What is Alzheimer's disease

Alzheimer's is one of a group of neurological diseases which are characterised by progressive dementia without any other neurological signs. It is the commonest cause of dementia in the elderly. Historically, Alzheimer's was used only to describe dementia in relatively young people, those in late middle age, and was thought to be different from the so-called senile dementia. However, it has since been recognised that the characteristic changes in the brain occur regardless of the age of onset of the illness. Alzheimer's is, however, definitely age related. It is uncommon in young people and rare in middle age. However, it is estimated that more than 20% of people over the age of 80 have the disease. The majority of those with Down's Syndrome, however, typically develop the characteristic lesions of Alzheimer's around the age of 40.

For many years now people have noticed that Alzheimer's tends to run in families, suggesting that there is a genetic component to the disease. Recently human apolipoprotein (apo) E has emerged as a major genetic risk factor in Alzheimer's disease. In a number of different populations worldwide, one of the variants of apoE, apoE4, is found more frequently in patients with Alzheimer's than in control groups.

The neuropathology of Alzheimer's involves disruption of the brain protein, amyloid precursor protein. The result of this is that another protein, beta amyloid, known to be toxic to neurons, accumulates into the characteristic tangled plaques that stop the synapses from communicating. With the build up of these plaques, neurons all over the brain are gradually destroyed. This results in a drop of the level of neurotransmitters, and so the gradual, devastating decline in mental functioning and severe memory loss.

How is Alzheimer's disease diagnosed?

Generally, the diagnosis is made on a history of progressive memory loss in an elderly person. Often, there are behaviour changes as well, with excessive emotional outbursts, anxiety and strange behaviour. People who were able to perform day to day activities such as balancing a cheque book can no longer add and subtract, and general functioning deteriorates until eventually the person loses all independence and requires constant care.

Imaging such as CT scan or MRI may be used. But the changes seen in the brain are not specific to Alzheimer's and these investigations have little real function.

It is important to rule out preventable causes of dementia, particularly in the elderly when it may just be accepted as a normal part of aging. Something as simple as depression or disruption in thyroid function can cause dementia. Both are easily treatable. Brain tumours, or chronic subdural heamatomas (a collection of blood causing pressure on the brain) can also cause dementia and may be treatable. Multiple small strokes in the brain may also result in dementia, but unfortunately are not amenable to treatment.

Can we treat Alzheimer's disease?

I'll come to the possible new drug treatments later. At present it is safer to assume that Alzheimer's is untreatable and concentrate on ways of easing the life of both the sufferer and the care givers. As the dementia progresses more care is generally needed, although in many cases, with daily visits from friends or family, even quite a severely demented person can remain independent as long as they are in familiar surroundings. Routine and familiarity are the key to minimising confusion and anxiety. Simple measures such as putting the day and date up on a board will help. Making sure that meals, washing, rising and going to bed are always at the same time will also help. Incontinence and nocturnal wakefullness and wandering are usually the things which really wear down care givers. If at all possible, get 'babysitters' and even go away for periods after admitting the patient for respite care.

You will of course have read in the popular press that there are all sorts of new memory drugs which can either restore memory or slow the progress of the memory loss associated with Alzheimer's. Recent research has identified some of the mechanics of memory and there are some 200 different compounds in various stages of clinical trials for treatment of Alzheimer's. Tacrine can temporarily alleviate memory loss in the early stages by blocking an enzyme which breaks down one vital neurotransmitter. However, it is very poisonous to the liver. There is a similar drug, Acricept, which is less toxic and has been licensed for use in Britain and the USA.

All these drugs show great promise, but a recent report in Time magazine highlighted one of the dangers of such experimentation. An Alzheimer's sufferer involved in clinical trials in the USA was eventually able to remember that she was married. Unfortunately she didn't remember that her husband had died some years previously and waited anxiously for him to return from work each day. This obviously caused daily grief to her and her family.

In South Africa you can contact the Alzheimer's and Related Disorders Association at PO Box 81183, Parkhurst, Johannesburg 2120 for further help and information.

A good site is The Institute of Neurotoxicology and Neurological Disorders. A search for Alzheimer's will lead to numerous other sources of information.