Lower target for blood pressure control linked to better cognition

1. In this prospective observational study of patients being treated for hypertension, lower systolic blood pressures were associated with slower cognitive decline.

2. The magnitude of difference between high and low blood pressure levels was greater for self-identified black patients than for white.

Evidence Rating Level: 2 (Good)       

Study Rundown: Despite demonstration of superior cardiovascular outcomes for more aggressive blood pressure control, adoption of the Systolic Blood Pressure Intervention Trial (SPRINT) results into clinical practice has been met with concern for potential adverse effects. In particular, for older patients there has been concern that more aggressive blood pressure management may be associated with falls and more rapid cognitive decline. The eighth Joint National Committee (JNC-8) hypertension guidelines recommend a systolic blood pressure (SBP) target of 150 mmHg. The current study sought to evaluate the effect of blood pressure level in older patients treated for hypertension on cognitive decline. The study demonstrated that lower SBP levels was associated with a slower decline in cognitive function. The difference in cognitive decline between high and low blood pressure levels was more pronounced for black patients, who may be a particular risk of hypertensive related morbidity.

The study adds more evidence for the benefit of more aggressive hypertension control. The study was relatively large, followed a prospective cohort over a long time-period, and included a large proportion of black patients who are otherwise underrepresented in other studies. The main limitations of the study included biases introduced by the observation design, including the fact that patients in the low blood pressure levels were ones that could tolerate the therapy. The exact classes of antihypertensive medications also varied according to clinician preference.

Click to read the study, published in JAMA Neurology

Relevant Reading: Impact of Hypertension on Cognitive Function: A Scientific Statement From the American Heart Association

In-Depth [prospective cohort]: This study consisted of participants in the Health Aging and Body Composition (Health ABC) study of well-functioning adults 70-79 years of age who have been followed for 10 years (1997-2007). The study only analyzed patients who were being treated for hypertension and were cognitively intact at baseline. The Digit Symbol Substitution Test (DSST) and the Modified Mini-Mental State Examination (3MSE) were used to evaluate cognitive function at years 1, 3, 5, 8, and 10.

Of the 1657 individuals included in the study 18.5% has blood pressures lower than 120 mmHg, 37.8% with pressures lower than 140 mmHg, 15.9% between 140 and 150 mmHg, and 57.7% with blood pressure greater than 150 mmHg. All SBP levels experienced cognitive decline, but the decline was greatest for the >150 mmHg group, and least for the <120 mmHg participants. There was a greater effect of blood pressure for black patients compared to white patients (p = 0.03 for racial difference).

Image: PD

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