Alzheimer’s disease is a chronic, slowly progressive, gradual in onset, irreversible condition that destroys brain nerve cells and other structures in the central nervous system. People with Alzheimer’s disease slowly develop dementia—a loss of memory and intellectual and social skills that result in confusion, disorientation, and the inability to think, reason, and understand. The decline in cognition and memory results in activities of daily living to be performed with increasing difficulty.
People with Alzheimer’s disease (and other dementias) have symptoms that can change from day to day. There seem to be occasional times when improvement may be noticed, but over time the disease progressively worsens. The most common symptoms is memory loss.
It has been estimated that over 4 million Americans have Alzheimer’s disease and the total healthcare costs are estimated to be over $100 billion in the US alone. The number of patients with Alzheimer’s disease is expected to triple during the next 20 years as the baby boomer generation ages with an associated rise in the economic burden.
Scientists know that Alzheimer’s disease is caused by damage to brain nerve cells, as well as a loss of certain chemicals that facilitate communication between nerve cells. What is still not clearly understood is why this damage occurs.
Brain autopsies of Alzheimer's patients show 2 characteristic brain abnormalities:
- Neurofibrillary tangles—These are found inside nerve cells in the hippocampus and temporal and frontal lobes of the brain. A type of protein called tau is found within these tangles.
- Neuritic plaques—Located outside the nerve cells, the plaques are surrounded by dying neurons (nerve cells) and contain a sticky protein called beta amyloid. The presence of the plaque seems to be linked to reduction of an important chemical called acetylcholine. Acetylcholine helps neurons relay messages in the brain and is essential for memory and learning.
- Reviewer: Rimas Lukas, MD
- Review Date: 09/2016 -
- Update Date: 09/17/2014 -