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RTD info logoMagazine on European Research Special Issue - April 2005   
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NEURODEGENERATIVE DISEASES
Title  From forgetfulness to dependency

Alzheimer’s. Previously ignored, today the very word spells fear. It is a disease that affects nearly 5 million Europeans and which is growing at the rate of 800 000 a year. Despite this, scientists still understand little about the processes that produce this fatal neuron degeneration. The European Alzheimer's Disease Consortium (EADC), a network of 50 centres of excellence, is one of the first global networks to combat the disease on the two fronts of prevention and therapeutic research.

Alzheimer’s disease: senile plaques in the cerebral cortex. © INSERM/E.Hirsch
Alzheimer’s disease: senile plaques in the cerebral cortex.
© INSERM/E.Hirsch
"Whether you are talking about Alzheimer’s disease(1) or other neurodegenerative diseases, such as fronto temporal dementia or Lewy body disease, the common point is the irreversible deterioration and death of neurons in the regions of the brain that are involved in memory and learning,” explains Bruno Vellas, a Professor of internal medicine and geriatrics at Toulouse University Hospital (FR) and the coordinator of the EADC network. “When these neurons meet other cells, they are no longer able to divide and, thus, never regenerate.”

We know little about the causes of Alzheimer’s and, while some specialists regard it ‘simply’ as a pathological variation of ageing, others stress a genetic predisposition linked to the role of the gene coding for apolipoprotein E (ApoE), which provides neurons with their cholesterol needs. For a variant that strikes early in life, chromosome 14 is the suspected culprit. Environmental factors, such as an excessively rich diet or sedentary lifestyle are also raised as possible factors. As for the phenomenon of degeneration itself, after previously being divided on which of two processes was at work, scientists today acknowledge the significance of both: the presence of deposits (plaques, especially of beta-amyloid proteins) between the neurons, in the grey matter of the cortex; and the invasion of the latter by neurofibrillae, microscopic fibres that mainly consist of the protein tau. 

Building momentum
“The main motivation for setting up the EADC was to share knowledge so that we can progress faster and better,” notes its coordinator. “To this end, specialists from various backgrounds – fundamental researchers and practitioners, neurologists, geriatricians, psychiatrists, etc. – agreed to work on common protocols governing the criteria for diagnostics, evaluation tools, data collection methods, etc. At the same time, various working groups are analysing therapies, genetics, cognitive function, medical imaging, and behavioural problems. The EADC also co-operates actively with the Alzheimer’s comparative study, which is, in a way, our counterpart in the United States. We learn from each other’s successes and failures.”

A maximum of scientific co-operation is most certainly warranted in combating this most harrowing of diseases, which brings real suffering to the patient and his or her loved ones. It leads inevitably to a state of total dependence that can be of long duration. The disease’s social cost in Europe is equivalent to that of cardiovascular disease and cancer combined. The European Union is currently supporting two EADC research projects focusing on preventing and treating the disease. 

Prevention is possible
"Tests and procedures are now available for more precise diagnoses, as well as treatments that can slow the disease’s progress. The Descripa(2) project is currently studying the Mild Cognitive Impairment (MCI) stage, for example. It is estimated that, every year, 15% of people showing MCI symptoms go on to develop Alzheimer’s. Remember that over the last 20 years prevention has brought a significant reduction in vascular disease and that same kind of benefit could apply to neurodegenerative diseases.” 

Known as Ictus(3), the second project that has just been launched by the EADC, is studying the effects produced by treatment with AChE I, the anticholinesterase inhibitors. Some 1 400 European patients at an early stage of the disease who are still living at home will be monitored over a two-year period.

As life expectancy continues to rise, the pharmaceutical industry is also highly motivated by the problem. “Memory drugs are a sector growing at the rate of 20% a year. The day research obtains molecules that really work, European companies plan to be in the running.” This huge market does not, of course, only concern patients. A good memory is a faculty everyone would like to have and sales of gingko biloba extracts, the plant that seems to work as a genuine ‘memory vitamin’, are currently worth a billion dollars a year in the USA. 

(1) The disease owes its name to the German psychiatrist Alois Alzheimer who, in 1906, first identified specific symptoms of this disease of the cerebral cortex in one of his patients, aged 51.
(2) ‘Development of Screening guidelines and diagnostic Criteria for Predementia Alzheimer's disease’.
(3) Impact of Cholinergic Treatment Use.

    
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