Twelve-million people around the world suffer from Alzheimer's disease. People with the disease slowly lose their ability to remember and think. These changes are caused by the progressive death of brain cells. About ten percent of sixty-five-year-old people have the disease. However, the risk of the disease increases with age.
No one knows what causes Alzheimer's. Scientists know that the brains of patients contain unusual groups of proteins where nerve cells should be. These proteins are called amyloid plaques. They are believed to cause nerve cells to die. However, scientists are not sure if amyloid plaques cause Alzheimer's disease or are a result of the disease.Last year, scientists from the Elan Pharmaceutical Company in San Francisco, California reported progress against the disease. They said a new vaccine medicine prevented the formation of plaques in young mice.
The scientists said the vaccine also reduced the size of already established plaques in the mice's brains. Recently, they showed that the vaccine does not harm mice or people. More tests are planned to see if the vaccine can destroy the amyloid plaques, and what effect that will have on Alzheimer's disease.Scientists are studying other ways to block the body's production of beta amyloid proteins. Everyone produces beta amyloid throughout their bodies. People who get Alzheimer's disease at an early age produce proteins that are likely to stick together. The researchers hope to stop the production of an enzyme that aids in amyloid production. It is called gamma secretase. They believe this will lower the amount of amyloid so that no new plaques will form.Earlier this year, scientists injected a few healthy people with a substance they believe could stop the production of gamma secretase. However, scientists do not know the exact purpose of gamma secretase in the body. Some evidence suggests it is important to the development of blood cells. So researchers are trying to see if reducing the enzyme will slow the Alzheimer's but not harm the patients.
Scientists know that gamma secretase helps cause Alzheimer's in younger people who develop the disease. But it is not clear if it is linked to the disease in older patients. Some scientists say people over the age of sixty-five do not get Alzheimer's because their bodies produce too much amyloid protein. They get the disease because their bodies cannot destroy the proteins that are produced.Scientists at the University of California at Los Angeles recently carried out a study testing a common drug in mice. The study suggests that the common drug ibuprofen may reduce abnormal amounts of beta amyloid. Ibuprofen is a nonsteroidal anti-inflammatory drug that people take to reduce the pain of arthritis and other conditions. The new study supports about twenty earlier studies. They have shown that people who took ibuprofen and similar drugs had a lower risk of developing Alzheimer's disease than people who did not take the drugs.
((MUSIC BRIDGE))Researchers also are developing drugs to treat severe Alzheimer's in older people. One of the drugs is called memantine. Memantine already is being used in Germany to treat similar brain problems. Recently researchers at New York University reported the results of a study about the drug. It involved about two-hundred-fifty patients at thirty medical centers in the United States. Scientists said memantine slowed the progress of Alzheimer's disease and did not appear to cause bad effects. It is one of the few studies to show good effects in people with severe Alzheimer's disease.Another possible drug to treat Alzheimer's is neotrophin. It appears to increase nerve growth in the brain. The latest study shows the drug can help improve thinking in people with severe Alzheimer's. Nearly four-hundred people were divided into two groups. One group took an inactive substance for ninety days. The other group took neotrophin. Patients receiving the neotrophin showed improvement after twenty-eight days. The researchers want to test the drug for longer periods of time. They are planning a six-month international test that will involve one-thousand-five-hundred patients.
((MUSIC BRIDGE))Other researchers say the cause of Alzheimer's may be fibers that stick together inside nerve cells. Scientists at the New York State Institute for Basic Research found increased amounts of the chemical element phosphorous in the nerve cell fibers of Alzheimer's patients. The researchers said they were able to make normal fibers stick together by changing the enzyme that controls phosphorous. This could lead to development of a medicine that could prevent the increase of phosphorus in the brain.Still other researchers are studying foods and the development of Alzheimer's disease. In Nineteen-Ninety, researchers at the Erasmus Medical Center in Rotterdam, The Netherlands began a study. They collected information about the foods eaten by more than five-thousand healthy people. All the people were between the ages of fifty-five and one-hundred-six. The researchers wanted to know the effects of substances called antioxidants that are present in some foods.Antioxidants include vitamins C and E and beta-carotene. Antioxidants block tissue damage in the body caused by chemicals called oxygen free radicals.
The Dutch researchers found that people who ate more foods containing antioxidants had a lower risk of developing Alzheimer's than those who ate fewer amounts. Vitamins C and E were linked to a nearly twenty percent lower risk of Alzheimer's. So were large amounts of fruits and vegetables.
((MUSIC BRIDGE))Other Researchers are trying to find ways to tell if a person is suffering normal memory loss, or early signs of Alzheimer's disease. The first signs of the disease can appear ten years or more before doctors can recognize the problem as Alzheimer's. It is normal for a person to forget things. But memory loss from early Alzheimer's disease is more serious. It affects a person's ability to work. And it causes problems with language and judgment.A condition known as Mild Cognitive Impairment, or MCI, is worse than normal forgetfulness but not as serious as Alzheimer's disease. People with MCI have trouble remembering things they see.
Twelve percent of people with MCI develop Alzheimer's disease every year. This is compared with only one or two percent of normal older people who develop Alzheimer's each year. Researchers say one difference seems to be the size of a part of the brain called the hippocampus. It is the area that is important for learning and memory.People with a normal sized hippocampus seem to develop memory problems slowly. People with MCI whose hippocampus has already begun to shrink develop severe memory problems faster. Researchers also say that decreased activity in the hippocampus area of the brain may show which people may lose their memory abilities faster.
Five studies involving four-thousand patients are now being done around the world. They involve people with Mild Cognitive Impairment. Researchers are trying to find out if early use of Alzheimer's drugs or substances such as Vitamin E can prevent or slow progress toward Alzheimer's disease.Medical experts say more than twenty-two-million people around the world will have Alzheimer's disease in twenty-five years. The number of people with the disease is expected to increase to forty-five-million in fifty years. Medical experts say it is important to find an effective treatment for Alzheimer's or a way to prevent the disease.
This SCIENCE IN THE NEWS program was written by Nancy Steinbach. This is Bob Doughty.And this is Steve Ember. Join us again next week for more news about science in Special English on the Voice of America.