The Alzheimer's Association notes that 5.3 million people have Alzheimer's disease, a neurodegenerative disease. Patients with Alzheimer's disease have problems with cognitive functions. For example, patients can have memory loss, difficulty with abstract thinking and judgment, and problems with language, such as difficulty reading or writing. Alzheimer's disease patients have changes in personality and problems caring for themselves during the advanced stages of the disorder. Emotional changes may also occur, such as depression or agitation.
MedlinePlus, a service of the US National Library of Medicine (NLM) and the National Institutes of Health (NIH), explains that three common changes occur to the brain from Alzheimer's disease: senile plaques, neuritic plaques and neurofibrillary tangles. Doctors can examine these changes to the brain after the patients dies. With the plaques, clusters of dying nerve cells form around protein. With the tangles, protein become entangled within the nerve cells. The protein in question with the plaques is called beta-amyloid (or amyloid beta). In a new study published in the May 20, 2010 issue of PLoS One, the authors found that beta-amyloid protein also build up in Down syndrome patients, but in their eyes.
Down syndrome, a genetic disorder, results from an extra chromosome. If a patient has an extra chromosome 21, she has a type of Down syndrome called Trisomy 21. Down syndrome causes physical changes, such as small ears and mouth, flattened nose, upward slanting eyes and decreased muscle tone. Patients with Down syndrome can have cognitive and behavioral problems. Examples include slow learning, poor judgment, short attention span and impulsive behavior.
MedlinePlus notes that patients with Down syndrome may show signs of Alzheimer's disease, which the authors of the study add is seen by age 30. The build up of beta-amyloid in Down syndrome patients results in cataracts, an eye condition that results in cloudy vision. The authors point out that beta-amyloid accumulation can start during childhood. These cataracts also occur with advanced Alzheimer's disease. The authors explain that Down syndrome patients have another copy of an Alzheimer's disease gene, which leads to the beta-amyloid protein build up. HealthDay News reports that the authors are working on a scanner to measure the amount of protein in the lens, which may lead to early detection of Alzheimer's disease.