A low level of “good” cholesterol is a well-known risk factor for heart disease. A new study by investigators at Columbia University College of Physicians & Surgeons now suggests that a low level of good cholesterol may also raise the risk of developing Alzheimer's disease.
“Low levels of 'good' cholesterol (a.k.a. high-density lipoproteins or HDL) are very common in the United States,” says the study's lead author, Christiane Reitz, MD, PhD, assistant professor of neurology (in the Sergievsky Center and Taub Institute). “If raising HDL can lower a person's risk of developing Alzheimer's disease, that means we may be able to significantly reduce the rate of Alzheimer's disease in the population,” Reitz says, though she cautions that the finding still must be confirmed in other studies.
The study, which appears in the December issue of Archives of Neurology, is co-authored with Jose Luchsinger, MD, MPH, associate professor of medicine and epidemiology, and Richard Mayeux, MD, director of the Gertrude Sergievsky Center and Sergievsky Professor of Neurology, Psychiatry, and Epidemiology.
Previously, the relationship between HDL and Alzheimer's disease had been unclear. Some studies found an association, but others, including one of Reitz's own, found no connection. The new study, Reitz says, follows subjects for a longer period of time than previous studies, resulting in a more accurate account of the number of subjects who ultimately develop Alzheimer's.
After monitoring 1130 elderly residents of northern Manhattan for an average of four years, the researchers found a 40 percent higher incidence of Alzheimer's in residents with low HDL (less than 55 mg/dl). The reason that low HDL is associated with a higher rate of Alzheimer's isn't understood. One possibility is that it works through stroke. “We know low HDL raises the risk of stroke and that stroke is associated with Alzheimer's, so stroke may be the mediator,” Reitz says. “But there's also evidence that HDL works by itself to clear amyloid proteins [the proteins believed to cause Alzheimer's] from the brain.”
Because the study included a large number of African Americans and Hispanics, unlike previous studies that focused on whites, the finding may indicate that low HDL is linked to a high risk of Alzheimer's in many different ethnicities.
The study, to be published in the journal Pain, found that particular areas of the brain were less active as meditators anticipated pain, as induced by a laser device. Those with longer meditation experience (up to 35 years) showed the least anticipation of the laser pain.
Dr Brown, who is based in the University's School of Translational Medicine, found that people who meditate also showed unusual activity during anticipation of pain in part of the prefrontal cortex, a brain region known to be involved in controlling attention and thought processes when potential threats are perceived.
He said: “The results of the study confirm how we suspected meditation might affect the brain. Meditation trains the brain to be more present-focused and therefore to spend less time anticipating future negative events. This may be why meditation is effective at reducing the recurrence of depression, which makes chronic pain considerably worse.”
Dr Brown said the findings should encourage further research into how the brain is changed by meditation practice. He said: “Although we found that meditators anticipate pain less and find pain less unpleasant, it's not clear precisely how meditation changes brain function over time to produce these effects.
“However, the importance of developing new treatments for chronic pain is clear: 40% of people who suffer from chronic pain report inadequate management of their pain problem.”
In the UK, more than 10 million adults consult their GP each year with arthritis and related conditions. The estimated annual direct cost of these conditions to health and social services is £5.7 billion.
Study co-author Professor Anthony Jones said: “One might argue that if a therapy works, then why should we care how it works? But it may be surprising to learn that the mechanisms of action of many current therapies are largely unknown, a fact that hinders the development of new treatments. Understanding how meditation works would help improve this method of treatment and help in the development of new therapies.
“There may also be some types of patient with chronic pain who benefit more from meditation-based therapies than others. If we can find out the mechanism of action of meditation for reducing pain, we may be able to screen patients in the future for deficiencies in that mechanism, allowing us to target the treatment to those people.
The Partnership for Healthy Weight Management (including the American Dietetic Association) have released an easy-to-use booklet that provides information and checklists for evaluating weight loss programs and helps consumers to choose a safe and effective weight loss method.
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