1. In this randomized controlled trial, intensive blood pressure lowering in elderly patients reduced the risk of developing Mild Cognitive Impairment (MCI) compared to standard blood pressure lowering.
2. While there was no difference in the risk of dementia between groups, the trial was terminated early due to observed cardiovascular benefits seen in the intensive blood pressure lowering group.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Vascular damage caused by high blood pressure has been shown to increase the risk and severity of dementia. However, while excessively high blood pressures are known to influence pathology, it is unclear if intensive blood pressure lowering has a beneficial or detrimental effect on dementia risk. The Systolic Blood Pressure Intervention Trial (SPRINT) was designed to evaluate the effect of lowering systolic blood pressure to less than 120mmHg on cardiovascular, renal, and cognitive outcomes. In this randomized controlled trial, elderly patients were randomized to receive either intensive blood pressure lowering (systolic blood pressure goal <120 mmHg) or standard blood pressure lowering (<140 mmHg) therapies. Though intensive blood pressure lowering did not result in a reduction in dementia diagnoses, it did reduce the risk of Mild Cognitive Impairment (MCI).
It has been hypothesized that intensive blood pressure lowering may increase the risk of dementia, this study suggests that it is unlikely to change dementia risk but may reduce the pre-dementia state of MCI. Though the study was well-designed and had a relatively large sample size, there was a drop-off in follow-up rates after about four years, and it is unclear if reduced conversion to dementia would be apparent at later time points. Finally, the trial was terminated early due to the cardiovascular benefit of better blood pressure control, which perhaps limited the observed cognitive differences.
Relevant Reading: Treatment of hypertension in patients 80 years of age or older
In-Depth [randomized controlled trial]: 9361 elderly participants were recruited to the SPRINT trial and randomized to receive either intensive (systolic blood pressure <120 mmHg) or standard (<140 mmHg) blood pressure lowering therapies for a median intervention period of 3.34 years before blood pressure management decisions were made by patient and primary care physician. Eligible patients were >50 years old and had a systolic blood pressure of 130 to 180 mmHg and were excluded if they had a diagnosis of dementia, prescribed drugs primarily used to treat dementia, diabetes, or a previous stroke. Mean age was 69.7 years, 28.2% over the age of 75, 35.6% female, 30% black, 10.5% Hispanic, mean systolic blood pressure of 139.7 mmHg, and median MOCA of 23. Mean systolic blood pressures were 121.6 mmHg (CI95 120.8 to 122.3 mmHg) in the intervention group and 134.8 mmHg in the control group (CI95 134.1 to 135.6 mmHg). While the rates of probable dementia were not reduced by intensive blood pressure lowering (Hazard Ratio 0.83; CI95 0.67 to 1.04), the rates of MCI were reduced (HR 0.81; CI95 0.69 to 0.95). A nominally significant interaction between chronic kidney disease and the intervention was realized (p = 0.04) but was not significant after correcting for multiple comparisons.
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