Alzheimer's disease is a neurodegenerative disorder which was discovered by Aloïs Alzheimer in 1906. It causes a gradual loss of neurons, which are the brain's basic functional units used to programme various actions such as memory, language and reasoning.
Neuron deterioration causes problems relating to memory, cognitive functions and behaviour. The onset of symptoms is generally slow with symptoms becoming more severe over time. As a result, people affected by the disease gradually lose their independence.
Although Alzheimer's disease is more common among elderly people, it is not a normal consequence of ageing.
No treatment has yet been developed to tackle the cellular mechanisms of the disease. Current treatments are not curative and do not impede neuron degeneration and death, although they can slow symptom progression.
Four such drugs are currently marketed. Their molecules act by preventing the destruction of neurotransmitters which enable information to be transmitted between neurons in certain parts of the brain.
Controlled trials have shown moderate yet significant improvements in cognitive functions, everyday activities and general judgement in patients as reported by their families and physicians.
a) Healthy brain b) Brain in the advanced stage of the disease
c) The two brains overlaid
Illustration: Jannis Productions. Rebekah Fredenburg, computer animation; Stacy Jannis, illustration/artistic direction.
Ninety percent of what we know about Alzheimer's disease has been discovered over the past two decades.Although researchers have shed light on the mechanisms that cause the lesions to form, they have not yet explained why they occur. The exact cause of the disease is therefore still not known.
However, certain risk factors have been identified:
It is completely normal to occasionally forget appointments, a colleague's name or a telephone number. However, if several disorders combine to impact significantly on a person's life, this should prompt both the individual and their family to consider the possibility of Alzheimer's disease.
The disorders associated with Alzheimer's disease are:
Do not ignore these signs. Go and see a physician to determine the cause.
Although no preventive treatment has been developed for the disease, researchers are examining various potential strategies for protecting against it and slowing its progress.
Various studies have examined the impact of specific diets on Alzheimer's prevention. In particular, several observations have been made regarding the Mediterranean diet which largely consists of fish, fruit, vegetables and olive oil. For example, it has been noted that subjects who eat fish twice or three times a week reduce their risk of declining cognitive function. Although this is a promising potential preventive strategy, it needs to be backed up by more robust long-term studies.
Physical and mental activity
Physical rather than sporting activity is cited as a potential preventive strategy. Naturally, physical exercise is recommended for people of all ages, whether by taking walks or using the stairs instead of taking the lift. Although this constitutes a good preventive strategy, it is not unique to Alzheimer's disease.
As regards mental activities, there is evidence to suggest that risk is reduced by engaging in exercises that stimulate memory, logic or thought. However, this theory is also still being scientifically tested.
There are two prevailing assumptions regarding protective factors – one relating to cognitive reserve (whereby the more neuron networks are developed, the longer the onset of symptoms is delayed) and the other to vascular lesion prevention.
In terms of cognitive reserve, increased brain activity is recommended.
In terms of vascular lesions, people are advised to control their blood sugar, blood pressure and cholesterol.
Hopes for research
To date, studies have identified the most critical factors in Alzheimer's disease, namely patients' level of education, diabetes, fruit and vegetable intake and genetic aspects. However, it is too early to confirm a causal link with these factors. This remains to be proven by epidemiological and clinical trials. Although work is under way,it is likely that we will have to wait five to ten years before more tailored prevention can be offeredand specific recommendations made.