June 20, 2005
Alzheimer's disease, the mind-robbing illness that affects some 4.5 million Americans, may be due in some cases to a defect in the immune system, a new study reports. The finding, reported in the June 10 issue of the Journal of Alzheimer's Disease, requires additional research but could one day lead to new ways to diagnose and treat the disease.
Medical researchers from the University of California, Los Angeles discovered that some people with Alzheimer's have an immune system problem that makes it difficult for them to clean away a waste product in the brain called beta-amyloid. Beta-amyloid is a toxic substance that, in excess, leads to the formation of plaques in the brain, a hallmark of Alzheimer's disease. As plaque builds up, healthy brain cells die, leading to the characteristic memory loss and personality changes of Alzheimer's.
Using blood samples, the investigators found that in healthy people, immune system cells called macrophages helped to prevent the buildup of beta-amyloid waste products. In contrast, the researchers found that macrophages from some people with Alzheimer's disease could not adequately perform this cleaning job.
"Macrophages are the janitors of the innate immune system, gobbling up waste products in the brain and throughout the body," says study leader Dr. Milan Fiala of UCLA. "If further study shows that this defective macrophage function is present in most Alzheimer's disease patients, new hormonal or immune-boosting approaches may offer ways to treat the disease."
Researchers are currently planning additional studies to find out how the immune system affects the development of Alzheimer's disease. They plan to test various hormones, such as insulin-like growth factor I, and inflammation-fighting natural substances, such as curcumin (found in curry powder) to see if these substances alter immune function and plaque buildup. Better understanding of the way the immune system affects Alzheimer's could also lead to tests that diagnose the disease at an early stage, before symptoms become prominent and when treatments may be more effective.
Basic scientific research is vital for unraveling the underlying causes of Alzheimer's disease. Only then can scientists develop effective therapies that target disease-causing defects in the brain. Research sponsored by organizations like the Fisher Center for Alzheimer's Research Foundation is critical for funding studies that may one day lead to effective new treatments for the disease.
Dr. Milan Fiala, Dr. John Ringman, UCLA Department of Neurology, and Dr. Francesco Chiappelli, UCLA Department of Oral Biology and Medicine. Journal of Alzheimer's Disease, June 10, 2005.