dementia

American  

[dih-men-shuh, -shee-uh] / dɪˈmɛn ʃə, -ʃi ə /

noun

1. a condition characterized by progressive, persistent, severe impairment of intellectual capacity, including memory loss, confusion, and emotional instability, resulting from the loss of or damage to neurons in the brain.

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dementia British  

/ -ʃɪə, dɪˈmɛnʃə /

noun

1. a state of serious emotional and mental deterioration, of organic or functional origin

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dementia Scientific  

/ dĭ-mĕn′shə /

1. Deterioration of intellectual faculties, such as memory, concentration, and judgment, sometimes accompanied by emotional disturbance and personality changes. Dementia is caused by organic damage to the brain (as in Alzheimer's disease), head trauma, metabolic disorders, or the presence of a tumor.

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Other Word Forms

• demential
  adjective

Etymology

Origin of dementia

First recorded in 1800–10; from Latin dēmentia “madness,” equivalent to dēment- “out of one's mind” ( see dement) + -ia noun suffix

Compare meaning

How does dementia compare to similar and commonly confused words? Explore the most common comparisons:

• dementia vs. senility

Explanation

If your grandfather suffers from dementia, he has a brain disorder that's causing him to gradually lose his memory and become disoriented and confused. Although dementia is most common in elderly people, it's not a normal part of growing older but a syndrome caused by brain disease or injury. Dementia gets its name from the Latin words de, or "without," and mens, or "mind," which join together to mean "madness," although in English, dementia is not the same thing as madness. One example of an illness that causes dementia is Alzheimer's disease.

Example Sentences

The findings suggest the same dementia risk factor may not affect everyone equally.

From Science Daily • May 20, 2026

"These differences highlight the importance of considering sex as a key variable in dementia research," said Pa. "Sex differences are profoundly overlooked among many leading causes of death like Alzheimer's, heart disease and cancer."

From Science Daily • May 20, 2026

The lifetime risk of dementia after age 55 is about 42%, according to a 2025 study published in the journal Nature Medicine.

From MarketWatch • May 19, 2026

The group was founded a decade ago by Stewart’s father Sir Jackie Stewart, a three-time F1 champion and one of the most successful drivers in racing history, after his wife Helen was diagnosed with dementia.

From Los Angeles Times • May 18, 2026

The doctor also said the dementia would progress and that Walter would likely become incapacitated.

From "Just Mercy" by Bryan Stevenson

Related Words

• brain damage
• mental disorder