Alzheimer’s Disease Background

Alzheimer’s disease (AD) is an intractable, chronic and progressively incapacitating disease characterized by the degeneration and death of several types of neurons in certain regions of the brain.  Patients affected by the disease initially suffer loss of memory, then a decline of intellectual abilities severe enough to interfere with work and activities of daily living, followed by severe dementia and, finally, death.  Currently it is estimated that over five million people in the U.S., and almost 30 million worldwide, have Alzheimer’s disease and the national cost of caring for people with Alzheimer’s is estimated to exceed $148 billion annually.  By 2050, it is estimated that 16 million people in the U.S. will have Alzheimer’s, and the global prevalence of Alzheimer’s is expected to be greater than 100 million.  AD is the third leading cause of death behind cardiovascular disease and cancer. While the disease is most common in the elderly, affecting nearly 10% of people age 65 and older and up to 50% of people age 85 and older, it has been diagnosed in patients in their 40’s and 50’s.

Alzheimer’s disease was first described in 1907 by Dr. Alois Alzheimer, a German psychiatrist who discovered large numbers of unusual microscopic deposits in the brain of a demented patient upon autopsy.  These deposits, called amyloid plaques and neurofibrillary tangles, are highly insoluble protein aggregates that form in the brains of AD patients in particular regions, including those involved with memory and cognition.  Generally, amyloid plaque is deposited on the surface of neurons, whereas neurofibrillary tangles are formed within neurons.  The plaques and tangles are associated with degeneration and loss of neurons.  The actual loss of neurons, as well as the impaired function of surviving neurons, is generally believed to be the key neuropathological contributors to the memory loss and dementia that characterizes Alzheimer’s disease.