Alzheimer’s Disease


What Is It?

Alzheimer’s disease impairs the brain’s intellectual functions (memory, orientation, calculation), but at first, largely spares those parts of the brain that control sensation and movement. The memory often is affected early, and gradually deteriorates, causing impaired judgment and other problems that may affect a person’s ability to perform normal daily activities. Although Alzheimer’s usually begins later in life, generally after age 60, it rarely may affect people as young as age 30.

In Alzheimer’s disease, deposits of proteins called amyloid and TAU distort communication between brain cells. Also levels of a chemical called acetylcholine that helps transmit messages between brain cells begin to drop, causing more communication problems. Eventually, brain cells themselves are affected. They begin to shrivel and die, causing certain areas of the brain to shrink.

Alzheimer’s disease is the most common cause of dementia, accounting for 50 percent to 67 percent of all cases in people age 65 and older. Approximately 4 million people in the United States currently have the disease.

Everyone is born with the potential to develop Alzheimer’s disease. Your lifetime risk of developing the disease is about 10 percent to 15 percent. However, several factors may increase your risk:

  • Age — The older you get, the greater your chance of developing Alzheimer’s disease.

  • Family history — If members of your family, especially parents or siblings, have Alzheimer’s or have died from it, your risk of developing the disease increases to 23 percent to 48 percent. Your personal risk depends on a range of factors, including how many family members are affected with Alzheimer’s.

  • Genetic factors — Some inherited factors may increase your lifetime risk of getting Alzheimer’s disease.


In the earliest stages of Alzheimer’s disease, new or recent memories are difficult to recall. The person finds it hard to learn and retain new information. Eventually, older or more distant memories are gradually lost. It becomes difficult to remember people and events from childhood, youth or middle age. Next, other symptoms may appear, including difficulty expressing thoughts as spoken words (aphasia), difficulty carrying out simple, directed acts (apraxia) and difficulty interpreting familiar faces or other well-known objects (agnosia).

A person with early Alzheimer’s disease may not be able to plan meals, manage money, remember to keep doors locked or take medicines. The person also may lose his or her sense of direction and get lost while driving or walking, even in a familiar neighborhood.

Despite all these problems, a person with early Alzheimer’s disease usually is able to feed, bathe, dress and groom without help. Psychiatric symptoms (personality changes, irritability, anxiety, depression) occur in up to two-thirds of people early in the illness. These may cause serious problems in relationships with family and friends.

As Alzheimer’s disease progresses to its middle and late stages, there may be delusions (irrational beliefs, especially about being persecuted or having one’s belongings stolen) and hallucinations (seeing, hearing, smelling, tasting or being touched by something that isn’t really there). The patient also may become aggressive or may begin to wander away from home if left alone.


By interviewing both the patient and family members, your doctor will determine whether the patient has any of the following problems: memory lapses; difficulty using language; problems learning and retaining new information; difficulty following directions or handling complex tasks; episodes of poor judgment or unusual or risky behaviors. Next, your doctor will perform a physical exam to rule out other illnesses that can affect the brain, especially disorders of the heart and circulatory system, which can decrease the brain’s blood supply. Your doctor also will perform a neurological examination (to check the brain and nerves), as well as a brief mental state examination, which includes visual, writing and memory testing. Blood tests to check blood chemistry, liver function and levels of thyroid hormone and vitamin B-12 can help rule out chemical or hormonal causes of brain problems. A blood cell count or a blood test for syphilis may be needed to rule out infection.

In some cases, your doctor may order a brain imaging study to look for evidence of structural changes in the brain that usually are seen in Alzheimer’s disease. This study can also rule out other brain illnesses. A brain imaging study may include a Computed tomography (CT) scan, a magnetic resonance imaging (MRI) scan or a positron emission tomography (PET) scan. Sometimes, when a patient’s symptoms are not typical (10 percent to 20 percent of cases) or when the neurological examination shows signs of a sensory or movement problem, your doctor may refer the patient to a specialist, such as a neurologist, geriatrician or a geriatric psychiatrist, to confirm the diagnosis.

Expected Duration

Alzheimer’s disease is irreversible. Once the diagnosis is made, mental function usually declines over a course of three to 20 years (average 10 years) until death.


Currently, there is no way to prevent Alzheimer’s disease. Nonsteroidal anti-inflammatory drugs may offer some protection. This is being studied. Having a high educational level appears to offer some protection.


Four medications, tacrine (Cognex), donepezil (Aricept), rivastigmine tartrate (Exelon) and galantamine (Reminyl), are used to improve intellectual function in some people with mild to moderate Alzheimer’s disease for periods up to 18 months. These drugs (called cholinesterase inhibitors) increase the brain’s levels of acetylcholine, which helps to restore communication between brain cells. Another medication, memantine (Namenda), has been shown to stabilize memory in people with moderate to severe Alzheimer’s disease. It is the first in a new class of medications called NMDA receptor antagonists.

Other strategies used to help patients with Alzheimer’s include psychotherapy techniques (reality orientation and memory retraining) and medications to relieve depression and calm agitated behavior. Vitamin E also may delay the decline in self-care. It is best used in early stages of the illness.

A doctor should check someone with Alzheimer’s disease every three to six months. The doctor should work closely with family members to provide information about community resources, support groups and nursing home placement (when necessary). As much as possible, the patient should follow a regular exercise routine, maintain normal social contacts with family and friends and continue intellectual activities. Safety concerns, especially driving, should be discussed with the doctor.

New medications currently being tested to treat Alzheimer’s disease include nonsteroidal anti-inflammatory agents, vitamin E and the botanical product ginkgo biloba. A vaccine is being studied in mice, but causes severe brain inflammation in early tests in humans.

Although several nonprescription products claim to improve mental function, the scientific evidence to support this claim is weak. Check with your doctor before taking any nonprescription medication, especially if you are taking a prescription medication for heart problems, diabetes, high blood pressure or mental illness, or if you have problems with your heart or liver.

When To Call A Professional

Call your doctor whenever an older family member has any of the following problems: serious lapses in memory or judgment (forgets medication, forgets the stove is on, allows strangers into the home); disorientation (gets lost) while driving or walking, especially in a familiar neighborhood; a substantial change in personality. The affected person often is unaware of these problems and may even deny that they exist.

Call your doctor immediately if an older family member has any sudden change in personality or mental functions. Sudden changes are usually not a sign of Alzheimer’s disease, but they may be seen in patients with a stroke, a blood clot near the brain or another medical illness that requires emergency treatment.


Although no medication is available to cure Alzheimer’s disease, the cholinesterase inhibitors may improve performance of daily activities, relieve behavior problems or possibly delay the need for a nursing home.


Johns Hopkins patient information

Last revised: December 6, 2012
by Simon D. Mitin, M.D.

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