Dementia is a clinical syndrome (a set of signs and symptoms) resulting from a progressive impairment of higher brain function, that leads to chronic intellectual and cognitive decline as the most prominent and defined feature of the condition.  Many different functions may be affect: language, attention, spatial orientation, perception, judgment, memory, etc.

Diseases that lead to dementia

Many different diseases can lead to dementia. It can be caused by:

  • Infectious diseases (HIV, meningitis)
  • Vascular diseases (multiple strokes)
  • Neurodegenerative diseases (Parkinson’s disease and Alzheimer’s disease)
  • Brain trauma
  • Long-time alcohol (Korsakoff syndrome)
  • Drug abuse and many others diseases.


A diagnosis of dementia is often made following a thorough history and a cognitive function test – special questionnaires applied by physician or other healthy professional. A diagnosis of dementia must include an impairment of at least two of the following domains:

  • Impaired ability to remember new information
  • Impaired reasoning
  • Impaired visuospatial abilities
  • Impaired language function
  • Changes in personality or behaviour.

Dementia is not a disease in itself. Dementia is a word used to describe a group of symptoms that occur when some brain functions stop to work properly.

Diseases that cause dementia:

  • Alzheimer’s disease, with approx. 60% the most frequent cause of all dementias;
  • Vascular dementia, with about 10-15% of all dementias: The main cause of vascular dementia is vascular damage caused by arteriosclerosis. This leads to long-term circulatory disturbances in the brain.
  • Mixed forms of vascular and Alzheimer’s dementia in about 20% of cases.
  • Dementia with Lewy bodies with about 10-15% of all dementias: protein deposits, so-called Lewy corpuscles, are found in cerebral cortex pathology. Besides memory impairment, patients often present detailed optical perception disorders (“visitors”), fluctuating impairments of mental abilities and alertness during the course of the day and motor symptoms of Parkinson’s disease.
  • Fronto-temporal dementia: Fronto-temporal dementia is a rare form of dementia (5%) and tends to affect younger patients (around the age of 50). This form of dementia is caused by shrinkage of the frontal or temporal lobe. Typical is a change in character and a disturbance in the processing of emotions. In special cases there may be an isolated, slowly progressing loss of speech (aphasia).
  • Other causes: alcohol and drugs abuse (Korsakoff-syndrome), brain tumor, brain trauma, vitamin B12 deficiency, HIV infection, hypothyroidism.

Despite over a century of research and technique progress, the accurate diagnosis of the cause of dementia remains challenging. Furthermore, some patients can present an overlap of two or three diseases (for example: AD + vascular dementia). However, the earlier diagnosis of Dementia is very important, since many preventive measures can be taken to avoid the development and progression of symptoms.


World Health Organization: Factsheets Dementia

van der Flier, W. M. and Scheltens, P. (2005) ‘Epidemiology and risk factors of dementia’, Journal of Neurology, Neurosurgery & Psychiatry, 76(suppl 5), p. v2 LP-v7. doi: 10.1136/jnnp.2005.082867.