A few years back, scientists made an exciting discovery: lowering blood pressure could help prevent mental decline in people over 50 who have high blood pressure.
However, it was unclear if this approach was safe or effective for those with low diastolic blood pressure (the bottom number in a reading).
Some believed that intensive control might increase the risk of dementia in this group.
Now, a new study from China has shown that lowering systolic blood pressure (the top number) intensively is not harmful to people with low diastolic blood pressure.
In fact, those who reduced their systolic levels intensively had a lower risk of developing dementia or mild cognitive impairment, regardless of their initial diastolic levels.
Dr. Rebecca Gottesman, who was not involved in the study, said that the research supports the idea that intensive blood pressure control is safe and beneficial for most people.
The study also helps fill a gap in our knowledge about who can benefit from intensive blood pressure control.
Blood pressure readings have two numbers. The top number measures the force against artery walls when the heart beats (systolic pressure), while the bottom number measures the same force between beats (diastolic pressure).
High systolic blood pressure, especially during midlife, is a risk factor for cognitive decline and dementia. Lowering it has been shown to reduce that risk.
Mild cognitive impairment (MCI) is when someone has more difficulty thinking and remembering than others their age.
Dementia causes even more severe challenges, making it hard to perform basic daily tasks.
The new study used data from a previous trial that tested intensive blood pressure control in people aged 50 and older with high systolic blood pressure.
The participants were split into two groups: one with an intensive control target (less than 120 mmHg) and another with a standard control target (less than 140 mmHg).
Researchers measured cognitive function at the beginning and throughout the study.
The trial was stopped early when it was clear that intensive blood pressure control greatly reduced the risk of heart disease and death.
However, researchers continued to analyze the data and found that intensive control had a significant impact on reducing MCI.
This latest study looked deeper into the relationship between intensive blood pressure control and dementia risk.
It focused on whether intensive control could harm cognitive function in people with very low diastolic blood pressure and whether it could lower blood flow to the brain, which is linked to faster cognitive decline and higher dementia risk.
The results showed that people with the lowest diastolic pressure levels had higher rates of cognitive decline than those with higher diastolic pressure.
However, regardless of diastolic pressure, those in the intensive blood pressure-lowering group had lower rates of probable dementia or mild cognitive impairment than those in the standard group.
There was no evidence that intensive blood pressure control harmed cerebral blood flow.
The findings suggest that intensive blood pressure control may have greater cognitive benefits for people with very high diastolic pressure compared to those with very low diastolic levels.
However, more research is needed to fully understand these results.
People with very low diastolic pressure may already be experiencing early stages of dementia, which could explain the lack of benefits seen in this group.
The study’s main limitation is the short follow-up period (less than four years) due to the early halt of the trial.
Longer studies may provide more conclusive results about the safety of intensive blood pressure control for people with very low diastolic levels.
If you care about blood pressure, please read studies about unhealthy habits that could increase high blood pressure risk, and most widely used high blood pressure drug may harm heart health.
For more information about brain health, please see recent studies that cranberries could help boost memory, and higher magnesium intake could help benefit brain health.
The study was published in Hypertension.
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