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Brain & Nervous System Health Center

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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.

Recommended Related to Brain & Nervous System

Ménière's Disease

Important It is possible that the main title of the report Ménière's Disease is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.

Read the Ménière's Disease article > >

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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