Lower BP Linked to Cognitive Decline in Frail Elderly

Troy Brown, RN

March 13, 2019

For older patients undergoing treatment for hypertension, having a systolic blood pressure (SBP) lower than 130 mmHg is linked to additional cognitive decline, especially in those with complex health problems, new data suggest.

"Our present findings suggest the importance of close blood pressure monitoring for patients undergoing antihypertensive treatment, to maintain optimal cognition especially in those with complex health problems, those for whom we observed the strongest effect," the researchers write.

The study, by Sven Streit, MD, PhD, Institute of Primary Health Care, University of Bern, Switzerland, and colleagues, was published online March 11 in Annals of Family Medicine.

The latest guidelines from the American College of Cardiology/American Heart Association recommend keeping SBP lower than 130 mmHg for noninstitutionalized older patients.

"Hypertension trials, however, often exclude older, frail patients and those with complex health problems, and many have questioned the generalizability and applicability of the results of these studies," Streit and colleagues explain.

Therefore, the investigators analyzed data from the Integrated Systematic Care for Older Persons (ISCOPE), a population-based prospective cohort study with follow-up of 1 year, to compare cognitive decline among those undergoing hypertension treatment with SBP lower than 130 mmHg with those with SBP of 130 mmHg or higher. They evaluated changes from baseline to 1-year follow-up using several measures, including the Mini–Mental State Examination (MMSE), which assesses cognitive function; the Groningen Activity Restriction Scale (GARS), which assesses the ability to care for oneself and live independently; and the EQ-5D-3L, a quality-of-life index.

The analysis included 1266 participants whose average age was 82.4 years (standard deviation, 5 years); 874 participants (69%) were women. The researchers adjusted for age, sex, and MMSE/GARS/EQ-5D-3L scores at baseline. The investigators stratified the patients for complex health problems, which served as a proxy for frailty.

Among those receiving antihypertensive therapy (1057; 83.5%) whose SBP was lower than 130 mmHg, the crude cognitive decline on the MMSE was 0.90 points, compared with 0.14 points in participants whose SBP was higher than 150 mmHg (0.76-point less decline; P for trend, .013).

When the researchers restricted their analysis to participants with complex health problems (n = 674; 53%), the findings were similar. Compared with those with SBP lower than 130 mmHg, participants with SBP of 130 – 150 mmHg demonstrated less cognitive decline after 1 year by 0.99 points (95% confidence interval, 0.32 – 1.66 points; P = .004) on the MMSE and by 1.39 points (95% confidence interval, 0.68 - 2.11 points;P < .001) among those with SBP higher than 150 mmHg (P for trend, < .001).

By contrast, the association was not found for participants without complex health problems (P for trend, 0.35).

Participants with or without antihypertensive treatment had similar sociodemographic characteristics, but those undergoing antihypertensive treatment were more likely to have an SBP > 150 mmHg (35% vs 23%; P = .004), cardiovascular disease (48% vs 4%; P < .001), diabetes (23% vs 15%; P = .013), higher GARS score (33.3 vs 31.2; P = .019), and lower quality of life (EQ-5D-3L, 0.66 vs 0.71; P = .031).

The authors note several study strengths, including its large number of participants, inclusion of sicker patients, and extensive cognitive, functional, and quality-of-life measurement. Limitations include its observational design.

The observational design of the study precludes demonstrating causation, the authors state. "However, the strength of the associations we identified, consistency with prior studies, dose-response relation, and temporal relation of SBP measurements and outcome assessments all point toward a causal interpretation."

The authors encourage others to study the long-term safety and effectiveness of deprescribing antihypertensives to raise SBP in frail older individuals, but they say that for now, clinicians must choose the most appropriate treatment for individual patients.

"Our results suggest that SBP thresholds for treatment should be redefined, especially for frail older persons. Because older patients are more likely to be frail and experience accelerated cognitive decline, clinicians are advised to be cautious about lowering SBP too much," the researchers conclude.

The study was supported by grants from the Swiss National Science Foundation and the Gottfried and Julia Bangerter-Rhyner Foundation. The authors have disclosed no relevant financial relationships.

Ann Fam Med. Published online March 11, 2019. Full text

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