More than 5 million Americans have Alzheimer's disease (AD). For these individuals there is no cure yet—or even a sure-fire means for halting or preventing the disease. The good news, though, is that some therapy can alleviate symptoms.

What is Alzheimer's disease?

The National Institute on Aging (NIA) describes AD as an irreversible, progressive brain disease that slowly destroys memory and thinking skills, eventually even the ability to carry out the simplest tasks. Although the risk of developing AD increases with age, the disease is not a part of normal aging. It is caused by a disease that affects the brain.

The plaque formation associated with AD disrupts the communication, metabolism, and repair of the neurons (nerve cells in the brain). This disruption causes certain neurons in the brain to stop working, lose connections with other neurons, and finally, die. The destruction and death of neurons causes the memory failure, personality changes, problems in carrying out daily activities, and other features of the disease.

The brains of AD patients have an abundance of two abnormal structures, beta amyloid plaques and neurofibrillary tangles, especially in the region of the brain responsible for memory. Many older people develop some plaques and tangles, but the brains of AD patients have them to a much greater extent.

The causes of the AD process is unknown. The NIA says the time from diagnosis to death varies—from as little as three years if the person is older than 80 when diagnosed, to as long as 10 or more years if the person is younger. In most people with AD, symptoms first appear after age 60. Although the course of AD is not the same in every person with the disease, symptoms seem to develop over the same general stages.

What are the symptoms?

The brain changes that lead to AD probably start 10 to 20 years before any visible signs and symptoms appear. The diagnosis of AD is usually made when mild cognitive impairment becomes evident (called mild AD). Memory loss is usually the first sign. As the disease progresses, memory loss continues and changes in other cognitive abilities appear. According to the NIA, signs of mild AD can include:

  • Memory loss

  • Confusion about the location of familiar places (getting lost begins to occur)

  • Taking longer to accomplish normal daily tasks

  • Trouble handling money and paying bills

  • Poor judgment leading to bad decisions

  • Loss of spontaneity and sense of initiative

  • Mood and personality changes, increased anxiety

In moderate AD, the damage has spread to the areas of the brain that control language, reasoning, sensory processing, and conscious thought. The NIA lists these as symptoms of this stage:

  • Increasing memory loss and confusion

  • Shortened attention span

  • Problems recognizing friends and family members

  • Difficulty with language; problems with reading, writing, working with numbers

  • Difficulty organizing thoughts and thinking logically

  • Inability to learn new things or to cope with new or unexpected situations

  • Restlessness, agitation, anxiety, tearfulness, wandering, especially in the late afternoon or at night

  • Repetitive statements or movement, occasional muscle twitches

  • Hallucinations, delusions, suspiciousness or paranoia, irritability

  • Loss of impulse control shown through sloppy table manners, undressing at inappropriate times or places, or vulgar language

  • Perceptual-motor problems such as trouble getting out of a chair or setting the table

In the last stage, people with severe AD cannot recognize family and loved ones or communicate in any way. They may be in bed nearly all the time. Most people with AD die from other illnesses. A frequent cause is aspiration pneumonia, a type of pneumonia that happens when a person is not able to swallow properly and breathes food or liquids into the lungs.

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More than 5.3 million people in the United States are living with Alzheimer's disease, with a new person developing the disease every 70 seconds. Americans ages 65 and older with Alzheimer's and dementia pay three times as much in health care costs.