Dementia is a progressive illness which affects the brain, and thus memory, thinking and actions. It is a progressive illness and although people of any age may develop it, dementia is more common in older people. Although there are many kinds of dementia, the two most common causes are Alzheimer's Disease and vascular dementia, the latter including multi-infarct dementia.
Alzheimer's Disease damages individual brain cells (neurons) one by one. All neurons are produced by about the mid-point in pregnancy, and the body produces approximately five times the number needed, giving a substantial reserve facility. The normal ageing process over a typical lifespan of 75 years involves the loss of some 30 per cent of neurons, but with 70 per cent remaining this loss will not be apparent.For patients with Alzheimer's Disease the number of neurons starts dropping markedly from about the age of 30, and typically by the age of 70 the number of neurons has fallen below the safety margin of having the 20 per cent available for the brain to function normally. It is only when that degree of neuron loss has occurred that the classic symptoms of Alzheimer's Disease - memory loss, impaired judgement and abstract thinking, and language disturbance, among others - appear.
In the vascular dementia there are problems with the blood supply to brain cells. In multi-infarct dementia, the most common type, tiny strokes (infarcts) damage small areas of the brain, so that the effect on the sufferer is cumulative.
Art work is courtesy of St Andrew's Healthcare patients