Dozens of diseases or conditions can cause dementia. Some of these dementias are reversible; others are irreversible. Alzheimer’s disease is the most common cause of dementia in persons older than 65. It is irreversible and represents about 60 percent of all dementias. After Alzheimer’s disease, vascular dementia and Lewy body dementia are the most common.
Each type of dementia is characterized by different structural changes in the brain, such as an accumulation of abnormal plaques and tangles in individuals with Alzheimer’s disease, and abnormal tau protein in individuals with frontotemporal dementia.
The clinical symptoms and the progression of dementia vary, depending on the type of disease causing it, and the location and number of damaged brain cells. Some types progress slowly over years, while others may result in sudden loss of intellectual function.
These neurodegenerative diseases—diseases that involve the progressive death or dysfunction of brain cells—can cause dementia:
- Alzheimer’s disease
- Vascular dementia
- Lewy body dementia
- Mixed dementia (Alzheimer’s disease and vascular dementia)
- Parkinson’s disease with dementia
- Frontotemporal dementia
- Huntington’s disease
- Creutzfeldt-Jakob disease
- Niemann-Pick’s disease
- Multi-infarct dementia
Other types of dementia are caused by:
- Brain injury/trauma
- Brain inflammation
Some causes of dementia that can be treated or reversed are:
- Vitamin deficiency
- Thyroid problems
- Medication side effects
- Normal-pressure hydrocephalus
- Metabolic disorders (liver, kidneys, pancreas)
- Hormone imbalance
Dementia is more common later in life, but it is not a normal part of aging.