Persistent/chronic peer victimization affects around 10% of children and adolescents who find themselves the targets of negative peer behavior, such as physical abuse or name-calling, usually in school. These children are more likely to exhibit symptoms of depression (for example, feeling sad, or having a negative outlook on life) than children who are not victimized by their peers. In our research, my colleagues and I have found that the body’s response to stress in the moment of a negative experience may shed light on the link between victimization and depression. Our findings can help clarify the biological connections between negative peer experiences in childhood and the development and persistence of depression. 

“Study after study has shown that being victimized by peers is linked to self-reports of depression.”

Although many children have returned to in-person instruction following pandemic-related closures, there are lingering concerns about their mental health, given the amount of time they spent outside of school during the COVID pandemic and its lingering impact. One pernicious challenge that many children face in school is harassment from their peers. Study after study has shown that being victimized by peers is linked to self-reports of depression. What’s less clear though, is exactly what processes explain this association. To better understand these links, we used a methodological approach called experience sampling, which captures people’s feelings in the moment.

In our recently published study using this approach, over 100 children aged 10-11 were asked to fill out a short diary five times a day over four school days, including a measure indicating how negative their experiences with peers were at that moment. At the same time, they provided us with a sample of their saliva that allowed us to measure the level of cortisol in their bodies. Cortisol is a hormone implicated in our body’s “fight or flight” stress response.

“Kids who were chronically victimized were more likely to have a dampened physiological response to negative experiences in the moment, and to report depressive symptoms.”

Separately, these children also reported whether they felt they were being victimized by their peers and responded to questions measuring their level of depression. We used these data to disentangle the factors involved in the association between peer victimization and depression above and beyond the strength of children’s stress responses in the moment. For most of the children in our study, more peer victimization was related to higher cortisol reactivity – suggesting that being victimized felt stressful. However, the 10% of children who reported that they were often or always victimized by peers showed a decrease in their cortisol response to negative experiences. This “hypo-corticotropic” response has been observed in abused animals, also in victims of domestic violence and reflects an adaptive response to repeated, acute stress. It is also present in stably depressed individuals.

Accordingly, kids who were chronically victimized were more likely to have a dampened physiological response to negative experiences in the moment, and to report depressive symptoms. This suggests two things. First, people differ in their immediate physiological responses to negative experiences. More importantly, these differences may help to explain the connections between negative social experiences (such as victimization) and mental health (as reflected in symptoms of depression).  

“Our findings suggest that interventions aimed at reducing harassment or bullying in schools must consider students’ feelings of stress at the moment when a negative experience happens.”

There is a consistent link between being picked on by classmates during childhood and measures of depression, and the repercussions can sometimes last into adulthood. Our findings suggest that interventions aimed at reducing harassment or bullying in schools must consider students’ feelings of stress at the moment when a negative experience happens. Many current interventions focus on developing social skills, which are hugely important, but it appears that they are only part of the equation. Our study provides evidence that the far-reaching effects of negative peer experiences may be rooted in the body’s physiological system that deals with situational stress. Helping students process their responses to negative peer experiences as they occur may ultimately reduce symptoms of depression over the lifespan.

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