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.

---

dementia British  

/ -ʃɪə, dɪˈmɛnʃə /

noun

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

---

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.

---

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

I recently wrote about the elaborate ruse one daughter created to get her parents, who showed signs of dementia and self-neglect, out of their home.

From The Wall Street Journal ● Jul. 25, 2026

APOE2, by contrast, has repeatedly been linked in population studies to longer life and a reduced risk of dementia.

From Science Daily ● Jul. 24, 2026

Read: Most Americans don’t know how to prevent dementia.

From MarketWatch ● Jul. 21, 2026

Soon after his dementia diagnosis in 2019, Bloom’s 66-year-old husband, Brian Ameche, expressed his wishes clearly.

From MarketWatch ● Jul. 20, 2026

During that initial interview, the farmer had seemed to be suffering from dementia: he had stared at the agent blankly.

From "Killers of the Flower Moon" by David Grann

Medicare and Medicaid are expected to cover $263 billion, or 64%, of the total healthcare and long-term-care payments for people living with Alzheimer’s or other dementias.

From MarketWatch ● May 19, 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

It could also help identify people at higher risk of developing Alzheimer's disease and related dementias, even before any symptoms appear.

From Science Daily ● Apr. 22, 2026

Despite APOE's strong influence, it is not the sole cause of Alzheimer's or other dementias.

From Science Daily ● Jan. 23, 2026

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 MacCurdy, John T. (John Thompson)

Related Words

• brain damage
• mental disorder