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.
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.
FACTOID: As many as 4.5 million Americans suffer from Alzheimer's disease. It usually sets in after age 60, and the risk increases with age, although it is not a normal part of the aging process. While only about 5 percent of men and women aged 65-74 have the disease, nearly half of those 85 or older may have it.
The Optical Society of America contributed to the information contained in the TV portion of this report.