According to the criteria of DMS5 (5th edition of the manual of diagnosis and statistics of mental disorders), depression is defined as a state of sadness or apathy (loss of envy and/or motivation).
Diagnosis of depression
Ruminants are defined by an inability to “change ideas,” and the patient remains “fixed” on the same negative thoughts.
Our emotions change over time. This may seem obvious, but understanding precisely these variations, their dynamics and the brain regions involved, is of major importance from a therapeutic perspective. Emotional variation is a key characteristic in many mental health disorders such as depression. When you feel emotion, there are two phases. First, the onset of emotion, which can be brutal or progressive, is referred to as the degree of "explosivity" of the emotion. Then the emotional compensation phase, that is, the intensification or attenuation of the emotion over time, assessed by its degree of "accumulation".
The devaluation or “negative affects” in self-perception is often modified, and perhaps even differently in people with suicidal tendencies. There is a correlation between self-perception and depression.
These “negative affects” are often accompanied by a lack of “positive affect,” which translates into an inability to have fun, to have willpower, and to take action.
The latest knowledge in neuroscience suggests that depression is a pathology of motivation, that is, affecting the networks of the brain involved in decision-making and in assessing the cost/benefit of effort.
Indeed, when we have to choose between several actions or decide to make an effort, our decision rests on the respective weight of two elements: benefits, that is, the reward we can obtain or the loss we can avoid, and costs, especially the effort required.
Motivational disturbances are thought to be caused by either decreased reward or loss sensitivity or increased exercise sensitivity. These two mechanisms probably coexist in the same patient to varying degrees. For example, a patient with depression may be unable to join friends for an outing, either because the reward, the pleasure of being with one’s loved ones, is abolished, or because the cost of necessary actions before going out, such as getting ready, getting dressed and going to restaurants, is increased.
At Paris Brain Institute
The team “Cognitive control – interoception – attention” co-led by Philippe FOSSATI and Liane SCHMIDT showed in 2017 that differences in the explosiveness of the triggering of emotion are linked to an activity in the median prefrontal cortex. This region is supposed to be involved in one’s perception of oneself. Here, its activation could therefore reflect the difference between the assessment given by others and the participants’ idea of themselves. Differences in accumulation are related to the activation of the posterior part of the insula, a region known to play a key role in the integration of emotional cues. These findings may have implications for treatment of mental health disorders.
The “Motivation, Brain, and Behavior” team, co-led by Mathias PESSIGLIONE, Jean DAUNIZEAU, and Sébastien BOURRET, is studying apathy and motivation in different ways. Dopamine and noradrenergic neurons play an important role in motivation. Through a behavioural study, researchers have shown that dopaminergic neurons are involved in decision-making, while noradrenergic neurons contribute to the mobilization of energy for action.
This finding is fundamental, as both aspects of behaviour could be targeted preferentially in apathetic patients.
Recently, the same team has identified through intracerebral recordings 4 fundamental properties of brain systems that determine our preferences.
Benedict BATRANCOURT INSERM researcher in the team “FRONTLAB: Functions and dysfunctions of frontal systems”, led by Richard LEVY, led the project ECOCAPTURE, making it possible to measure in natural condition the level of apathy and to specify its form.
Apathy is characterized by a loss of motivation, envy, emotions, and a deficit in the ability to perform and initiate useful behaviours.
It is the most common symptom seen in patients with depression, Alzheimer’s and Parkinson’s diseases. Until now, this syndrome has been little known, poorly elucidated and subjectively evaluated.
This new, simple and objective method of measurement opens the door to studies that correlate the degree of apathy with the course of neurological and psychiatric diseases and measure the effect of treatments on this syndrome.
