Bullying can and does contribute to the development of mental illness. Children who are bullied are roughly twice as likely to develop depression compared to those who aren’t, and the effects can persist for decades. A systematic review covering 28 studies found the odds of experiencing depression up to 36 years after childhood bullying were nearly double (odds ratio of 1.99), even after controlling for other risk factors like family background and socioeconomic status.
The link goes beyond a simple correlation. Longitudinal research, which tracks the same individuals over years, shows that bullying precedes the onset of mental health conditions rather than simply co-occurring with them. One study found that children who experienced bullying were four times more likely to develop severe depression a full decade later.
Which Mental Health Conditions Are Linked to Bullying
Depression is the condition most strongly and consistently tied to bullying victimization. The relationship is bidirectional, meaning bullying increases the risk of depression, and depression also makes a person more vulnerable to further bullying. But the effect of bullying on depression is far stronger than the reverse. Among depressive symptoms, persistent sad mood and sleep disturbances appear to be the key drivers that keep this cycle going.
Anxiety disorders are also common among bullying victims, though the relationship is somewhat more complex. Cyberbullying in particular has emerged as a significant trigger for both depression and anxiety, with research suggesting it may have a more pronounced effect on these conditions than traditional, in-person bullying.
About 37% of bullying victims report significant post-traumatic stress symptoms, including intrusive memories of bullying events, avoidance of places or situations associated with the bullying, nightmares, and a diminished sense of hope for the future. Roughly 25% of victims continue to experience these trauma symptoms even after leaving school, with intrusive memories being the most persistent feature.
Bullying exposure also increases the risk of substance misuse, self-harm, and suicidal thinking. These effects on health and employment can last into early adulthood and even midlife.
Cyberbullying Carries Distinct Risks
A large meta-analysis comparing traditional bullying and cyberbullying found that both significantly increase the risk of mental health problems, but cyberbullying edges ahead in several categories. For depression, the odds are roughly similar: about 3.3 times higher for traditional bullying victims and 3.4 times higher for cyberbullying victims. But for suicidal thinking, the gap widens: traditional bullying raises the odds about 3 times, while cyberbullying raises them about 3.5 times.
The most concerning finding involves young people who experience both forms simultaneously. Those victims face dramatically elevated risks: 5.3 times the odds of depression, 6.6 times for suicidal ideation, and nearly 8 times for suicide attempts compared to non-bullied peers. Bullying rooted in social relationships and networks tends to have a greater psychological impact than physical bullying alone, which may explain why the digital world, where social dynamics play out publicly and constantly, is so damaging.
How Bullying Changes the Brain and Body
Bullying doesn’t just affect how someone feels in the moment. It alters the body’s stress response system. The system that regulates cortisol, your primary stress hormone, can become dysregulated by repeated exposure to peer victimization. Research on adolescents has found that bullying, combined with individual differences in cortisol patterns, is associated with measurable changes in brain structure, specifically in regions of the prefrontal cortex involved in emotional regulation.
In boys, the relationship between bullying and brain development depended on their cortisol profiles. Those who were more biologically sensitive to stress showed reduced surface area in the right prefrontal cortex when they experienced high levels of victimization. This region plays a role in controlling emotional responses, which may help explain why some bullied children struggle more with emotional regulation than others.
At an even deeper level, bullying appears to leave marks on gene expression. A study tracking children across two large cohorts found that bullying exposure was associated with changes in DNA methylation, a process that affects how genes are turned on or off without altering the DNA itself. The changes were concentrated in pathways related to the fight-or-flight response and neurodevelopmental processes like brain cell development and nerve signaling. In non-bullied children, certain genetic markers naturally increased over time, but in bullied children, those same markers decreased, suggesting that bullying literally redirects normal developmental trajectories at a molecular level.
The Effects Can Last Into Old Age
A Swedish study following participants for 10 years found that girls who were bullied had 5 times the odds of psychological complaints during childhood, and nearly 3 times the odds a decade later in their twenties. For boys, the pattern was similar, though slightly less pronounced (3 times the odds during childhood).
The effects extend further than most people would expect. A large Chinese longitudinal study found that older adults who experienced school bullying were still 17% more likely to exhibit depression symptoms decades later. Women, rural residents, and those with less education were hit hardest. A Danish study found that men who recalled being bullied in school were 33% more likely to be diagnosed with depression between ages 31 and 51, even after researchers accounted for social class and parental mental illness.
Not Everyone Who Is Bullied Develops Mental Illness
Despite the strong link between bullying and mental health problems, many bullied children do not go on to develop diagnosable conditions. The difference often comes down to resilience, which isn’t a fixed personality trait but a set of skills and circumstances that can be developed.
The protective factors fall into two categories. Internal factors include self-efficacy, problem-solving ability, emotional intelligence, and the capacity for positive reinterpretation of difficult events. External factors include strong social support, close family relationships, mentorship, and interpersonal skills. Social support is one of the strongest predictors of psychological resilience, while weak social support and isolation are consistently linked to worse outcomes.
Schools that introduce resilience training focused on active coping, help-seeking, humor, and planning have shown promise in buffering the mental health impact of bullying. Programs that build emotional intelligence also appear to strengthen resilience. Anti-bullying intervention programs themselves reduce bullying perpetration by about 19 to 20% and victimization by 15 to 16%, which translates to fewer children being exposed in the first place.
Bullies Are Also at Risk
The mental health consequences of bullying extend to those who do the bullying. Perpetrators face elevated risks of substance use, academic problems, mental health concerns, and suicidality. Bullying behavior tends to peak in middle school and gradually decrease through high school, but the mental health consequences don’t follow the same timeline.
Many adolescents who bully others are themselves dealing with the aftermath of childhood abuse. Research has found that childhood abuse is strongly associated with anxiety, depression, anger, dissociation, and PTSD symptoms, and that anxiety and poor social skills in particular predict bullying behavior two years later. Prior bullying behavior is also the single strongest predictor of future bullying, meaning early intervention matters. Males are somewhat more likely to engage in bullying perpetration, but race and income are not significant predictors.