Amnesia is defined as a difficulty in forming memories or retrieving information in memory. Often pathological, it can also be non-pathological, as in the case of infantile amnesia. It is, in fact, more a symptom than a disease, mainly linked in our aging societies to neurodegenerative pathologies such as Alzheimer’s disease, and can have several other etiologies. Amnesia can for example also be of psychogenic or traumatic origin. One of the possible treatments is memory rehabilitation, which can be offered even to elderly subjects, in particular in rehabilitation centers.

Definition of amnesia

Amnesia is a generic term, which refers to a difficulty in forming memories, or retrieving information in memory. It can be pathological, or not pathological: this is the case with infantile amnesia. Indeed, it is very difficult for people to recover memories dating back to childhood, but then this is not due to a pathological process.

Amnesia is more of a symptom than a disease in itself: this symptom of memory impairment can be a sign of a neurodegenerative disease, the most emblematic of which is Alzheimer’s disease. In addition, amnesic syndrome is a type of memory pathology in which memory disorders are very important.

There are several forms of amnesia:

• a form of amnesia in which patients forget part of their past, called identity amnesia, and the intensity of which is variable: the patient can go so far as to forget his personal identity.
• anterograde amnesia, which means that patients have difficulty acquiring new information.
• retrograde amnesia is characterized by forgetting the past.

In many forms of amnesia, both sides, anterograde and retrograde, are present, but this is not always the case. In addition, there are also gradients. “Patients are all different from each other, notes Professor Francis Eustache, professor specializing in memory, and this requires a very precise excursion in order to fully understand the troubles involved.«

Causes of amnesia

In fact, amnesia is caused by many situations in which the patient has memory impairment. The most common are the following:

• neurodegenerative disorders, the best known of which is Alzheimer’s disease, which is a growing cause of amnesia in today’s societies which are evolving towards an overall aging of the population;
• head trauma;
• Korsakoff syndrome (a neurological disorder of multifactorial origin, characterized in particular by impaired cognition);
• brain tumor ;
• sequelae of a stroke: here, the location of the lesion in the brain will play a major role;
• Amnesia can also be associated with cerebral anoxia, following cardiac arrest for example, and therefore a lack of oxygen in the brain;
• Amnesias can also be of psychogenic origin: they will then be linked to functional psychological pathologies, such as emotional shock or emotional trauma.

Diagnosis of amnesia

The diagnosis depends on the general clinical context.

• For a head trauma, after a coma, the etiology of the amnesia will be easily identified.
• In many cases, the neuropsychologist will be able to help with the diagnosis. Usually, memory exams are done through questionnaires, which test memory efficiency. An interview with the patient and those around him can also contribute to the diagnosis. More broadly, the cognitive functions of language, and of the sphere of cognition, can be assessed. 
• A neurological examination may be performed by a neurologist, via the clinic, in order to examine the patient’s motor disturbances, his sensory and sensory disturbances, and also to establish a memory examination in a larger context. An anatomical MRI will allow visualization of any lesions. For example, MRI will make it possible, after a stroke, to see if lesions exist, and where they are located in the brain. Damage to the hippocampus, located on the inner side of the temporal lobe of the brain, can also cause memory impairment.

The people concerned

Depending on the etiology, the people affected by amnesia will not be the same.

• The most common people affected by amnesia caused by a neurodegenerative disorder are the elderly.
• But cranial traumas will affect young people more, following motorbike or car accidents, or falls.
• Cerebrovascular accidents, or strokes, can also affect young people, but more often affect people of a certain age.

The major risk factor is age: the older a person, the more likely they are to develop memory problems.

The symptoms of the different types of amnesia can take very different forms, depending on the types of pathologies involved, and the patients. Here are the most common.

Anterograde amnesia

This type of amnesia is characterized by a difficulty in acquiring new information: the symptom is therefore manifested here by a problem in retaining recent information.

Retrograde amnesia

A temporal gradient is often observed in this form of amnesia: that is to say that, in general, patients suffering from amnesia will rather censor their most distant memories, and on the contrary well memorize more recent memories. .

The symptoms manifested in amnesia will depend heavily on their etiology, and therefore will not all be treated in the same way.

Currently, drug treatments in Alzheimer’s disease depend on the stage of severity of the pathology. The drugs are mainly for delay, and taken at the beginning of the evolution. When the seriousness of the pathology worsens, the management will be more socio-psychological, within structures adapted to these people with a memory disorder.

In addition, a neuropsychological type of care will aim to exploit the capacities preserved in the disease. Contextualized exercises may be offered, within appropriate structures, such as rehabilitation centers. Re-educating memory is an essential point in the care of amnesia, or memory impairment, at any age and whatever the cause.

There are reserve factors, which will help protect the person from the risk of developing a neurodegenerative disease. Among them: factors of hygiene of life. It is thus necessary to guard against diseases such as diabetes or arterial hypertension, which interact strongly with the neurodegenerative aspects. A healthy lifestyle, both nutritionally and through regular physical activity, will help preserve memory.

On a more cognitive aspect, the notion of cognitive reserve has been established: it is strongly based on social interaction and level of education. It is about keeping intellectual activities, participating in associations, traveling. “All these activities that stimulate the individual are protective factors, reading is also one of them.“, Emphasizes Francis Eustache.

The professor explains thus, in one of his works that “if two patients present the same level of lesions reducing their cerebral capacities, patient 1 will present disorders while patient 2 will not be affected cognitively, because his cerebral reserve gives him a greater margin, before reaching the critical threshold of functional deficit“. In fact, the reserve is defined “in terms of the amount of brain damage that can be tolerated before reaching the threshold of clinical expression of the deficits«.

• In this so-called passive model, this structural brain reserve thus depends on factors such as the number of neurons and connections available.
• A so-called active reserve model takes into account the differences between individuals in the way they perform tasks, including in their daily life.
• In addition, there are also compensation mechanisms, which will make it possible to recruit alternative brain networks, other than those usually used, in order to compensate for brain damage.

Prevention is not an easy task: the term prevention means more, for the American author Peter J. Whitehouse, doctor of medicine and psychology, “delay the onset of cognitive decline, or slow its progression, rather than completely eliminating it“. A major issue of the present day, since the annual report of the United Nations on the world population indicated in 2005 that “the number of people aged 60 and over is said to have nearly tripled by 2050, reaching nearly 1,9 billion people«. 

Peter J. Whitehouse proposes, with his colleague Daniel George, a prevention plan, with the aim of preventing cerebral aging at the base of neurodegenerative diseases, based on:

• on diet: eat less trans and saturated fats and processed foods, more fish and healthy fats such as omega 3s, less salt, reduce your daily calorie consumption, and enjoy alcohol in moderation; 
• on the sufficiently rich diet of young children, in order to protect their brains from an early age;
• exercising for 15 to 30 minutes a day, three times a week, choosing activities that are pleasant to the person; 
• on avoiding environmental exposures to toxic products such as ingesting high-toxin fish, and removing lead and other toxic substances from the home;
• on stress reduction, by exercising, relaxing leisure activities, and surrounding yourself with calming people;
• on the importance of building up a cognitive reserve: engaging in stimulating activities, doing all possible studies and training, learning new skills, allowing resources to be distributed more equitably in schools;
• on the desire to stay in shape until the end of one’s life: by not hesitating to seek the help of doctors or other health professionals, by choosing a stimulating job, learning a new language or by playing a musical instrument, playing board or card games in a group, engaging in intellectually stimulating conversations, cultivating a garden, reading intellectually stimulating books, taking adult classes, volunteering , maintaining a positive outlook on existence, defending his convictions;
• on the fact of protecting oneself against infections: avoiding infections in early childhood and ensuring good health care for oneself and one’s family, contributing to the global fight against infectious diseases, adopting behaviors to fight against global warming .

And Peter J. Whitehouse to recall:

• the modest symptomatic relief provided by current pharmacological treatments in Alzheimer’s disease;
• systematically discouraging results provided by recent clinical trials on new treatment proposals;
• uncertainties regarding the possible merits of future treatments such as stem cells or beta-amyloid vaccines.

These two doctors and psychologists advise governments to “feel motivated enough to start pursuing a nuanced policy, which would aim to improve the health of the entire population, throughout people’s lives, rather than responding to cognitive decline after the fact«.

And Peter Whitehouse finally quotes Arne Naess, a former professor at the University of Oslo where he coined the term “deep ecology”, expressing the idea that “human beings are intimately and spiritually linked to the earth“:”Think like a mountain!“, Mountain whose eroded sides communicate a feeling of slow modification, like the reflection of the natural processes of aging, and whose peaks and their summits motivate to elevate one’s thinking…