What is Alzheimer's disease?

Diana Meeks
Diana Meeks on behalf of Sigma Nursing
Family Practitioner

Alzheimer's disease (AD) is an age-related, non-reversible brain disorder that develops over a period of years. Initially, people experience memory loss and confusion, which may be mistaken for signs usually associated with normal aging. However, the symptoms of AD gradually lead to behavior and personality changes, a decline in cognitive abilities, such as decision-making and language skills, and problems recognizing family and friends. AD ultimately leads to a severe loss of mental function. This loss is related to the breakdown of the connections between certain neurons in the brain and their eventual death. AD belongs to a group of disorders called dementias, which are characterized by cognitive and behavioral problems. It is the most common cause of dementia among people age 65 and older.

Three major hallmarks in the brain are associated with the disease processes of AD:

  • Amyloid plaques: These plaques are made up of fragments of a protein called beta-amyloid peptide mixed with a collection of additional proteins, remnants of neurons and bits and pieces of other nerve cells.
  • Neurofibrillary tangles (NFTs): NFTs found inside neurons, are abnormal collections of a protein called tau. Normal tau is required for healthy neurons. However, in AD, tau clumps together. As a result, neurons fail to function normally and eventually die.
  • Loss of connections between the neurons responsible for memory and learning: Neurons cannot survive when they lose their connections to other neurons. As neurons die throughout the brain, the affected regions begin to atrophy, or shrink. By the final stage of AD, damage is widespread and brain tissue has shrunk significantly.

This answer is based on source information from the National Institute of Diabetes and Digestive and Kidney Diseases.

Alzheimer's disease, the most prevalent form of dementia, is a neurodegenerative disease. It represents up to 70 percent of dementia cases. Alzheimer's has no cure and results in death, typically within 10 years of the diagnosis.

Alzheimer's disease (AD) is the most common form of dementia, a term used to describe a group of symptoms affecting intellectual and social abilities severely enough to interfere with daily functioning.

Alzheimer's disease occurs in one in ten people over the age of 65. According to recent assessments, the rate of Alzheimer's disease is going to nearly double every 20 years. By 2050, 43 percent of those with Alzheimer's disease will need high-level care, equivalent to that of a nursing home.

Alzheimer's disease is often thought about in three stages:

  • Mild Alzheimer's disease (also called early-stage). In mild AD, the first stage, people often have some memory loss and small changes in their personality. They may have trouble remembering recent events or the names of familiar people or things. They may no longer be able to solve simple math problems or balance a checkbook. People with mild AD also slowly lose the ability to plan and organize. For example, they may have trouble making a grocery list and finding items in the store.
  • Moderate Alzheimer's disease. This is the middle stage of AD. Memory loss and confusion become more obvious. People have more trouble organizing, planning and following instructions. They may need help getting dressed and may start having problems with incontinence. This means they can't control their bladder and/or bowels. People with moderate-stage AD may have trouble recognizing family members and friends. They may not know where they are or what day or year it is. They also may lack judgment and begin to wander, so people with moderate AD should not be left alone. They may become restless and begin repeating movements late in the day. Also, they may have trouble sleeping. Personality changes can become more serious. People with moderate AD may make threats, accuse others of stealing, curse, kick, hit, bite, scream or grab things.
  • Severe Alzheimer's disease (also called late-stage). This is the last stage of Alzheimer's and ends in the death of the person. In this stage, people often need help with all their daily needs. They may not be able to walk or sit up without help. They may not be able to talk and often cannot recognize family members. They may have trouble swallowing and refuse to eat.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.