Johns Hopkins Medicine

Alzheimer's Disease Research Center

Information for Parents and Caregivers

What is Alzheimer's Disease?

the diseaseAlzheimer's disease is a disorder occurring primarily in late life in which the patient's memory, thinking and behavior are impaired because specific brain cells degenerate. With the passage of time, Alzheimer's disease gets steadily worse. At the present time, there is no cure. The Alzheimer's disease Association estimates that 4 million Americans have Alzheimer's disease and 100,000 die of the disease each year.

Many individuals show early symptoms of the disease when they are in their 60s or early 70s. Some people fear that occasional forgetfulness, like misplacing keys or not remembering a name, is a sign of Alzheimer's disease. However, this kind of ordinary memory loss does not mean that a person has Alzheimer's disease.

Initially, memory impairments in Alzheimer's disease are mild but eventually they begin to impact on the life of affected individuals, diminishing their ability to work or function normally. They forget easily and often repeat the same questions even after hearing the answer. They lose objects, or forget where they are, how they got there and how to get home. They begin having trouble with language, judgment, problem solving and calculating numbers. Their mood may change suddenly, swinging from calm to rage and back again within minutes, without apparent reason. Dealing with these individuals may be very difficult for family members or caregivers.

These changes occur slowly and may at first be mistaken for simple forgetfulness. However, in Alzheimer's disease, patients grow progressively worse. Medications can only improve some of the symptoms.

What are the risk factors for developing Alzheimer's disease?

Age is the prime risk factor. Older individuals are the most likely to develop Alzheimer's disease. About 7% of all people over 65 and perhaps 35-40% of persons over 80 develop Alzheimer's disease.

In rare cases, people younger than 60 develop the disease. This occurs particularly in individuals who have a family tendency for the disorder. There are at least 3 genes which, when mutated, cause Alzheimer's disease:

  • APP gene (chromosome 21)
  • Presenilin 1 gene (chromosome 14)
  • Presenilin 2 gene (chromosome 19)

One other gene is a risk factor; the ApoE4 gene. This gene does not cause the disease, but the presence of copies of certain forms of its gene products predisposes the elderly to Alzheimer's disease.

These genetic factors interact in complex ways, which are best studied in animal model systems.

How is Alzheimer's disease diagnosed?

Alzheimer's disease is just one of a variety of forms of dementia, the term used to describe a decline in mental ability. Doctors rule out other causes of dementia, particularly those that are treatable. These other diseases can often mimic Alzheimer's disease. Clinical history, neuropsychological testing, laboratory studies and imaging technologies are used to enhance the diagnosis, but unfortunately, other than by examining brain tissue, there is no way to test for Alzheimer's disease in living persons. With time, particularly following several examinations, the diagnosis of Alzheimer's disease becomes more certain.

To diagnose Alzheimer's disease, physicians:

  • Review the patients' medical history;
  • Perform physical, neurological and psychiatric evaluations;
  • Perform neuropsychological testing;
  • Order laboratory exams.

Sometimes computerized tomography (CT), magnetic resonance imaging (MRI) or positron emission tomography (PET) are performed on the patient to rule out other, treatable conditions. In specialty centers like the Johns Hopkins Alzheimer's Disease Research Center, this combination of approaches is about 90% accurate in confirming Alzheimer's disease. However, absolute proof for a diagnosis can only be confirmed by examining the brain tissue (in a biopsy during life or a brain autopsy after death).

How is Alzheimer's disease treated?

There are five medications approved by the FDA for symptomatic treatment of Alzheimer's disease. These medications (listed below) improve cognition somewhat but do not change the rate of decline of the disease. The major goal of Alzheimer's disease research is to find improved treatments for patients.

DRUG ACTIVITY PROPOSED MECHANISM OF ACTION
Cognex Acetylcholinesterase Inhibitor Increased levels of Acetylcholine
Aricept Acetylcholinesterase Inhibitor Increased levels of Acetylcholine
Exelon Acetylcholinesterase Inhibitor> Increased levels of Acetylcholine
Reminyl Acetylcholinesterase Inhibitor Increased levels of Acetylcholine
Memantine NMDA Receptor Antagonist Reduced levels of N-methyl-D-aspartate (NMDA)

Patients with Alzheimer's disease are also given medications to reduce behavioral problems, when they occur. These problems include: depression, agitation, sleep disorders, hallucinations and delusions.

For more information on caring for Alzheimer's patients, read: The 36-Hour Day

36-Hour DayA Family Guide to Caring for Persons with Alzheimer disease, Related Dementing Illnesses, and Memory Loss in Later Life. Co-authored by Peter Rabins, MD, MPH, the co-director of the Geriatric Psychiatry Program at Johns Hopkins