Alzheimer's Disease Health Center

Alzheimer's Disease and Other Forms of Dementia

Who Gets Dementia?

Dementia is considered a late-life disease because it tends to develop mostly in elderly people. About 5% to 8% of all people over the age of 65 have some form of dementia, and this number doubles every five years above that age. It is estimated that as many as half of people in their 80s suffer from dementia.

Which Dementias Are Treatable?

• Dementia due to long-term substance abuse.
• Tumors that can be removed.
• Subdural hematoma, accumulation of blood beneath the outer covering of the brain as a result of a broken blood vessel, usually caused by head injury.
• Normal-pressure hydrocephalus.
• Metabolic disorders, such as a vitamin B12 deficiency.
• Hypothyroidism, a condition that results from an underactive thyroid.
• Hypoglycemia, a condition that results from low blood sugar.

What Are Some of the Untreatable Causes of Dementia?

• Alzheimer's disease.
• Multi-infarct dementia (Dementia due to multiple small strokes).
• Dementias associated with Parkinson's disease and similar disorders.
• AIDS dementia complex.
• Creutzfeldt-Jakob disease (CJD), a quickly progressing and fatal disease that consists of dementia and muscle twitching and spasm.