Northwestern University Feinberg School of Medicine

Northwestern University Feinberg School of Medicine

About Dementia

Overview

Download A PDF Summary of Alzheimer's Disease

Alzheimer's disease is a form of brain degeneration in which abnormal particles called neurofibrillary tangles and neuritic plaques form in the brain and destroy healthy neurons (brain cells). These abnormalities tend to settle in brain areas that control the ability to learn a new fact and remember it 30 minutes, or a day later, a skill we refer to as "memory".

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.

What is dementia?

The term "dementia" is used to describe the gradual deterioration of "intellectual" abilities and behavior that eventually interferes with customary daily living activities. "Customary daily living activities" include balancing the checkbook, keeping house, driving the car, involvement in social activities, and working at one's usual occupation. There may also be changes in personality and emotions. Contrary to popular belief, dementia is not a normal outcome of aging, but is caused by diseases that affect the brain. Dementia influences all aspects of mind and behavior, including memory, judgment, language, concentration, visual perception, temperament, and social interactions. Although dementia symptoms are eventually obvious to everyone, in the early stages special evaluations are necessary to demonstrate the abnormalities.

In people over the age of 65, the most common cause of dementia is Alzheimer's disease. Alzheimer's disease is a form of brain degeneration in which abnormal particles called neurofibrillary tangles and neuritic plaques form in the brain and destroy healthy neurons (brain cells). These abnormalities tend to settle in brain areas that control the ability to learn a new fact and remember it 30 minutes, or a day later, a skill we refer to as "memory". Years of studying dementias have shown that Alzheimer's disease is not the only type of brain degeneration. There are other forms of brain degeneration, many of which can affect people in their 50's or even 40's.

This page last updated Jun 8, 2012

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