-olds with high blood pressure looked like the brains of 40-year-olds with normal blood pressure. Thus, it was not the age of the affected individuals that proved decisive, but the level of blood pressure. Even high-normal to mildly hypertensive values lead to changes in brain structure.

An analysis of the British Whitehall-II study provides concrete numbers. Over a period of 32 years, 4.5 percent of the 8,600 participants developed dementia. The systolic blood pressure was over 130 mmHg in 29 percent of the subjects at the age of 50. Above this threshold, 6.3 percent developed dementia, while only 3.7 percent were affected at lower blood pressure values. When adjusted for other risk factors such as smoking, overweight, and the like, there is a relative increase in the dementia rate of 38 percent.

Another threshold occurred at systolic values over 150 mmHg: here, the risk of developing dementia doubled again. This was observed regardless of the occurrence of other cardiovascular diseases. Thus, the risk of developing dementia remains elevated to the same extent, even if the hypertensive individual has no cardiovascular problems.

The connection between elevated blood pressure values and dementia was also shown in a Korean study. It was observed that in young seniors, who were 66 years old, the risk of vascular dementia was already increased at systolic blood pressure values over 130 mmHg. The risk of developing Alzheimers dementia increased at systolic blood pressure values starting from 160 mmHg.

A Chinese study published in November 2023 supports these findings. Approximately 34,000 individuals aged at least 40 from Chinese villages were examined. The participants had high-normal blood pressure values or mild hypertension. In some of the villages, the usual therapy for high blood pressure was conducted, while in others, residents received intensive high blood pressure therapy aimed at lowering blood pressure to below 130 mmHg systolic and 80 mmHg diastolic. After 4 years, it was shown that in the villages of the intervention group, which had received intensive high blood pressure therapy, the dementia risk of participants was 15% lower, and the risk of cognitive impairments was even 16% lower than in the villages of the control group.

Treating high blood pressure is therefore not only essential for the cardiovascular system but also for the brain. When blood pressure is lowered, for example, through lifestyle changes or medication, the risk of dementia also decreases.

However, equally important in this context is prevention, meaning regular monitoring of blood pressure, even when no high blood pressure is present. Only in this way can subsequent diseases be counteracted in a timely manner.

Sources

By Sabine Croci. This article is medically reviewed. Last updated (01/2024).
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High Blood Pressure and Dementia

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