Reduction of blood pressure could reduce the risk of dementia for patients aged 80 years or more, according to research released on July 8, 2008 in The Lancet Neurology.
The Hypertension in the Very Elderly Trial (HYVET) was established to observe the benefits and risks of hypertension in the very elderly, and includes several subdivisions in various areas of health and development. The dementia sub-study of HYVET, known as HYVET-COG, examines previous research in terms of cognitive functioning over the course of the study. When combined with the results from other placebo controlled trials, researchers found that a 13% reduction in dementia is associated with antihypertensive treatment.
Lead author Dr Ruth Peters of the Division of Medicine, Imperial College London indicates that this is in addition to other benefits related to antihypertensive treatment: “The results from HYVET-COG suggest a possible additional benefit associated with antihypertensive treatment in addition to the cardiovascular benefits as already demonstrated in this very elderly group.”
Hypertension in the study was defined as a systolic blood pressure (SBP) 160-200 mm Hg and diastolic pressure (DBP) less than 110 mm Hg. Patients with hypertension over the age of 80 were enrolled in a double-blind, placebo-controlled trial. Subjects were randomly assigned to receive 1.5 mg sustained release indapamide (with the option of an additional 2-4 mg perindopril) or a placebo. Patients targeted an SBP of 150 mm Hg and DBP of 80 mm Hg.
At the start of the trial, no participants had a clinical diagnosis of dementia, and cognitive function was assessed annually using the standard mini-mental state examination (MMSE). A drop of this score to below 24 total points or a drop by more than three points in one year were considered potential cases of dementia, and were evaluated using standard diagnostic criteria and expert review.
The trial was discontinued in 2007 at the second yearly analysis, before its planned completion, because the decrease in death and stroke rates for medicated subjects was so significant that it was considered unethical to continue the trial when potentially life-saving treatment was not being provided to all patients.
A total 3,336 of the HYVET participants completed at least one follow up assessment, and the population had a mean follow-up assessment of 2.2 years. Of the total, 1,687 were administered the medication while 1,649 were given the placebo. AHT decreased the SBP by an additional 15.0 mm Hg and DBP by an additional 5.9 mm Hg over the placebo group. In comparison, the rate of dementia in the placebo group was 38 per 1,000 patient-years and in the test group was 33 per 1,000 patient-years. This difference was not significantly significant, but, when this was combined with a meta-analysis with the other placebo controlled trials, the results showed that the treatment reduced dementia incidence by 13%.
Many potential reasons for the non-significant findings of decreased dementia in the HYVET-COG study itself, including the short follow-up time, and the comparatively short period of the trial. The authors also point out the modest improvement shown by the test subjects. In conclusion, they state that this association has great potential to be practically and statistically significant. “The HYVET results provide some support for the treatment of very elderly people with hypertension to reduce incident dementia…The meta-analysis of HYVET and three similar trials showed that the reduction in the risk of dementia associated with lowering blood pressure might be clinically significant.”
Dr Ingmar Skoog, Institute of Neurosciences, Sahlgrenska Academy at Goteburg University, Sweden, contributed an accompanying Comment which states that this treatment is significant irregardless of this potentially important finding. “What are the clinical implications of these findings? The HYVET investigators show that short term antihypertensive treatment is beneficial for stroke and total mortality among the very elderly; therefore detection and treatment of hypertension in elderly people, irrespective of whether it prevents dementia, is important because it might prevent cardiovascular disease.”
Incident dementia and blood pressure lowering in the Hypertension in the Very Elderly Trial cognitive function assessment (HYVET-COG): a double-blind, placebo controlled trial
Ruth Peters, Nigel Beckett, Francoise Forette, Jaakko Tuomilehto, Robert Clarke, Craig Ritchie, Adam Waldman, Ivan Walton, Ruth Poulter, Shuping Ma, Marius Comsa, Lisa Burch, Astrid Fletcher, Christopher Bulpitt, for the HYVET investigators
Lancet Neurology, July 8, 2008
DOI:10.1016/S1474- 4422(08)70143-1
Antihypertensive treatment and dementia prevention
Ingmar Skoog
Lancet Neurology, July 8, 2008
DOI:10.1016/S1474-4422(08)70142-X
Written by Anna Sophia McKenney