The Science Of Childhood Bullying & Adult Mental Health - Dr Tracy Vaillancourt

Here are the top 10 key takeaways from Dr. Tracy Vaillancourt's discussion on childhood bullying, its lasting impact, and the challenges of effective intervention.

1. Power dynamics drive bullying

Bullying fundamentally revolves around power imbalances. Dr. Vaillancourt's research shows that popular children—those with assets the peer group values like attractiveness or athletic ability—are four times more likely to bully others. These high-status bullies use aggression strategically to maintain their social position and establish dominance.

The corrupting influence of power enables bullying to persist. When children achieve social power through valued traits, they often abuse this power to maintain their position. This creates a cycle where power leads to bullying, which reinforces their status. These high-status bullies effectively establish the social norms of the school, influencing how others behave and who becomes acceptable targets.

2. Different types of bullies exist

There are two distinct profiles of bullies. The first is the "Nelson" type (referring to The Simpsons character)—these children have emotional dysregulation issues like ADHD or conduct disorder. They're reactive, less strategic in their aggression, and typically become socially marginalized. Their future outcomes tend to be more negative.

The second and more common type (approximately 90% of bullies) are high-status bullies. These children possess valued social assets—attractiveness, athletic ability, or other competencies—combined with strategic social skills. They blend prosocial and antisocial behaviors, displaying Machiavellian traits and elements of the "dark triad" (narcissism, Machiavellianism, and psychopathy). Despite their bullying behavior, these individuals often achieve success in life precisely because of their social competencies and strategic manipulation skills.

3. Gender differences in bullying methods

Boys and girls typically engage in different forms of bullying. Boys tend to be more direct and obvious in their bullying behaviors, using physical and verbal aggression to establish dominance hierarchies. Their approach is more reactive and focused on putting others "in their place" through direct confrontation.

Girls more commonly use indirect or relational aggression, focusing on social exclusion and relationship manipulation. They spread rumors, give death stares, pretend to be friends to gather information to use against victims, and systematically exclude targets from social groups. These gender differences appear early in development, with girls displaying sophisticated relational aggression as young as age three or four, suggesting these may be evolutionarily shaped strategies.

4. Bullying causes lasting neurobiological damage

The impact of bullying goes far beyond temporary emotional distress—it creates lasting neurobiological changes. Research shows that bullying affects the hypothalamic-pituitary-adrenal (HPA) axis, the body's stress response system. Initially, victims show elevated cortisol levels, but with chronic bullying, the system eventually downregulates, leading to abnormally low cortisol levels.

These biological changes increase vulnerability to future mental health problems, including post-traumatic stress disorder. The effects are measurable decades later, with studies showing that victims still display elevated mental health issues 30-50 years after being bullied. Dr. Vaillancourt emphasizes that bullying also impairs memory function, as elevated cortisol damages areas of the brain rich in glucocorticoid receptors like the hippocampus and prefrontal cortex, directly affecting academic performance.

5. The prevalence and patterns of victimization

Approximately 30% of children experience bullying, with 10% suffering severe, daily victimization. The prevalence equates to hundreds of millions of children worldwide being bullied regularly. Certain characteristics increase vulnerability to victimization, including social withdrawal, neurodivergence (like ADHD), lacking socially valued possessions, and being in a numerical minority within a school environment.

Being overweight is also associated with victimization, but interestingly, Dr. Vaillancourt's research found a bidirectional relationship. Children often gain weight as a consequence of being bullied, creating a destructive cycle where weight gain leads to more bullying. For boys, being thin can trigger bullying due to perceived lack of masculinity, while thin girls may face bullying from other girls due to perceived competitive threat.

6. Current interventions have limited effectiveness

Despite decades of research, bullying interventions show modest results at best. Most interventions achieve only about a 20% reduction in bullying behaviors, with greater success among younger children than adolescents. Programs like KiVa from Finland and Olweus from Norway have shown promising results in their countries of origin but have not translated as effectively to North American or UK contexts.

The most effective approach involves whole-school interventions with multiple components, particularly those that engage bystanders. Dr. Vaillancourt noted that during the pandemic, schools unintentionally achieved a 50% reduction in bullying through increased supervision (implemented for COVID protocols). This finding highlights that simple environmental changes like increased adult supervision in hallways, playgrounds, and other hotspots can be more effective than many formal programs.

7. Moral disengagement enables bullying behavior

Bullies use cognitive strategies to justify their harmful actions—a process called moral disengagement. They convince themselves their victims deserve poor treatment, often through dehumanization, victim-blaming, or diffusing responsibility. These mental mechanisms allow bullies to maintain a positive self-image despite their harmful behaviors.

The problem is compounded because victims often hide their distress due to embarrassment and humiliation. Dr. Vaillancourt's research found that teachers primarily intervene when they observe visible distress in victims. Since victims suppress these signals to avoid further humiliation, the very cue that might trigger intervention or empathy is absent, allowing the bullying cycle to continue unchecked and reinforcing the bully's moral disengagement.

8. Bystander engagement is crucial for intervention

The peer group plays a pivotal role in either enabling or preventing bullying. Since bullying typically occurs in public to establish and maintain power, the reaction of witnesses determines whether the bully's behavior is rewarded with enhanced status or discouraged through peer rejection. Programs that effectively mobilize bystanders to intervene show more promising results than those focused solely on bullies or victims.

However, bystander intervention is complicated by fear. Other children often avoid helping victims because they don't want to become the next target. The high-status bully effectively creates an atmosphere where associating with victims becomes socially toxic. This "social singling" demonstrates consequences for anyone who might challenge the bully's authority, making potential allies reluctant to provide the social support that victims desperately need.

9. The "healthy context paradox" complicates prevention efforts

Dr. Vaillancourt described a counterintuitive finding called the "healthy context paradox." When schools successfully reduce overall bullying rates, the few remaining victims actually experience worse mental health outcomes than before. This occurs partly because the remaining victims make internal attributions about their continued victimization ("there must be something wrong with me") rather than external attributions ("these kids are just jerks").

This paradox presents an ethical dilemma for intervention programs. While reducing bullying benefits the majority, it may inadvertently intensify suffering for a vulnerable minority. This finding highlights the need for targeted support for persistent victims, especially when general bullying rates decrease. Schools must be aware that their success in reducing overall bullying might mask increased vulnerability among those still being victimized.

10. The need to belong drives bullying dynamics

At its core, bullying exploits the fundamental human need to belong. Social exclusion is a powerful tool because humans evolved as social creatures dependent on group acceptance for survival. The peer rejection inherent in bullying triggers profound distress precisely because it threatens this basic need.

Dr. Vaillancourt noted that while interventions may successfully reduce active aggression, they struggle to promote genuine inclusion. Even when overt bullying stops, victims often remain socially isolated. This highlights the limitation of anti-bullying approaches that focus solely on stopping negative behaviors without fostering positive social connections. True prevention requires not just reducing harmful actions but actively promoting a culture of belonging and inclusion to address the deeper social dynamics at play.