Recent research published in Affective Disorders Journal This suggests that teenage girls going through the process of depression anticipate social rejection differently in their brains compared to other girls. Researchers found that certain brain regions involved in threat detection are less able to adapt to repeated social rejection in depressed young people. These findings highlight how this condition can alter the way young brains navigate and learn from negative social interactions.
The teenage years are a sensitive period for social-emotional development, a time when interactions with peers become more important. During adolescence, the brain highly prioritizes social feedback, such as approval or rejection by friends and classmates. Depression during this formative period tends to negatively impact social functioning, changing the way the brain interprets the social environment.
A key brain structure involved in navigating these interactions is the amygdala. This collection of tiny, almond-shaped neurons resides deep in the brain and helps us process emotions and detect threats. The amygdala also attaches importance to social cues, alerting us to certain situations that require an immediate response.
In a typical brain, when exposed to repetitive emotional stimuli, the amygdala exhibits a biological pattern called “habituation.” Habituation means that when a person repeatedly encounters the exact same situation, the brain’s alarm response gradually decreases. When a particular social situation is stable and predictable, the brain conserves energy by reacting less violently.
Previous research suggests that depression can alter the brain’s response to negative emotional information. “Previous research has shown that young people with depression have different neural responses to social cues from their peers,” explained study author Michelle Morningstar, an associate professor of psychology at Queen’s University in Ontario. “For example, depression appears to be associated with heightened neural responses to being accepted or rejected by other teens. This pattern may represent a ‘hypersensitivity’ to feedback from others.”
Less is known about how depression affects this specific process of neural habituation during complex social interactions. The scientists designed the study to see if failure to adapt to repeated social threats could explain some of the social difficulties experienced by depressed teens. “In this study, we aimed to explore how these patterns emerge through interactions with peers,” Morningstar explained.
The authors aimed to uncover potential biological markers of the disease by understanding how the amygdala responds to the threat of rejection over time. “Does the initial rejection response already cause a hyperresponse in areas like the amygdala that are sensitive to salient social information?” Morningstar asked. “Or does this pattern emerge only after repeated rejection by colleagues?”
The research team recruited 76 girls between the ages of 10 and 17. The sample included three distinct groups based on detailed clinical interviews. Twenty-two of the girls had a current diagnosis of major depressive disorder. Thirty girls had no personal history of depression, but were considered to be at familial risk because at least one of their parents had a history of depression.
The remaining 24 girls formed the low-risk control group. This means they have no personal or parental history of mental illness. To measure brain activity, scientists used functional magnetic resonance imaging. This non-invasive scanning technology tracks blood flow in the brain and shows which areas are active during specific cognitive tasks.
While resting in the scanner, the girls participated in a computer-based social assessment task called chatroom interaction. Before the scan, participants looked at photos of other young people and chose a few peers they wanted to talk about theoretically. During the actual brain scan, they were told that they were interacting with two selected peers in a virtual chat room. In reality, a peer was a computer program designed to perform a specific behavior.
During the task, the girls repeatedly predicted whether their hypothetical peers would choose to talk to them about various topics or whether they would decline. One virtual peer was programmed to be mean and rejected participants 67% of the time by placing a large X over their photo. The other peer is programmed to be kind and will accept the participant 67% of the time.
This task included a total of 60 trials divided into average and excellent peers. The researchers focused specifically on the anticipation period during which participants learned their partner’s final decision. This waiting period lasted an average of 4750 ms.
Scientists looked at how activation in the amygdala changed from experiment to experiment as the girls implicitly learned which friends were most likely to reject them. The data showed that in the low- and high-risk groups, brain activity bilaterally in the amygdala steadily decreased across trials involving average peers. Their brains exhibited classic habituation, adapting to the predictable threat of rejection.
“Over time, repeated rejection by virtual peers produced fewer and fewer amygdala responses in youth without depression and in youth at risk for depression (but not currently experiencing depression),” Morningstar told SciPost. Girls with major depressive disorder showed a different biological pattern. The right side of their amygdala showed a much flatter activation slope over time.
“Yet, young people with depression continued to show elevated amygdala responses to repeated peer rejection throughout the task,” Morningstar noted. “In other words, their amygdala was not used to repeated rejection.” This suggests that the depressed girls’ brains continued to respond to mean friends as if the threat of rejection was entirely new each time.
“This finding suggests that the process of social learning about rejection cues may be disrupted in young people with depression,” Morningstar explained. “Unlike their non-depressed peers, whose amygdala became accustomed to repeated rejection, depressed youth continued to show ‘hyperreactivity’ to rejecting peers across multiple trials.”
The researchers noted that this lack of habituation was highly specific to the anticipated social threat situation. Expecting a decision from a kind peer led to habituation, and this biological adaptation did not differ between the three groups. Failures in learning and adaptation at the neural level were uniquely linked to the prediction of negative social outcomes.
The authors also looked at other brain regions to see if this pattern spread throughout the brain. They looked at the anterior insular cortex, an area involved in detecting important information, and the anterior cingulate subcortical cortex, which plays a role in emotional regulation. They found that the anterior insula showed normal habituation across all groups when confronted with average peers.
Furthermore, when anticipating average peer decisions, at-risk girls showed higher overall activation in the anterior cingulate cortex compared to the low-risk group. This provides evidence that genetic risk for depression may increase overall susceptibility to specific emotional domains. Over time, the unique failure to adapt to average peers remained specifically localized to the right amygdala in the group experiencing depression.
It’s important to note that this study measured brain activity, not conscious awareness or explicit learning. The researchers did not assess whether the girls clearly recognized which friends were mean and which were nice, only that their brains no longer adapted to their behavioral patterns. Lack of neural habituation does not automatically mean that a person is consciously preoccupied with social threat.
The study also cannot confirm whether changes in the brain’s habituation cause depression, or whether the experience of depression stops the brain from habituating to social threats. This relationship is likely complex and goes both ways. The sample size of 76 participants was relatively modest for this type of brain imaging study, limiting the researchers’ ability to investigate how other individual differences influence the learning process.
For example, scientists could not easily measure how baseline anxiety or general fear of social situations changed a particular participant’s brain activity. The study was also limited to adolescent girls assigned female at birth. Because different demographic groups may process social information differently, the results cannot be generalized to boys, adults, or individuals with other gender identities.
Future research will need to investigate how different brain regions communicate with each other during these social tasks. Brain structures do not function in isolation, and depression can affect broader networks that manage emotions and social behavior. Linking these neural patterns to actual social behavior in daily life will help reveal how changes in social learning contribute to adolescent mental health.
The study, “Decreased amygdala habituation to anticipation of social rejection in youth with major depressive disorder,” was authored by M. Morningstar, MNK Gravelle, DP Dickstein, JS Silk, RE Dahl, EE Nelson, D. Yee, and LR Stroud.
