Diagnosis

The diagnosis of Alzheimer's disease is made based on the symptoms and signs of the disease, the results of diagnostic or other tests, and information from family or friends. In order to make a diagnosis of Alzheimer's disease, the criteria for dementia must be met.

That means that the symptoms must have developed slowly and gradually, and the symptoms cannot be attributed to another disease. In order to rule out other diseases, the demented person should have a brain scan during the early stages.

The diagnosis can be divided into three degrees of certainty:

• Possible Alzheimer's disease. This is the lowest degree of certainty in the diagnosis. In this instance, the symptoms and the course indicate that in all likelihood, it is Alzheimer's disease. There may be specific, atypical symptoms or changes in a brain scan that are not normally observed in Alzheimer's disease.
• Probable Alzheimer's disease. This is the highest degree of certainty that is attainable for the diagnosis being correct without taking a tissue sample from the brain. In this instance, the symptoms, course and examinations all indicate that it is Alzheimer's disease.
• Definite Alzheimer's disease. It is only possible to be completely certain it is Alzheimer's disease if a tissue sample from the brain shows characteristic Alzheimer’s changes. The final and 100% certain diagnosis therefore normally cannot be made until an autopsy after the person has died.