July 16, 2008
Getting blood pressure under control appears to be an important step for reducing heart disease and stroke in the elderly. It may also help to reduce rates of Alzheimer's and other forms of dementia, a new study suggests.
The new findings show that for those in their 80s and 90s, lowering blood pressure with antihypertensive medicines appears to be good not just for the heart and blood vessels, but for the brain as well. "The results suggest a possible additional benefit associated with antihypertensive treatment in addition to the cardiovascular benefits as already demonstrated in this very elderly group," said study author Dr. Ruth Peters of Imperial College in London.
The findings were part of the Hypertension in the Very Elderly Trial, or HYVET, an ongoing study of cognitive function in men and women age 80 and older. They were published in The Lancet Neurology, a British medical journal.
The study looked at 3,336 elderly men and women with high blood pressure, with an upper (systolic) reading of 160 to 200 mm Hg, and a lower (diastolic) reading less than 110 mm Hg. Normal blood pressure is considered to be around 120/80. All were mentally intact at the start of the trial, and participants were given annual memory tests to look for signs of Alzheimer's.
About half the study participants received one or two blood pressure drugs, indapamide and/or perindopril. The others received look-alike dummy pills. The aim was to lower their blood pressure to 150/80. After two years the study was stopped, because those taking the blood pressure medications had less likelihood of having a stroke or dying, so it was considered unethical to continue giving some patients a placebo. At that time, blood pressure had been lowered by about 15 points in the systolic reading, and about 6 points in the diastolic reading.
At the end of the relatively short study period, rates of Alzheimer's and other forms of dementia were 33 per 1,000 people in the group taking the drugs. That compared to 38 per 1,000 people in those receiving a placebo. The differences in those rates were not statistically significant, but when researchers added data from other hypertension studies in the elderly, they found that use of blood pressure drugs reduced the incidence of dementia by 13 percent.
In a commentary accompanying the study, Dr. Ingmar Skoog of Goteburg University in Sweden assessed 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," he wrote. "Therefore, detection and treatment of hypertension in elderly people, irrespective of whether it prevents dementia, is important because if might prevent cardiovascular disease."
Blood Pressure and Aging
Earlier studies have shown that blood pressure rises with age, so that many elderly people have hypertension. Rates of Alzheimer's and other forms of dementia also increase with age, affecting about half of those, 85 and older.
People who have high blood pressure in their middle years are also at increased risk for Alzheimer's and other forms of dementia in old age. Lowering blood pressure may help to reduce the likelihood of developing severe memory loss and thinking problems in old age, although studies have been conflicting.
But some doctors are reluctant to give blood pressure medicines to elderly patients, including those similar to the 80-plus-year-olds studied in the HYVET trial. They fear that lowering blood pressure too much may reduce blood flow to the brain and actually increase the likelihood of memory problems.
This study showed that the drugs may have had beneficial effects on reducing the likelihood of Alzheimer's. If the study had been allowed to continue longer, benefits may have become more apparent. The study also confirmed that blood pressure treatment is effective for lowering the risk of stroke and other life-threatening events in the very old.
Ruth Peters, Nigel Beckett, Frnacoise Forette, et al: "Incident Dementia and Blood Pressure Lowering in the Hypertension in the Very Elderly Trials Cognitive Function Asssessment (HYVET-COG): A Double-Blind, Placebo Controlled Trial." The Lancet Neurology, July 8, 2008, online edition.
Ingmar Skoog: "Antihypertensive Treatment and Dementia Prevention." The Lancet Neurology, July 8, 2008, online edition.