dementia

American  

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

noun

• dementias
  plural

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

Derived Forms

• demential
  adjective

Inflected Forms

Nouns

• dementias
  plural

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

See Examples For:

dementia dementias

Issues such as having a parent or sibling with dementia, as well as traumatic brain injury, increase your overall dementia risk, however.

From MarketWatch ● Aug. 17, 2026

The tissue had been removed during tumor surgery from people with dementia as well as non-dementia patients.

From Science Daily ● Aug. 17, 2026

The group says pioneering treatments and tests "unimaginable just a decade ago" are now within reach, saying those living with dementia should be supported to take part in the research.

From BBC ● Aug. 17, 2026

Lifestyle factors — such as diet, sleep, regular exercise, managing blood pressure and blood sugar, avoiding tobacco and alcohol — can reduce the risk of dementia by up to 45%, Tan said.

From MarketWatch ● Aug. 17, 2026

I drove down to speak with his doctor, who told me that Walter had advancing dementia, likely trauma-induced, and that he would need constant care.

From "Just Mercy" by Bryan Stevenson

While most Americans believe lifestyle behaviors are very important for brain health, fewer than half strongly link these behaviors with reducing the risk of Alzheimer’s or other dementias, the group said.

From MarketWatch ● Jul. 15, 2026

Meinor loved her job in public health, and had been developing a program for Alzheimer’s and related dementias.

From The Wall Street Journal ● Apr. 25, 2026

In Alzheimer's and other dementias, this damage may occur in blood vessels and brain tissue.

From Science Daily ● Apr. 22, 2026

Researchers at the University of Bath, in collaboration with the Universities of Oxford and Bristol, have developed a molecule that prevents the clumping and build-up of a protein linked to Parkinson's disease and related dementias.

From Science Daily ● Oct. 8, 2025

In benign stupor purely mental stimuli may change the whole clinical picture abruptly and with this produce a change in the intellectual functioning such as we never see in organic dementias or clouded states.

From Benign Stupors A Study of a New Manic-Depressive Reaction Type by John T. (John Thompson) MacCurdy

Related Words

• brain damage
• mental disorder