Alzheimer’s disease (AD), also referred to simply as Alzheimer’s, is a chronic neurodegenerative disease that usually starts slowly and worsens over time. It is the cause of 60% to 70% of cases of dementia. The most common early symptom is difficulty in remembering recent events (short-term memory loss). As the disease advances, symptoms can include problems with language, disorientation (including easily getting lost), mood swings, loss of motivation, not managing self care, and behavioral. As a person’s condition declines, they often withdraw from family and society. Gradually, bodily functions are lost, ultimately leading to death. Although the speed of progression can vary, the average life expectancy following diagnosis is three to nine years.
The disease is named after Dr. Alois Alzheimer. In 1906, Dr. Alzheimer noticed changes in the brain tissue of a woman who had died of an unusual mental illness. Her symptoms included memory loss, language problems, and unpredictable behavior. After she died, he examined her brain and found many abnormal clumps (now called amyloid plaques) and tangled bundles of fibers (now called neurofibrillary, or tau, tangles).These plaques and tangles in the brain are still considered some of the main features of Alzheimer’s disease. Another feature is the loss of connections between nerve cells (neurons) in the brain. Neurons transmit messages between different parts of the brain, and from the brain to muscles and organs in the body. Many other complex brain changes are thought to play a role in Alzheimer’s too.
Scientists continue to unravel the complex brain changes involved in the onset and progression of Alzheimer’s disease. It seems likely that damage to the brain starts a decade or more before memory and other cognitive problems appear. During this preclinical stage of Alzheimer’s disease, people seem to be symptom-free, but toxic changes are taking place in the brain. Abnormal deposits of proteins form amyloid plaques and tau tangles throughout the brain, and once-healthy neurons stop functioning, lose connections with other neurons, and die.This damage initially appears to take place in the hippocampus, the part of the brain essential in forming memories. As neurons die, additional parts of the brain are affected. By the final stage of Alzheimer’s, damage is widespread, and brain tissue has shrunk significantly.
Scientists don’t yet fully understand what causes Alzheimer’s disease in most people. There is a genetic component to some cases of early-onset Alzheimer’s disease. Late-onset Alzheimer’s arises from a complex series of brain changes that occur over decades. The causes probably include a combination of genetic, environmental, and lifestyle factors.
There are 7 stages of this disease. Preclinical Alzheimer’s or no impairment, Very mild impairment or normal forgetfulness, Mild impairment or decline, Mild Alzheimer’s or moderate decline, Moderate dementia or moderately severe decline, Moderately severe Alzheimer’s, Severe Alzheimer’s.
A patient with preclinical AD may appear completely normal on physical examination and mental status testing. Specific regions of the brain (eg, entorhinal cortex, hippocampus) are likely to be affected decades before any signs or symptoms appear.
The first sign of Alzheimer’s disease is usually minor memory problems. For example, this could be forgetting about recent conversations or events, and forgetting the names of places and objects. The first symptoms of Alzheimer’s vary from person to person. For many, decline in non-memory aspects of cognition, such as word-finding, vision/spatial issues, and impaired reasoning or judgment, may signal the very early stages of Alzheimer’s disease.This disease affects a person’s ability to understand, think, remember and communicate. This could impact a person’s ability to make decisions, perform simple tasks, or follow a conversation.
Scientists are conducting studies to learn more about plaques, tangles, and other biological features of Alzheimer’s disease. Advances in brain imaging techniques allow researchers to see the development and spread of abnormal amyloid and tau proteins in the living brain, as well as changes in brain structure and function. Scientists are also exploring the very earliest steps in the disease process by studying changes in the brain and body fluids that can be detected years before Alzheimer’s symptoms appear. Findings from these studies will help in understanding the causes of Alzheimer’s and make diagnosis easier.
Alzheimer’s has no current cure, but treatments for symptoms are available and research continues. Although current Alzheimer’s treatments cannot stop Alzheimer’s from progressing, they can temporarily slow the worsening of dementia symptoms and improve quality of life for those with Alzheimer’s and their caregivers. Today, there is a worldwide effort under way to find better ways to treat the disease, delay its onset, and prevent it from developing.