Several years ago, a study published in the Journal of the American Medical Association (JAMA) suggested that intensive blood pressure control could potentially reduce the risk of cognitive decline in individuals aged 50 and older with high blood pressure.
However, concerns remained regarding the safety and effectiveness of this strategy, particularly for those whose diastolic blood pressure (the lower number in a blood pressure reading) was already low.
Some data suggested that aggressive blood pressure control might increase the risk of dementia in this subgroup.
Now, a new study conducted by researchers in China provides valuable insights into this matter, revealing that intensive systolic (the top number) blood pressure control does not appear to be harmful to individuals with low diastolic blood pressure.
In fact, intensive systolic blood pressure reduction was associated with a decreased risk of probable dementia or mild cognitive impairment, regardless of the initial diastolic blood pressure levels.
Reaffirming the Safety of Intensive Blood Pressure Control
Dr. Rebecca Gottesman, Chief of the Stroke Branch at the National Institute of Neurological Disorders and Stroke Intramural Research Program in Bethesda, Maryland, commends the study’s findings.
She highlights that this research addresses a significant gap in scientific knowledge regarding the safety of intensive blood pressure control, especially for individuals with low diastolic blood pressure.
“I think this further supports the general notion that for most people, intensive blood pressure control is safe and has potential benefits,” says Dr. Gottesman.
She emphasizes that this study offers confidence that intensive blood pressure control is safe across various diastolic blood pressure levels.
Understanding Blood Pressure Readings
A standard blood pressure reading comprises two numbers: systolic and diastolic.
The top number (systolic) measures the force of blood against artery walls when the heart beats, while the bottom number (diastolic) measures the same force between heartbeats.
Previous research has established that high systolic blood pressure, especially during midlife, increases the risk of cognitive decline and dementia. Lowering systolic blood pressure has been shown to reduce this risk.
Differentiating Mild Cognitive Impairment and Dementia
Before delving into the recent study’s findings, it’s important to understand the distinction between mild cognitive impairment (MCI) and dementia.
MCI is characterized by experiencing more difficulties in thinking, remembering, and reasoning compared to individuals of the same age.
Dementia, on the other hand, represents a more severe cognitive decline that interferes with basic daily functioning.
The SPRINT MIND Trial
To investigate the impact of intensive blood pressure control on dementia risk, researchers analyzed data from the SPRINT MIND trial (Systolic Blood Pressure Intervention Trial—Memory and Cognition In Decreased Hypertension).
This trial enrolled individuals aged 50 and older with high systolic blood pressure and randomly assigned them to two groups: one with an intensive blood pressure control target (less than 120 mmHg) and another with a standard target (less than 140 mmHg).
Cognitive function was assessed through a series of tests at the trial’s outset and during follow-up.
The SPRINT study, initially planned for five years, was stopped after slightly more than three years due to clear evidence that intensive blood pressure control significantly reduced the risk of cardiovascular disease and mortality.
However, researchers continued to analyze the data for the MIND portion of the study, which focused on dementia risk.
Their findings indicated that intensive blood pressure control did not reduce the risk of dementia but did have a notable impact on lowering the risk of MCI.
Exploring the Relationship with Diastolic Blood Pressure and Cerebral Blood Flow
The recent research delved deeper into the connection between intensive blood pressure control and dementia risk, with a particular focus on whether intensive control could be detrimental to cognitive function in individuals with very low diastolic blood pressure.
It also examined whether intensive control affected blood flow to the brain, a condition associated with accelerated cognitive decline and a higher risk of dementia.
Cerebral blood flow was measured using magnetic resonance imaging in a subset of participants.
Key Findings
The study included a total of 8,563 participants. The analysis revealed several key findings:
Diastolic Blood Pressure and Cognitive Decline: Individuals with the lowest diastolic blood pressure levels experienced a higher rate of cognitive decline compared to those with higher diastolic pressure levels.
Intensive Blood Pressure Control and Cognitive Health: Irrespective of diastolic pressure levels, individuals in the intensive blood pressure control group had lower rates of probable dementia or mild cognitive impairment compared to those in the standard control group.
No Evidence of Harm to Cerebral Blood Flow: Importantly, there was no evidence that intensive blood pressure control adversely affected cerebral blood flow.
Discussion and Limitations
Dr. Gottesman underscores the potential cognitive benefits of intensive blood pressure control, particularly for individuals with very high diastolic pressure levels.
However, she emphasizes caution in interpreting these findings, acknowledging that individuals with very low diastolic pressure are different from those with higher levels.
Those with lower diastolic pressure were more likely to be older and have more health problems.
Additionally, some individuals with dementia may already experience a drop in blood pressure, which could explain the lack of benefit observed in the very low diastolic group.
One limitation of the study is its relatively short follow-up period, as the SPRINT trial was halted prematurely.
Longer-term data may provide a more comprehensive understanding of the safety and effectiveness of intensive blood pressure control in these populations.
In conclusion, this study contributes valuable insights into the relationship between intensive blood pressure control and cognitive health.
It suggests that intensive control may reduce the risk of cognitive decline, including mild cognitive impairment, in individuals with high systolic blood pressure, regardless of their diastolic levels.
However, further research and long-term studies are needed to confirm these findings and provide a more nuanced understanding of the potential benefits and risks associated with intensive blood pressure management in various patient groups.
If you care about high blood pressure, please read studies that early time-restricted eating could help improve blood pressure, and coconut sugar could help reduce blood pressure and artery stiffness.
For more information about blood pressure, please see recent studies about added sugar in your diet linked to higher blood pressure, and results showing vitamin D could improve blood pressure in people with diabetes.
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