summary: The direction of appetite changes associated with depression was linked to specific changes in the brain’s reward system.
Source: Bono University
Major depressive disorders are characterized by a significant health burden, including changes in appetite and body weight. Identifying biomarkers such as changes in brain function to treat depression is difficult because of the varying symptoms of affected individuals.
However, Professor of the University Hospital Tübingen. A research team led by Dr. Nils Kroemer, as well as the University Hospital Bonn (UKB) and the University of Bonn, investigated whether conclusions could be drawn about the direction of changes in appetite—increase or decrease—in the brain’s reward system. Based on the functional architecture of
The results are now being published in the journal Jama Psychiatry,
Depression has many faces. A variety of changes in motivation, emotions, and physical experiences characterize the disorder. Many patients with depression not only lose their desire and interest in rewarding activities, but also lose their appetite.
At the same time, other patients reported increased appetite during the depressive episode. Until now, not much is known about the causes of these differences in depression symptoms and how they can be specifically treated.
A team of researchers led by Professor Dr. Nils Kroemer, who works in the Translational Psychiatry Unit of the Department of Psychiatry and Psychiatry at the University Hospital Tübingen and since 2022 also serves as Professor of Medical Psychology in the Department of Psychiatry and Psychiatry. at the University Hospital Bonn, is now able to gain new insights into this topic as part of a multicentre study.
Using magnetic resonance imaging, the researchers showed that the direction of appetite changes associated with depression is linked to specific changes in the brain’s reward system.
For a long time, Prof. Scientists like Kroemer’s team are exploring shared changes in the reward system in patients with depression. This idea is intuitive because patients with depression usually experience surprising changes in their motivation.
“But the idea of a ‘sad’ reward system appears to be more than an illusion,” explains Kroemer, the study’s lead author.
“Instead of looking for general changes in the reward system, we can better relate specific changes, such as in appetite and body weight, to differences in the brain that help explain individual symptoms.”
about the study
The team of researchers from several German university hospitals examined the brain function of participants affected by rest and recorded their psychotic symptoms. This allowed them to compare whether individual symptoms of depression are more predictable.
To do this, they focused on the functional connectivity (also called connection strength; it describes the strength of communication between different brain regions) of the nucleus accumbens, processing rewards with other brains, and goal-seeking. It is one of the central areas in controlling directed behavior. region.
When patients with depression experienced a loss of appetite during a depressive episode, the strength of the connection between the reward system and other regions that play an essential role in value-based decisions and memory processes was reduced.
If, on the other hand, there was an increase in appetite, the researchers saw a weaker connection between the reward system and the part of the brain where taste stimuli and physical cues are processed.
“These changes in the reward system were so prominent in severe depression that we were able to predict whether someone would suffer from an increase or loss of appetite based on individual profiles of the reward system,” said Kromer, describing the study results. .
“In contrast, it was not possible to tell whether someone had depression in general. Therefore, it is not just a change that matters, but the nature of the behavior change in particular.”
more targeted therapy options
Since there is no universal pattern of changes in the reward system in depression, the study points to the potential of precision medicine. These novel approaches do not focus on a general diagnosis but on individual symptoms.
With the help of such symptom-based changes in the brain, it will be possible to develop more targeted treatments that directly address the specific symptoms of those affected in the future.
For this reason, Kroemer’s research group is planning further studies on improved treatment methods using neuromodulation approaches such as brain stimulation. It aims to investigate how changes in the brain cause certain symptoms and whether they can be reversed using individualized neuromodulatory therapies.
About this depression research news
Author: Press Office
Source: Bono University
contact: Press Office – University of Bonn
image: Image is in public domain
Basic Research: closed access.
Nils B. “Functional connectivity of the nucleus accumbens and changes in appetite in patients with depression” by Kroemer et al. Jama Psychiatry
essence
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Functional connectivity of the nucleus accumbens and appetite changes in patients with depression
importance
Major depressive disorder (MDD) is characterized by a heavy burden on health, including changes in appetite and body weight. The heterogeneity of depressive symptoms has hindered the identification of biomarkers that are ostensibly common to most patients, thus demanding symptom-based mapping.
purpose
To define the enhancement of reward circuit versus decrease in appetite and decrease in body weight in patients with MDD by specifying their contribution and effect on disease biomarkers using resting-state functional connectivity (FC).
Design, setting and participants
In this case–control study, functional magnetic resonance imaging (fMRI) data were derived from the Marburg-Münster for Affective Disorders Cohort Study (MACS) 2107 collected between September 2014 and November 2016. Cross-sectional data of patients with MDD (n = 407) and healthy control participants (n = 400) were analyzed from March 2018 to June 2022.
Main results and measures
Changes in appetite during a depressive episode and their association with FC were examined using fMRI. Taking the nucleus accumbens (NAcc) as the seed of the reward circuit, associations of opposing changes in appetite were mapped, and a sparse trait-specific elastic-net model was created with 10-fold cross-validation went.
Result
Of the 407 patients with MDD, 249 (61.2%) were female, and the mean (SD) age was 36.79 (13.4) years. Decreased NAcc-based FC in the ventromedial prefrontal cortex (vmPFC) and hippocampus was associated with reduced appetite (vmPFC: bootstrap) R= 0.13; 95% CI, 0.02–0.23; Hippocampus: Bootstrap R= 0.15; 95% CI, 0.05–0.26). In contrast, decreased NAcc-based FC in the insular inguinal cortex was associated with increased appetite (bootstrap). R= −0.14; 95% CI, −0.24 to −0.04). Crucially, the cross-validated elastic-net model showed changes in appetite based on NAcc FC and the variance increased with increasing symptom severity (all patients: bootstrap R= 0.24; 95% CI, 0.16–0.31; Patients with a Beck Depression Inventory Score of 28 or higher: Bootstrap R= 0.42; 95% CI, 0.25–0.58). In contrast, NAcc FC did not grade the diagnosis (MDD vs healthy controls).
Conclusion and Relevance
In this study, NAcc-based FC showed significant individual differences in appetite and body weight in patients with depression, which could be leveraged for individualized prediction. However, classification of diagnoses using NAcc-based FC did not exceed probability levels. Such symptom-specific associations emphasize the need to map biomarkers to more limited aspects of psychopathology to improve the classification and treatment of MDD.
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