"An experimental Alzheimers disease drug gantenerumab may help lower levels of amyloid plaque in the brains of people with the disease an early clinical trial indicates. The new study which appears online Oct.  in the Archives of Neurology is among the first to show the effects of an antiamyloid drug in humans with Alzheimers disease but experts caution that while promising more research is needed before this drug can be deemed safe or effective. And in what may turn out to be an equally important caveat experts also say that its by no means certain that reducing levels of amyloid plaque would stave off memory loss and the other mental declines associated with the disease because the role of the plaque in Alzheimers isnt fully understood. Alzheimers disease is the most common form of dementia. Symptoms including serious memory loss confusion and mood changes develop gradually and worsen with time. Recently many strides have been made in diagnosing Alzheimers disease earlier but doctors have been stymied by a lack of effective treatments to stop or slow the course of the disease. Its long been known that a protein fragment called betaamyloid builds up in the spaces between nerve cells in the brains of people with Alzheimers disease. The new drug gantenerumab targets these amyloid proteins by priming the bodys immune system to recognize them as invaders. Of  people with mildtomoderate Alzheimers disease those who received two to seven infusions of the experimental drug every four weeks showed marked reductions in the amount of plaque in their brains via imaging tests that were conducted several months after their treatments. By contrast amyloid load increased among people who were randomized to receive the placebo. The new drug was given at either  or  milligrams mg doses. The higher dose yielded greater reductions in amyloid levels the study showed. People who were given the  mg doses saw a nearly  percent reduction in the amount of amyloid and those given the  mg doses saw a  percent reduction. The new study was conducted and funded by the drugs manufacturer F. HoffmannLaRoche Ltd. in Basel Switzerland. The big question is whether or not reducing amyloid levels has any effect on the symptoms or progression of Alzheimers disease said Dr. Patrick Lyden chief of neurology at CedarsSinai Medical Center in Los Angeles. There is a growing concern that amyloid is a guilty bystander but not the actual culprit in the brains of people with Alzheimers disease and taking away the bystander may not help the patient he said. There are approximately one dozen therapies including vaccines for Alzheimers disease that are currently in the pipeline Lyden noted. They are all extremely exciting and promising in animals he said. This is the first one to show a preliminary result in people but we have a huge way to go to make sure it is safe and improves symptoms. Many in the Alzheimers research community are awaiting these drugs with bated breath but none are ready for prime time he said. The leading theory of Alzheimers disease is that an imbalance in the production or clearance of the amyloid plaque in the brain initiates a cascade of events that lead to dementia explained Dr. Neelum Aggarwal an associate professor of neurological sciences at Rush Alzheimers Disease Research Center at Rush University Medical Center in Chicago. Accumulation of the plaques cause a variety of cellular responses inflammation neuronal death and thus any potential treatment that can alter these processes would be beneficial she said. The hope is that gantenerumab or other drugs like it will not only prevent amyloid from accumulating in the brain but also slow down the cognitive impairment that occurs in people with Alzheimers disease she added. That said these experimental drugs carry the potential for serious side effects including causing the immune system to go haywire. The main issue that remains for this type of drug development is managing the immune response Aggarwal said. Other side effects include a potentially fatal fluid buildup in certain areas of the brain. This is problematic in that use of these treatments may carry a very high risk for neurologic complications thus necessitating heightened monitoring and diminishing its applicability as a treatment for a larger patient population such as the Alzheimers disease population she said.  If any of these drugs make it through the pipeline it also needs to be determined who will get them including whether the drugs will be given to prevent Alzheimers in patients at highrisk of the disease or to treat it once its started. The need for a drug to delay the onset or slow progression of Alzheimers disease cant be underestimated Aggrawal said. In the United States alone there are . million people with Alzheimers disease and the numbers are expected to increase to  million by  when approximately three of every five people over the age of  will have Alzheimers disease she said. More information For more information about Alzheimers disease signs symptoms and treatments visit the Alzheimers Association http SOURCES Neelum Aggarwal M.D. associate professor neurological sciences Rush Alzheimers Disease Research Center Rush University Medical Center Chicago Patrick Lyden chief neurology CedarsSinai Medical Center Los Angeles Oct.   Archives of Neurology online"