What is Alzheimer's Disease?
Alzheimer's disease (AD), the most common cause of dementia, is a progressive brain disorder. Learn about the causes, signs and research being ...

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The most common cause of dementia is Alzheimer’s disease (AD). AD is a progressive and irreversible brain disorder. The actual cause of AD is unknown. AD slowly damages, and then destroys, a person’s memory, judgment, reasoning skills, personality, autonomy, and bodily functions. 

The disease specifically affects several components of the brain. These include:

  • a gradual loss of brain cells, called neurons
  • damage to neurons so they no longer function properly
  • the loss of neural connections—called synapses— where messages are passed from neuron to neuron

Forgetfulness: A Normal Part of Aging?

It’s normal to sometimes forget things, but as we age, it often takes longer to learn new skills or remember words, names, or where we left our glasses. Of course, this does not mean an individual has dementia. In fact, scientists have found that healthy older adults perform just as well as their young counterparts on complex and learning tests—if given extra time to complete.  

However, there’s a difference between occasional forgetfulness and behavior that may be cause for concern. Not recognizing a familiar face, trouble performing common tasks (such as using the telephone or driving home); or being unable to comprehend or recall recent information are all red flags that need to be checked by a medical professional.

Who Gets AD?

Also known as late-onset Alzheimer’s disease, AD is primarily a disease of the elderly. The first noticeable symptoms can occur as early as age 60.

When AD runs in families, it’s called familial Alzheimer’s disease (FAD). 

AD sometimes can affect people as young as 30. This type of AD is called early-onset AD. It is rare and affects less than one out of every 1,000 people with AD.

The underlying cause or causes of AD, and specific risk factors, remain unclear. Yet experts believe AD is likely due to a combination of environmental and genetic factors. Lifestyle choices, such as diet, exercise, and staying mentally active like learning new skills, also are factors. 

About 5.3 million Americans have AD, according to the National Institutes of Health (NIH). That number will only climb as the elderly population rises.

AD is the sixth leading cause of death in the U.S. and the fifth leading in Americans age 65 and older. Worldwide, approximately 24 million people have AD.

What’s Being Done?

Scientists are working to better understand AD in order to create more effective early diagnostic tools, improve treatments, and perhaps even discover a cure. 

In terms of what’s immediately available, there are numerous reputable resources and services for people who suffer with AD and their loved ones and caregivers. Some current treatment options even may slow the progression of AD, however, their effectiveness varies and diminishes over time.

Written by: Wendy Leonard, MPH
Edited by:
Medically Reviewed by: Jennifer Monti, MPH, MD
Published: May 11, 2011
Published By: Healthline Networks, Inc.
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