Causes and Diagnoses

Causes and Diagnoses of Alzheimer's Disease

Who Gets Alzheimer’s disease?
The two main categories of Alzheimer's disease (AD) are familial and sporadic. Familial Alzheimer's disease refers to a genetic form of the disease that is transmitted from one generation to the next. Only 5 percent of all cases of Alzheimer's disease have been associated with a genetic component. These individuals come from families in which as many as half of the members develop Alzheimer's disease. Fortunately, this form of the disorder is rare.  The remaining 95 percent of Alzheimer's disease cases are sporadic, or randomly occurring in the population.

A variety of "risk factors" have been identified in individuals diagnosed with AD.  In fact, it is quite common to pick up a newspaper or to turn on the TV and hear about the newest "risk factor" that has been identified. While some of these factors may turn out to be useful, it is important to remember that much of the research that has been done in this area is retrospective research. This means that the research is conducted by comparing a group of patients diagnosed with AD with a group of healthy age-matched adults. These types of analyses provide information about the number of individuals diagnosed with AD who have a certain characteristic compared with the healthy individuals. While these results are useful in directing future research studies, they do not provide information about cause and effect. What is needed is a prospective study in which large numbers of individuals are followed from an early age to the age at which AD develops.

Making a Diagnosis
The absolute diagnosis of Alzheimer's disease can only be made at autopsy. However, physicians at specialized centers can diagnose Alzheimer's disease with 90 percent certainty based on clinical information. To make the diagnosis the following may need to be conducted:
  1. A medical history and neurological exam
  2. Neuropsychological testing
  3. Neuropsychological testing involves a careful analysis of a person's memory, problem solving, language, attention, and visuospatial ability.
  4. Basic blood tests
  5. Blood tests may be used to help exclude other causes of memory difficulties. For example, a person with a thyroid disorder or a vitamin deficiency may have problems with his or her memory.
  6. Brain scans
  7. A brain scan such as an MRI or a CT scan may need to be done in certain patients to detect brain tumors or strokes. These disorders may cause memory problems.