In plain words
Dementia affects memory, thinking and the ability to do daily activities. It is caused by diseases that damage the brain and gets worse over time. It is more common after 65 but is not an inevitable part of ageing.
Key facts
- In 2021 about 57 million people lived with dementia worldwide, over 60% in low- and middle-income countries, with nearly 10 million new cases a year.
- Alzheimer disease is the most common form and may account for 60 to 70% of cases.
- Dementia is the seventh leading cause of death (WHO).
- In 2019 it cost economies US$1.3 trillion, about half from care by informal carers, who give on average 5 hours of care and supervision a day. Women provide 70% of care hours.
Early signs
Forgetting recent events, misplacing things, getting lost, confusion in familiar places, losing track of time, trouble solving problems or deciding, difficulty following conversations or finding words, trouble with familiar tasks, misjudging distances.
Risk factors
Health conditions: high blood pressure, high blood sugar, overweight or obesity, depression, vision and hearing loss, poor sleep, traumatic brain injury and stroke. Lifestyle: tobacco, harmful alcohol use, inactivity, social isolation, low education. Environment: air pollution.
Impact
Physical, psychological, social and economic effects on the person, carers, families and society. Low awareness leads to stigma and barriers to diagnosis and care.
Sources
- WHO fact sheet, Dementia, published 3 July 2026, read 9 October 2026.
Last reviewed: 9 October 2026. Reviewer: none yet. This page is general education and is not medical advice. Figures are WHO's and may have been updated since.