Medical Encyclopaedia › Dementia (short definition)
In brief: Dementia is an umbrella term for diseases in which memory, thinking, orientation and everyday skills decline permanently and progressively. An estimated 1.8 million people live with dementia in Germany; the risk rises sharply with age.
Types
The most common form is Alzheimer’s disease, in which protein deposits (amyloid plaques and tau fibrils) form in the brain and nerve cells die. The second most common cause is vascular dementia due to circulatory disorders and small strokes; mixed forms are common. Other forms are dementia with Lewy bodies, frontotemporal dementia and dementia in Parkinson’s disease.
Signs
Early indications are increasing forgetfulness for new information, word-finding difficulties, problems with planning, money or appointments, disorientation in unfamiliar places, and changes in mood and behaviour. Occasional forgetfulness, by contrast, is normal in old age. Depression, thyroid disorders, vitamin B12 deficiency or side effects of medicines can also cause dementia-like symptoms and are treatable.
Diagnosis
The assessment includes a detailed conversation, also with relatives, cognitive tests, a physical and neurological examination, blood tests and brain imaging. In certain cases, biomarkers in the cerebrospinal fluid or special nuclear medicine procedures are used; blood tests for Alzheimer’s biomarkers are currently being introduced into routine care.
Treatment
Most forms of dementia cannot yet be cured. In mild to moderate Alzheimer’s dementia, acetylcholinesterase inhibitors (donepezil, galantamine, rivastigmine) and, in moderate to severe forms, memantine can stabilise the symptoms for a time. For early stages of Alzheimer’s disease, antibodies against amyloid have been approved in the EU for the first time; they can moderately slow progression, are only suitable for selected patients and require regular MRI monitoring because of possible brain swelling and bleeding. Equally important are non-drug approaches such as cognitive stimulation, exercise, occupational therapy, music and reminiscence work, and support and training for relatives.
Risk factors and prevention
Some dementias are linked to modifiable factors, including high blood pressure, diabetes, overweight, smoking, lack of exercise, high alcohol consumption, untreated hearing loss, social isolation and depression. A heart-healthy lifestyle, mental and social activity and treatment of hearing loss can reduce the risk, but cannot reliably prevent dementia.
Related terms in the encyclopaedia
Alzheimer’s disease, Vascular dementia, Dementia with Lewy bodies, Frontotemporal dementia, Mild cognitive impairment, Acetylcholinesterase inhibitors, Memantine, Lecanemab, Care level (Pflegegrad), Long-term care insurance
Sources
- DGPPN und DGN: S3-Leitlinie „Demenzen“, AWMF-Register 038-013
- Deutsche Alzheimer Gesellschaft: Informationsblätter zur Häufigkeit und Versorgung von Demenzerkrankungen
- Livingston G. et al.: Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission, The Lancet 2024
Note: This article is for general information and does not replace advice, diagnosis or treatment from a doctor or pharmacist. Last updated: October 2026.