A study describes for the first time the brain networks associated with mental ruminations, these repetitive thoughts, and their evolution between the ages of 18 and 22.
This work carried out by the Inserm team “Developmental trajectories in psychiatry” (Inserm/ENS Paris-Saclay) within the Borelli Center for Applied Mathematics[1] also shows an association between rumination brain networks and certain psychiatric symptoms.
The researchers relied on the IMAGEN cohort intended to explore the mental health of young Europeans aged 14 and over. This work, published in the journal Molecular Psychiatryprovides avenues for mental health prevention.
Ruminations are repetitive thoughts, with a feeling of going around in a loop. They frequently appear during the transition from adolescence to the young adult stage, and are linked in particular to the difficulties of entering adult life.
The literature describes three types of ruminations. THE “reflexive” ruminations are not negative; they aim to seek a solution to a problem and can be part of a reflection process (finding housing, a job, etc.). THE “worried” ruminations are linked to complex or conflicting situations, with difficulty in gaining perspective (professional concerns, financial difficulties, etc.). Finally, the third type of ruminations is of a “depressive” with repetitive dark thoughts about his situation or its future.
Common among adolescents, these can be associated with states of anxiety, aggression, depression, or even addictions. Considered as a risk factor of disease psychiatric, they most often precede the appearance of disorders in adulthood. This is why it is important to better understand the brain mechanisms associated with them.
It is with this objective that a team led by Inserm researchers Jean-Luc Martinot and Eric Artiges within the “Developmental trajectories in psychiatry” laboratory was interested for the first time in the brain networks associated with different types of ruminations in during the transition from adolescence to young adulthood.
To this end, the team studied 595 young people included in the European IMAGEN cohort[2] and followed between the ages of 18 and 22 years.
Specific networks associated with ruminations
The young people have passé functional MRIs at rest. This neuroimaging technique makes it possible to follow theactivity spontaneous brain in all regions of the brain.
“During this examination, the subjects had no instructions and were left free to think freely. So the “ruminative” profiles indulged in their ruminations”specifies Jean-Luc Martinot.
These young people also answered questionnaires to measure the frequency and type of their ruminations, and assess the possible presence of psychiatric symptoms.
First, the researchers cross-referenced the imagery and the responses to the questionnaires at age 18, using an innovative mathematical model. This allowed them to associate each type of rumination with the simultaneous activity of two to three specific brain networks.
For example, they showed that at 18 years old, “worried” ruminations were based on brain networks involving the hippocampus and the frontal lobe. “Depressive” ruminations appeared associated with other networks involving the thalamic nucleus and part of the frontal lobe.
Changes at 22
This work was then repeated in these same participants at the age of 22, in order to evaluate how ruminations and associated brain processes evolved over time.
“At this age in their lives, young adults showed a reduction in “worried” ruminations in favor of “reflexive” ruminations.explains Jean-Luc Martinot, this suggests that between the ages of 18 and 22, the transition period to adulthood, they have acquired a better ability to adapt to negative emotions and a better ability to make decisions.“.
This translates concretely at the brain level: by switching from one type of rumination to another, the researchers found that the brain networks activated in the participants were also reshaped.
In the remainder of the study, the team finally showed that the brain networks associated with different types of rumination were also associated with certain psychiatric symptoms. More precisely, the activity of a network associated with worried ruminations was also associated with “internalized” symptoms (anxiety, nervousness, withdrawal, etc.). The activity of a network associated with “depressive” ruminations was also associated with “externalized” symptoms (agitation, irritability, recourse to acting out, to substances, etc.).
“This work reveals links between the evolution of mental ruminations and the evolution of psychiatric symptoms, through functional changes in the brain at the end of adolescence. Two types of ruminations can precede psychiatric symptoms. These data could contribute to the development of preventive approaches among young adults”, concludes Jean-Luc Martinot.
Notes:
[1] The Borelli Center is under the supervision of CNRS/ENS Paris-Saclay/Université Paris-Saclay/Université Paris-Cité/Inserm/Army Health Service.
[2] Co-founded by Jean-Luc Martinot, the IMAGEN cohort is intended to monitor the mental health of adolescents aged 14 and over using psychological, clinical, environmental and brain imaging data.
