Depression is also a pathology of memory.
Admittedly, sadness, loss of vital momentum, suicidal thoughts, feelings of anxiety, fatigue, lack of appetite, sleep disorders and psychomotor slowing... are characteristic of this disease marked by the diversity of symptoms and varying degrees of severity.
But very often, it is also accompanied by attention disorders and more or less significant memory problems.
If they are functional, and not irremediable, they participate in maintaining recurring negative thoughts and illness.
On average around the world, 2-21% of people have experienced or will experience a major depressive episode in their lifetime – the lowest figures for China, and the highest for countries Europeans – notably from France.
In recent months, in the context of a pandemic, they have unsurprisingly been on the rise: according to a survey by the DREES (Research, Studies, Evaluation and Statistics Department) published last March, at the After the first confinement, 13.5% of people aged 15 and over living in France had a depressive syndrome, an increase of 2.5 points compared to the previous year.
The main danger of depression is naturally the risk of acting out.
"There are just under 9,000 suicides a year in our country, a third of which are from the over 65s",
underlines Véronique Lefebvre des Nöettes, psychiatrist for the elderly in Limeil-Brévannes (AP-HP).
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By affecting attention and memory, depression can have cognitive repercussions and seriously limit, if not to say obstruct, the apprehension of the past, the present, but also of the future.
“Memory is built in connection with the image that we have of ourselves.
In general, we all have an optimism bias that pushes us towards a rather positive narrative of ourselves and the world around us, which allows us to move forward by projecting ourselves into a very open future. ,
specifies the neuropsychologist Francis Eustache, in charge of a research unit dedicated to the study of human memory in Caen.
“However, in the event of a depression, this optimism bias is not present, and the horizon is on the contrary completely blocked.
»
Concentration disorders
As his team showed a few years ago by focusing on anxiety – frequently correlated with depressive symptoms – everything depends on the intensity of the disorder.
The researchers proposed to a few thousand people aged 65 and over (without signs of dementia) to complete a questionnaire to assess their anxiety state: without anxiety, with mild, moderate or intense anxiety.
Then they had them take tests to assess their cognitive functioning and any associated memory problems.
Results: Mild anxiety had no effect;
the moderate level could have a positive effect;
but intense anxiety was negative for working memory.
In his consultations, Dr. Lefebvre des Noëttes observes in his depressive patients
"anhedonia (loss of vital momentum), athymhormia (loss of motivation), aboulia (loss of will), and all kinds other symptoms”.
She observes that
“the memory problems they complain about are often problems with attention and concentration.
These are dysexecutive disorders,
continues the psychiatrist,
that is to say difficulties that the brain, and more precisely the frontal lobe, has in carrying out two tasks simultaneously ”.
Beyond the short-term effects, it is the memory of the self, that which does not benefit from the bias of optimism, which is affected in depressives.
Adobe
For the depressed person, it therefore becomes complicated to reason, plan, remember certain events and talk about them, or to understand what they read and what they are told.
There is no question here of a deficit in the encoding of information.
“It is rather a problem of recall, and more precisely of free recall,
explains Dr. Lefebvre des Noëttes
: as soon as you give a clue, the memorized information comes back to the patient.
»
Beyond the short-term effects, it is the memory of the self, that which does not benefit from the bias of optimism, which is affected in depressives.
Arnaud D'Argembeau, researcher at the psychology and cognitive neurosciences unit of the University of Liège details.
First, there are memories that lack precision.
"If a depressed person is asked to remember the last birthday they were invited to, they will answer, for example,
'I don't have fun at birthday parties'
, rather than talking about a memory going back on a particular day, in a particular place, with such another person.
»
The second striking aspect of the dysfunction of this autobiographical memory is that it focuses more on negative memories, which are both more numerous in free recall, and which come back more quickly than the others with the help of clues.
Finally, these disorders are also combined in the future, complicating any time travel.
Also, when positive memories are retrieved, they will not necessarily warm the heart of the depressed person.
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Added to this already heavy picture are intrusive memories linked to negative events (mourning, illness, break-ups, etc.), as in post-traumatic stress syndrome.
In addition, the depressed person's attention is focused on negative experiences, and situations are interpreted in a negative way.
As Francis Eustache points out,
“all this contributes to fueling negative representations of oneself, of the world and of the future”.
This gloomy loop can however be broken as long as the depressed person consults and is taken care of.
Good to know
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The management of depression
is based on the combination of drug treatment aimed at boosting neuromediators (dopamine, serotonin, norepinephrine) and psychotherapy.
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According to the DSM-5
(reference for psychiatric professionals in the United States), there is depression if 5 symptoms are noted in a list of 9 (with necessarily sadness and/or loss of interest and pleasure) for 15 days, and whether they have an impact on personal, professional and social life.
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Elderly people
rarely say they are sad and complain little about the lack of pleasure, the number of them suffering from depression is underestimated: a survey by epidemiologist Sylvaine Artero showed that in Montpellier, it was necessary to multiply numbers of depressed elderly by five!