Dementia may be defined as a global deterioration in intellectual function, behaviour and personality in the presence of normal consciousness and perception.

The most common causes of dementia are age-related neurodegenerative processes. Dementia is becoming an increasing problem as the population ages.

Many causes of dementia are irreversible and so the diagnostic emphasis is placed on detecting the treatable subgroup of patients.

• Alzheimer's disease is the cause of most cases of dementia, accounting for about 60% of all cases
  • is a degenerative cerebral disease, with insidious onset, which is characterised by a slow progressive decline in cognition and ability to function
• vascular dementia and dementia with Lewy bodies (DLB) are responsible for most other cases of dementia, although mixed cases (e.g. Alzheimer's disease and vascular dementia) are commonly encountered, especially in older people
  • vascular dementia usually arises from multiple infarcts or generalised small vessel disease - has a more sudden onset than Alzheimer's disease.
  • DLB is slowly progressive - DLB shares many of the features of Alzheimer's disease and Parkinson's disease
• dementia also develops in about 30% to 70% of people with Parkinson's disease

Reference:

• (1) MeReC Bulletin 2007;18 (1).