WEDNESDAY, April 13, 2011 (Health.com) — Treating traditional risk factors for heart disease such as hypertension, high cholesterol, and diabetes may also prevent the progression of mild memory and cognitive problems into full-blown Alzheimer's disease, a new study suggests.
Although dietary changes, cholesterol-lowering statins, and hypertension drugs such as beta-blockers are far from a surefire way to prevent Alzheimer's, these and other treatments that promote healthy blood vessels may be a practical way for people to reduce their risk, the researchers say.
The study, which was conducted in China and published in the journal Neurology, "highlights the importance of midlife vascular risk factors for Alzheimer's disease, which, unlike age and genetics, can be modified," says Whitney Wharton, PhD, a research scientist at the University of Wisconsin's Alzheimer's Institute, in Madison, who was not involved in the research.
Researchers at Daping Hospital, in Chongqing, followed 638 men and women over the age of 55 for five years. All the study participants had problems with memory and mental function that were noticeable but not severe enough to interfere with their daily functioning. This condition, known as mild cognitive impairment, progresses to Alzheimer's in roughly 10% to 15% of cases each year, according to the study.
Forty-five percent of the participants went on to develop serious dementia consistent with Alzheimer's disease. Those who had high cholesterol, hypertension, diabetes, or another heart-related risk factor were twice as likely to progress to Alzheimer's compared to people with no risk factors.
Treatment substantially reduced the risk, however. Compared to those receiving no treatment, the participants who took medication or other steps to improve their heart health were 39% less likely to convert to Alzheimer's. Those receiving treatment for just some of their risk factors were 26% less likely to develop the disease.
Researchers have long been aware of an apparent link between blood-vessel health and Alzheimer's, but this study is "the first one that shows that treating mild cognitive impairment can have results," says Anton Porsteinsson, MD, director of the Memory Disorders Clinic at the University of Rochester School of Medicine, in New York.
It's not clear why treating heart-related risk factors might lower the risk of Alzheimer's, but high blood pressure and high cholesterol may affect the accumulation of the protein plaques in the brain that are a hallmark of the disease, the authors say.
Though the results are promising, the study can't prove that treatment directly lowers Alzheimer's risk. Randomized controlled trials, which are considered the gold standard for medical research, will be needed to confirm the findings. The study will also need to be replicated in other countries.
Ian Murray, PhD, an assistant professor of neuroscience and experimental therapeutics at the Texas A&M Health Science Center College of Medicine, in College Station, says that the results would likely be the same in a non-Chinese population.
The study findings "are more than applicable," he says, "as the Western population tends to have a higher incidence of metabolic disease such as obesity and high cholesterol."