How is Alzheimer's disease diagnosed?
A definite diagnosis of Alzheimer's disease (AD) is made by autopsy. Pathologists are trained to find certain abnormal structures in the patient's brain that are characteristic of AD. In life, the key is diagnosing dementia and explaining the cause of this diagnosis.
Dementia describes a syndrome of at least 6 months of declines in two or more domains of cognition that interfere with usual and every day activities such as managing money, using transportation, doing household chores and shopping. Dementia is caused by many different kinds of conditions and diseases, such as lead poisoning, HIV infection and neurodegenerative diseases. Among persons over 65, the most common cause of dementia is the neurodegenerative disease called Alzheimer's disease.
There are several tools used to diagnose AD:
- A complete medical history includes information about the person's general health, past medical problems, and any difficulties the person has carrying out daily activities, such as handling finances, driving, shopping, taking care of a household.
- Medical tests, such as tests of blood, urine, or spinal fluid, help find other possible diseases causing the symptoms.
- Cognitive tests- Each patient undergoing an evaluation receives a brief paper and pencil test of their memory, language function and problem solving skills. The test usually takes one hour and is administered by a psychometrician. The test is helpful in detecting and quantifying problems and in monitoring changes over time.
- A CT or MRI of the brain help to look at brain size and structure to assess whether other diseases, e.g., stroke, hemorrhage, etc might be present and contributing to brain dysfunction.
Why is early diagnosis important?
An early, accurate diagnosis of AD is important to ascertain whether there is a potential underlying medical condition or medication that is causing or contributing to the symptoms. It helps patients and their families plan for the future. Persons in the mild stage of the disease are often able to make decisions as well as they did before the diagnosis. But by the moderate stages of the disease, decision making abilities decline markedly. Early diagnosis also offers the best chance to treat the symptoms of the disease.
More information on how AD is diagnosed
The following publications provide detailed information on diagnostic procedures, including examples of a cognitive function assessment and a diagnostic case study.
Jason Karlawish, MD and Christopher Clark, MD discuss the current and potential new diagnostic procedures. This article was published in the March 2003 issue of the Annals of Internal Medicine (138: 400-410).
Jason Karlawish, MD and Christopher Clark, MD present a case study of an elderly patient with mild memory problems, and provide a detailed description of the diagnostic evaluation. This article was published in the March 2003 issue of the Annals of Internal Medicine (138:411:419) .