Over 5 million Americans have Alzheimer’s disease (AD), the major cause of dementia in the United States. The national cost of caring for the AD population is estimated at over $200 billion for 2012, according to the Alzheimer’s Association and the National Institute on Aging. The average lifetime cost of care for an individual with AD is $174,000 (www.alz.org).
AD is a neurological disorder characterized by slow and progressive impairment of cognitive function. The most common form of AD is age-related, with an onset of approximately age 60. Early onset AD is a genetically transmitted disease that begins before age 60.
Both forms of AD are characterized by the same symptoms including memory loss, forgetfulness, untidiness, confusion, restlessness, lethargy, and deficiency in decision making. These symptoms are followed by a second stage in which patients lose interest in their surroundings and often are confined to a wheelchair or a bed. The final stage includes emptiness of the mind, the loss of control of all body functions, and severe brain damage leading to death. As these symptoms and signs are often subtle in the initial phase of the disease, patients are usually significantly impaired by the time a diagnosis is made.
The cause of AD is unknown, but hallmark physical change in the AD brain is the abnormal formation of amyloid plaques and neurofibrillary tangles. These protein deposits occur with normal aging, but the extensive degree to which they are found in the AD brain points to a potential defect in how the body processes these proteins as a causative factor in AD. The abnormal protein deposits collectively decrease the production of neurotransmitters in the brain, leaving the brain unable to send electrical signals. As a result, critical brain and body functions are hindered. No cure has been found, but extensive research is ongoing to understand and develop treatments for AD.
Recently it has become apparent to health scientists that people with diabetes have an increased risk of developing AD. According to some study results, people with type 2 diabetes are twice as likely to develop AD. Given the epidemic growth of the U.S. diabetes population, an associated significant increase in AD is expected.
High glucose levels in diabetic patients are associated with impaired cognitive performance in individuals with type 1 and type 2 diabetes. A recent study of the Mayo Clinic AD Patient Registry reveals that 80 percent of AD patients have either type 2 diabetes or impaired fasting glucose levels. Some metabolic syndrome disorders, which occur together and increase the risk of diabetes, coronary artery disease and stroke, also are risk factors for AD. This link has led researchers to search for the mechanism underlying diabetes-related AD progression.