Low BP Might Speed Mental Decline in Dementia

June 27, 2017

Antihypertensive regimens that perhaps work a little too well were linked to faster cognitive decline among older adults with pre-existing dementia or mild cognitive impairment (MCI) in a cohort study.

Patients in the lowest tertile of daytime systolic blood pressure (128 mmHg or less) showed a greater decline in Mini-Mental State Examination (MMSE) score over a median 9 months than those in the middle tertile (129 to 144 mmHg) or those in the top tertile of 145 mmHg or higher -- mean -2.8 points on the 30-point MMSE scale versus -0.7 in both higher groups (P=0.002 and P=0.003, respectively).

The results suggested "that strict control of systolic blood pressure may negatively affect cognition, with daytime systolic blood pressures of 130 to 145 mmHg being the most appropriate therapeutic targets," Enrico Mossello, MD, PhD, of the University of Florence, Italy, and colleagues found.

The associations were significant only among individuals on antihypertensives and were independent of age, vascular comorbidity score, and baseline cognitive level, the group reported online in JAMA Internal Medicine.

The lower blood pressure ranges were also not associated with better health-related outcomes in this cohort of 172 people ages 65 and older (mean 79) attending two memory clinics in Italy that offered 24-hour ambulatory blood pressure monitoring regardless of baseline hypertension diagnosis.

Among participants, 68.0% had dementia and 32.0% had MCI. About 70% were being treated with antihypertensive medications.

Prior evidence has been mixed, Behnam Sabayan, MD, PhD, and Rudi G. J.Westendorp, MD, PhD, both of Leiden University Medical Center in the Netherlands, noted in an accompanying editorial.

"The link between blood pressure and cognitive impairment is a complex beast," they wrote.

"Given the observational design, it cannot be concluded that antihypertensive therapy is directly responsible for the link between low daily systolic blood pressure and cognitive decline," they cautioned.

"It is likely that individuals receiving antihypertensive therapy had higher loads of overt and covert cardiovascular pathologies, which could independently lead to accelerated cognitive decline," they added.

While randomized clinical trials are needed to address confounding by indication, it may be time to move from a "one-size-fits all" approach to one individualized by age, hemodynamics, and degree of systemic and cerebrovascular damage, Sabayan and Westendorp suggested.

Guidelines have tussled over antihypertensive treatment of seniors overall.

The American Heart Association/American College of Cardiology recommendations urge physicians to stick with the Seventh Joint National Committee (JNC7) thresholds of 140/90 mmHg.

A controversial 2014 report from some members of a panel appointed to update those recommendations (commonly but unofficially known as JNC8) called on physicians to loosen the treatment goal to 150/90 mmHg for people ages 60 and older without diabetes or chronic kidney disease.

No guidelines have specifically addressed older adults with cognitive impairment or dementia.

One study of elderly nursing home residents showed no prognostic effect of blood pressure, which "raised doubts regarding the clinical meaning of office blood pressure in cognitively impaired older adults," Mossello's group noted.

That study also showed a poor correlation between in-office blood pressure and ambulatory measurements, which appeared to be true in the memory clinic cohort as well.

Office blood pressures had a weaker association with MMSE score change. Other ambulatory blood pressure monitoring variables, such as nighttime systolic or diastolic pressure and dipping, were not associated with MMSE score change.

"Owing to its greater simplicity, office blood pressure measurement should be the first step, although we advise routine use of ambulatory blood pressure monitoring before starting or upgrading antihypertensive treatment in this frail population if office systolic blood pressure is elevated," Mossello's group suggested.

That agreed with recent draft recommendations from the U.S. Preventive Services Task Force.

Limitations of the study included its small sample size, short follow-up period, and "the setting of an outpatient memory clinic,which does not allow direct generalization of results to primary or acute care," they noted.

Reposted from Medpage Today

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