A patient with Alzheimer’s disease in the Village Landais Alzheimer in Dax, southwestern France, on September 9, 2020 ( AFP / Philippe LOPEZ )
Causing progressive memory loss, Alzheimer’s disease, which is Wednesday the world day, affects more than 30 million people in the world and still remains without curative treatment.
– What is Alzheimer’s? –
Described for the first time in 1906 by the German doctor Alois Alzheimer, this “neurodegenerative” disease leads to a progressive deterioration of cognitive abilities leading to a loss of autonomy for the patient.
Symptoms include repeated forgetfulness, orientation problems, executive function disorders (planning, organizing, ordering in time, having abstract thoughts) or language disorders.
– How many patients? –
According to the World Health Organization (WHO), more than 55 million people in the world suffer from dementia, a set of which Alzheimer’s disease is the most widespread form: the latter accounts for 60 to 70% of cases of dementia. dementia, i.e. more than 30 million sufferers.
The number of people affected is expected to triple by 2050, due to an increase in cases in low- and middle-income countries, according to the WHO.
This explosion will further increase the societal burden, already heavy of this disease, for the relatives of the patients and for the health systems.
A nursing assistant helps an elderly resident, suffering from Alzheimer’s, in a house in L’Hay-les-Roses, in the Paris suburbs, on February 17, 2022 ( AFP / ALAIN JOCARD )
Already today, Alzheimer’s and dementia are among the leading causes of disability and dependency for the elderly.
– What are the causes? –
Alzheimer’s disease may be the most common dementia, but its precise causes and mechanisms are still largely unknown.
Two phenomena are systematically found in Alzheimer’s patients. On the one hand, the formation of so-called amyloid protein plaques, which compress the neurons and eventually destroy them.
On the other hand, a second type of protein, called Tau, present in neurons forms, in patients, clusters which also end up causing the death of affected cells.
But it is not yet clear how these two phenomena are linked. It is also largely unknown what causes their appearance and even, to what extent they explain the course of the disease.
The assumption, long dominant, that the formation of amyloid plaques is systematically a triggering factor and not the consequence of other mechanisms is increasingly being called into question.
– What are the remedies? –
This is largely the consequence of the difficulties in finding the triggers of this disease: despite decades of research, no treatment today can cure or even prevent the onset of the disease.
Main advance for 20 years, a treatment of the American laboratory Biogen, which targets amyloid proteins, obtained some results and was approved for certain cases by the American authorities. But its effects remain limited and its therapeutic interest is discussed.
– Which risk factors, which prevention? –
According to Inserm, the main risk factor is age: the risk of occurrence of Alzheimer’s disease increases after 65 years and explodes after 80 years.
Cardiovascular risk factors such as diabetes or hypertension, when not taken care of in middle age, are also associated with a more frequent occurrence of the disease, although we do not yet know by what mechanisms.
Patients taking part in a physical activity workshop at the Village Landais Alzheimer in Dax, southwestern France, on September 9, 2020 ( AFP / Philippe LOPEZ )
A sedentary lifestyle is another risk factor, as well as cranial microtraumas observed in certain athletes (such as rugby players or boxers).
Conversely, the fact of having studied and having had a stimulating professional activity as well as an active social life, seems to delay the appearance of the first symptoms and their severity.
Under these conditions, the brain would benefit from a “cognitive reserve” which makes it possible to compensate, at least for a time, for the function of the lost neurons. This effect would be linked to cerebral plasticity, namely our brain’s ability to adapt.