Dementia: An Overview

Types of Dementia

What are the Different Types of Dementia?

Dementias can be grouped in different ways.^[3] Here's one of the more common ways to group dementias:

• Cortical dementia - brain damage that affects the cortex of the brain or the outer layer. This type of dementia tends to cause problems with memory, language, thinking and social behavior.
• Subcortical dementia - affects the area below the cortex. This type of dementia tends to cause changes in emotions and movement in addition to memory problems.

Another common way to group dementias:

• Primary dementia - the main problems are from dementia and not some other disease. Alzheimer's disease is a primary dementia.
• Secondary dementia - dementia is the result of disease or injury. Multi-infarct dementia is an example of this type of dementia.
• Progressive dementia - dementia gets worse over time and gradually increases the number of problems with thinking.

Examples of Cortical Dementia

Alzheimer's disease is a cortical dementia. It is the most common dementia among people age 65 and older. Experts believe that as many as 4 million people in the United States have Alzheimer's disease and that 50,000 die from it each year. In the early stages, people have memory problems, poor judgment and mild changes in personality. Over time, memory gets worse and thinking is impaired. People with Alzheimer's disease may also have problems with vision and spatial orientation. They may get lost and may not remember what day it is. They may also have delusions (believing things that aren't true) and become short-tempered. During the final stages of the disease, people lose control over essential functions such as swallowing and bowel and bladder control. They lose the ability to recognize family members and to speak. They become aggressive, agitated, depressed, and unable to sleep. Typically, people with Alzheimer's disease live from 8 to 10 years after diagnosis.

Creutzfeldt-Jakob disease is an example of a cortical dementia. This is a rare disease that affects one out of million people. Typically, symptoms begin after age 60 and people die within one year of the first symptoms appearing. Researchers believe the disease is caused by a prion, which is a protein. The protein is formed incorrectly and forms clumps in the brain causing death of brain cells. About 5% of cases are due to a genetic mutation. The cause of most of the rest of the cases is unknown. A very small number are caused by eating beef from cows with mad cow disease. This form is considered a variant of Creutzfeldt-Jakob disease and is abbreviated vCJD. The first symptoms of the disease involve problems with muscle coordination, personality changes including poor memory, judgment and thinking. They also have impaired vision. With time, mental impairment worsens. Eventually people lose the ability to move and speak. The disease is always fatal.

Examples of Subcortical Dementia

Parkinson's disease is an example of a subcortical dementia.^[6][7] Parkinson's impairs muscle function and causes trembling of hands, arms and face as well as stiffness of the limbs. It also causes slow movement and impaired balance. Parkinson's disease affects about one million people in the United States.^[8] The disease usually affects people over age 50 and affects men more than women.

Huntington's disease is an inherited, subcortical dementia.^[9] The disease causes problems with movement, loss of higher brain function and emotions. If a parent has Huntington's disease, each child has a 50% chance of inheriting it. Only one copy of the gene for Huntington's disease is required for it to develop. Symptoms usually appear between the ages of 30 and 50.^[10] More than 15,000 Americans have Huntington's disease.

This Elder Health Guide was published on October 13, 2009 and was updated on November 2, 2009.