Detecting Alzheimer's Early - Inside Science
2005
BACKGROUND: Researchers at Harvard Medical School have developed two optical tests that could potentially diagnose Alzheimer's disease in its beginning stages. The tests build upon a recent discovery that the presence of telltale proteins in the eye is an early sign of the disease. Such tests can improve patients' chances to start treatment earlier, and may also speed development of new drugs.
HOW IT WORKS: The same type of amyloid beta proteins which are a hallmark of Alzheimer's when found in the brain are also found in the lens and fluid of the eye. These proteins produce an unusual type of cataract in a different part of the eye than common cataracts (which are not associated with Alzheimer's). Scientists can detect these proteins by injecting a light-sensitive dye, then shining a laser onto the specific part of the lens where the cataracts tend to form. The molecules in the dye bind to the protein molecules, if they are present, and the light will cause the resulting molecules to glow. This technique is called quasi-elastic light scattering.
ABOUT ALZHEIMER'S: Alzheimer's is the most common form of dementia, a brain disorder that primarily affects the elderly. Scientists still aren't sure what causes the disease, and there is no cure. It is named after a German doctor, Alois Alzheimer, who noticed (in 1906) anomalies in the brain tissue of a woman who had died of a strange mental illness. There were abnormal clumps (called amyloid plaques) and tangled bundles of fibers, both of which are the most common signs of Alzheimer's. Other brain changes can occur. Nerve cells die in areas of the brain vital to memory and other mental abilities, and the connections between nerve cells are disrupted, impairing thinking and memory.
SYMPTOMS: Alzheimer's is a slow-moving disease, and in its earliest stages, may merely appear to be mild forgetfulness, and confused with age-related memory change. There may be problems remembering recent events or activities, or the names of familiar people or objects. As the disease progresses, the forgetfulness becomes more severe, interfering with daily activities, such as brushing one's teeth. There are problems speaking, understanding, reading or writing, and eventually the brain damage becomes so severe as to require total care.