What Is Dementia?

What Is Dementia?

Dementia causes problems with thinking, memory, and reasoning. It happens when the parts of the brain used for learning, memory, decision making, and language are damaged or diseased.

Also called major neurocognitive disorder, it's not a disease itself. Instead, it's a group of symptoms caused by other conditions.

Alzheimer's disease is the most common cause of dementia. Between 60% to 80% of people with dementia have Alzheimer's. But there are as many as 50 other causes of dementia.

The symptoms of dementia may improve with treatment. But many of the diseases that cause dementia aren't curable.

What Causes Dementia?

The most common causes of dementia include:

Types of Dementia

Dementia can be split into two groups based on which part of the brain is affected.

  • Cortical dementias happen because of problems in the cerebral cortex, the outer layer of the brain. They play a critical role in memory and language. People with these types of dementia usually have severe memory loss and can't remember words or understand language. Alzheimer's and Creutzfeldt-Jakob disease are two forms of cortical dementia.
  • Subcortical dementias happen because of problems in the parts of the brain beneath the cortex. People with subcortical dementias tend to show changes in their speed of thinking and ability to start activities. Usually, people with subcortical dementia don't have forgetfulness and language problems. Parkinson's disease, Huntington's disease, and HIV can cause these types of dementia.

Some types of dementia affect both parts of the brain.

Are There Treatments for Dementia?

To treat dementia, doctors will treat whatever is causing it. About 20% of the causes of dementia are reversible.

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Causes of dementia that may be reversible include:

These forms of dementia are partially manageable, but they aren't reversible and get worse over time:

What Are the Stages of Dementia?

Usually, dementia goes through these stages. But it may vary depending on the area of the brain that is affected.

1) No impairment: Someone at this stage will show no symptoms, but tests may reveal a problem.

2) Very mild decline: You may notice slight changes in behavior, but your loved one will still be independent.

3) Mild decline: You'll notice more changes in his thinking and reasoning. He may have trouble making plans, and he may repeat himself a lot. He may also have a hard time remembering recent events.

4) Moderate decline: He'll have more problems with making plans and remembering recent events. He may have a hard time with traveling and handling money.

5) Moderately severe decline: He may not remember his phone number or his grandchildren's names.He may be confused about the time of day or day of the week. At this point, he will need assistance with some basic day-to-day functions, such as picking out clothes to wear.

6) Severe decline: He'll begin to forget the name of his spouse. He'll need help going to the restroom and eating. You may also see changes in his personality and emotions.

7) Very severe decline: He can no longer speak this thoughts. He can't walk and will spend most of his time in bed.

How Common Is Dementia?

About 5% to 8% of adults over age 65 have some form of dementia. This percentage doubles every 5 years after 65. As many as half of people in their 80s have some dementia.

WebMD Medical Reference Reviewed by Neil Lava, MD on December 22, 2015

Sources

SOURCES: 

National Institute of Neurological Disorders and Stroke: "Dementia: Hope Through Research."

American Psychiatric Association: "Seniors."

National Institute of Neurological Disorders and Stroke: "NINDS Dementia Information Page."

UpToDate: "Patient information: Dementia (including Alzheimer disease) (Beyond the Basics)."

National Institutes of Health: "HIV Associated Neurocognitive Disorders."

Alzheimers.net: "What are the 7 Stages of Alzheimer's Disease?"

Fisher Center for Alzheimer's Research Foundation: "Clinical Stages of Alzheimer's."

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