Alzheimers Home > Causes of Dementia

There are many potential dementia causes. The most common cause is Alzheimer's disease, which is responsible for more than half of all dementia cases. Other common causes of the condition include a brain tumor, brain cancer, hypothyroidism, and vitamin B12 deficiency. Some of the less-common causes include Huntington's disease, Creutzfeldt-Jakob disease, and neurosyphilis.

What Are the Causes of Dementia?

Dementia is a descriptive term for a collection of symptoms (such as personality changes, memory problems, and behavioral problems) that can be caused by a number of conditions that affect the brain.
All forms of dementia result from the death of nerve cells or the loss of communication among such cells. The human brain is complex and intricate -- many factors can interfere with its functioning. Although dementia research scientists have uncovered many of these factors, they do not yet have a complete understanding of how dementias develop.
There are many potential causes of dementia. About 10 percent of these are treatable conditions, meaning that the progression of dementia can be reversed or at least stopped with early dementia treatment. For the rest, there are no known treatment options available that can stop the progression of dementia symptoms.
Although Alzheimer's disease and certain other conditions are technically causes of dementia, they are also often referred to as types of dementia. Likewise, terms such as "vascular dementia" are often used to describe causes as well as types of dementia.

Specific Dementia Causes

The most common cause of dementia is Alzheimer's disease. Over 50 percent of people diagnosed with dementia have Alzheimer's disease. Other common causes include:
Other dementia causes that are not as common include:
  • Huntington's disease.
  • Infection, including a syphilis infection of the brain (known medically as neurosyphilis).
  • Chronic subdural hematoma.
  • Lewy body dementia.
  • Frontotemporal dementia.
  • Pick's disease.
  • Parkinson's disease.
  • HIV.
  • CADASIL, which stands for cerebral autosomal dominant arteriopathy with subcortical infarct and leukoencephalopathy. CADASIL is a rare hereditary condition.
  • Creutzfeldt-Jakob disease.
There are also a number of conditions that can cause dementia in children.
(Click Childhood Dementia to learn about these dementia causes in children.)
Written by/reviewed by:
Last reviewed by: Arthur Schoenstadt, MD
Last updated/reviewed:
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