Last edited 05/2022
Alzheimer's disease (AD) is a progressive degenerative disease of the brain and is considered the most common cause of dementia (1).
It may be defined as a clinicopathological entity where there are histological changes of neurofibrillary tangles and senile plaques in a patient with dementia (1).
An informative history is therefore very important.
- Alzheimer's disease is usually insidious in onset and develops slowly but steadily over a period of several years
- affects predominantly the elderly
- progression is characterised by deterioration in cognition (thinking, conceiving, reasoning) and functional ability (activities of daily living) and a disturbance in behaviour and mood
- evidence suggests that Alzheimer's disease progression is dependent on age, and the time from diagnosis to death is about 5–20 years (median 5 years in people aged 75–80 years)
- people with Alzheimer's disease lose the ability to carry out routine daily activities like dressing, toileting, travelling and handling money and, as a result, many of them require a high level of care
- non-cognitive symptoms in dementia include agitation, behavioural disturbances (for example, wandering or aggression), depression, delusions and hallucinations.
Mental State Examination (MMSE – 30 points) can be used to classify the severity of cognitive impairment in Alzheimer's disease (2):
- mild Alzheimer's disease: MMSE 21 to 26
- moderate Alzheimer's disease: MMSE 10 to 20
- moderately severe Alzheimer's disease: MMSE 10 to 14
- severe Alzheimer's disease: MMSE less than 10.
The diagnosis requires confirmation at post-mortem, although in practise it is made on clinical grounds.