Excessive BP Lowering May Harm Cognitively Impaired Elderly

Marlene Busko

March 06, 2015

FLORENCE, ITALY — In a small study of older outpatients seen in a memory clinic, those who were receiving antihypertensives and had a low daytime systolic blood pressure (<128 mm Hg) had a greater 9-month decline in cognition than their peers[1].

Dr Enrico Mossello (University of Florence, Italy) and colleagues studied close to 200 patients—68% with dementia and 32% with mild cognitive impairment (MCI)—who had an average age of 79. Their findings suggest that in elderly, cognitively impaired people "strict control of systolic blood pressure may negatively affect cognition, [and] daytime systolic blood pressures of 130 to 145 mm Hg may be the most appropriate therapeutic targets," they write in an article published online March 2, 2015 in JAMA Internal Medicine.

The relationship between blood pressure and cognitive impairment "is a complex beast" and normal or low blood pressure may not supply adequate perfusion to a damaged brain, Drs Behnam Sabayan and Rudi GJ Westendorp (Leiden University Medical Center, the Netherlands) write in an accompanying invited commentary[2].

But "given the observational design [of the current study], it cannot be concluded that antihypertensive therapy is directly responsible for the link between low daily systolic blood pressure and cognitive decline," they caution. Nevertheless, "it is time to move from the concept of 'the lower the better' to the concept of 'hemodynamic optimization' to decelerate the pace of cognitive decline by a proper management of blood pressure," they write.

The researchers and editorialists call for longer, larger studies of blood-pressure control in this patient population. In a comment to heartwire , Dr Beverly Gwen Windham (MIND Center Clinic at University of Mississippi Medical Center, Jackson) who was not involved with the study, agrees.

"Meanwhile, I think it is prudent to consider each patient's life expectancy (based on age, functional status, and comorbidity), age, personal preferences regarding goals of care, and potential treatment burden; and if medications are used, follow the 'start-low-go-slow' approach typical of most geriatricians, especially in patients with cognitive impairment or frailty, and monitor for side effects," she said.

Ambulatory BP and Cognitive Changes in Dementia and MCI

There is no strong evidence to guide blood-pressure control in elderly patients with dementia and MCI, and recent European and American guidelines do not specify blood-pressure targets for these patients, Mossello and colleagues note.

They performed an observational cohort study in 172 patients (64% women) who were 65 and older, seen in two memory clinics in Italy, and diagnosed with dementia or MCI. Most patients (73.3%) had hypertension and were taking antihypertensives (69.8%).

The patients were divided into tertiles based on Holter-derived daytime systolic blood pressures (<128 mm Hg; 129 to 144 mm Hg; and >145 mm Hg) and office systolic blood pressures (<125 mm Hg; 126 to 149 mm Hg; and >150 mm Hg).

After a median follow-up of 9 months, the participants' Mini-Mental State Examination (MMSE) scores decreased from 22.1 to 20.7 (P<0.001).

The decline in MMSE scores was greater in patients in the lowest tertile of daytime systolic blood pressure (−2.8) than those in the intermediate tertile (−0.7, P=0.002) or the highest tertile (−0.7, P=0.003). Low daytime systolic blood pressure was associated with a greater cognitive decline only among participants who were receiving antihypertensives, independent of age, vascular comorbidity score, and baseline MMSE score.

Office blood pressure was not linked with worsening cognitive decline.

"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 and colleagues write.

There were no statistically significant associations between nighttime systolic or diastolic blood pressure, blood-pressure variability, or dipping and cognitive outcomes. Lower blood-pressure ranges were not linked with better health-related outcomes.

It is "challenging to treat these patients who are also some of the most vulnerable," according to Windham. Clinicians should specifically question older patients about potential adverse symptoms of overtreatment with antihypertensives (such as syncope, falls, or lack of energy), which patients may mistakenly believe are just part of normal aging.

The study was supported by the Cassa di Risparmio di Pistoia and Pescia Foundation. The authors and editorialists have no relevant financial relationships.

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