What is Alzheimer’s disease?
Alzheimer’s disease—a progressive, degenerative brain disorder—is one of the most common causes of the loss of mental function known as dementia. Alzheimer’s disease proceeds in stages, gradually destroying memory, reason, judgment, language, and — eventually — the ability to carry out even the simplest tasks.
How common is Alzheimer’s disease?
It is estimated that today one in 10 people over the age of 65 and nearly half of people over 85 have Alzheimer’s disease. Patients with Alzheimer’s disease often live for years, dying eventually from other health problems. The duration of Alzheimer’s disease, from time of diagnosis to death, can be 20 years or more. However, the average duration of the disease is thought to be about four to eight years. As the Baby Boomer generation continues to age, the number of individuals with Alzheimer’s disease will increase dramatically.
What are the symptoms of Alzheimer’s disease?
The symptoms of Alzheimer’s disease can range from mild to severe and can include:
- Confusion and memory loss
- Disorientation; getting lost in familiar surroundings
- Problems with routine tasks, such as eating, dressing, and using the toilet
- Difficulty remembering words and/or their meanings; communication problems
- Anxiety, suspiciousness, and agitation
- Sleep disturbances
- Wandering/pacing
- Difficulty recognizing friends and family
- Loss of speech
- Loss of appetite; weight loss
- Loss of bladder and bowel control
- Total dependence on caregivers
How is Alzheimer’s disease diagnosed?
Despite its prevalence, Alzheimer’s disease often goes unrecognized or is misdiagnosed in its early stages. Many health professionals, patients, and family members mistakenly view the early symptoms of Alzheimer’s disease as the inevitable consequences of aging.
Some disorders that can result in dementia—such as depression, poor nutrition, and drug interactions—are reversible, but Alzheimer’s disease is irreversible. Therefore, it is very important to diagnose the cause of the dementia early and correctly. In addition, some Alzheimer’s disease symptoms—such as incontinence and depression—can be effectively treated.
Alzheimer’s disease cannot be positively diagnosed until after death, when the brain can be closely examined for certain microscopic changes caused by the disease. However, through thorough testing and a "process of elimination," doctors today can diagnose probable Alzheimer’s with almost 90 percent accuracy.
An early and accurate diagnosis of the cause of dementia is important for the following reasons:
- To rule out Alzheimer’s disease, and ease the patient’s and family’s concern
- To identify any treatable condition and initiate treatment as appropriate
- To identify Alzheimer’s disease at the earliest stage possible, which gives the patient and family time to plan for the future needs and care of the patient
The following diagnostic tools are used to help make a diagnosis of Alzheimer’s disease:
- Patient history – This includes a thorough review of the patient’s family history, as well as an evaluation of when and how the patient’s symptoms developed.
- Physical exam – This includes a complete physical examination, chest X-ray and laboratory tests (blood work, urinalysis) to help identify or rule out other possible causes of dementia.
- Brain scans – These tests, usually a CT and/or an MRI scan, are done to identify or rule out strokes, tumors, or other problems that can result in similar symptoms.
- Electroencephalogram (EEG) – This is a diagnostic test that records the brain’s electrical activity by means of electrodes applied to the scalp.
- Electrocardiogram (ECG or EKG) – This is a test that records the electrical activity of the heart and shows any abnormalities in heart rhythm.
- Neuropsychological testing – This includes a series of specialized tests that measure memory, language skills, ability to do arithmetic, and other abilities related to brain function.
In addition, the following tests also might be done to help diagnose and monitor the progression of Alzheimer’s disease:
- Positron emission tomography (PET) scan — This is an imaging scan that measures the level of functional activity of the brain by measuring its use of glucose.
- Single photon emission computed tomography (SPECT) scan — This is a procedure that measures blood flow in different areas of the brain.
- Magnetic resonance spectroscopy imaging (MRSI) — This test allows the doctor to observe certain substances throughout the brain without the use of radioactive materials.
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 11/8/2008...#9177.
