The National Child Traumatic Stress Network (NCTSN), which is funded by the U.S. Department of Health and Human Services, explicitly defines bullying as a form of trauma with deep roots:

Bullying is a form of trauma exposure… Repeated experiences of rejection, humiliation, fear, and isolation can leave profound psychological scars. For many children, the impact can remain long after the bullying itself has stopped, altering their self-concept, relationships, and health into adulthood.

A landmark, decades-long study led by Duke University Health System tracked victims of bullying from childhood into adulthood. Dr. William Copeland, a lead researcher on the project, summarized the findings perfectly:

Bullying is not just a harmless rite of passage or an inevitable part of growing up. We found that childhood bullying can cause severe, lifelong psychological damage, leaving victims at a significantly higher risk for anxiety disorders, depression, and panic attacks well into their adult lives.

The Anti-Bullying Alliance, documents both the short- and long-term effects of bulling.

The short-term effects. Children and young people who have experienced bullying are more likely to:

• Face barriers to learning
• Miss school (Natcen research found that at any one time over 16,000 young people aged 11-15 are missing education primarily due to bullying)
• Be excluded (children that were bullied daily were 3 times more likely to be excluded from school than those that were not bullied)
• Retaliate
• Place strain on families/careers
• Self harm and experience depression
• Have impaired wellbeing

The long-term effects. The Anti-Bullying Alliance also documents that the damage spans a lifetime:

We now recognize that the impact of childhood bullying victimization is not a temporary phase. It acts as an adverse childhood experience that independently contributes to adult mental health issues, lower self-esteem, and social withdrawal. The psychological and physical scars can persist up to midlife and beyond.

Writing on the lifetime neurological and emotional lock of childhood trauma, Dr. R. Brian Salinas, Psy.D., a clinical mental health professional and professor, summarized the lifespan impact directly:

In the grand scheme, the impact of bullying does not end once the bullying stops. The effects of the trauma can follow the victim for the rest of their lives. It can create a world where the victim feels disempowered and disenfranchised… Unless dealt with, all trauma lives on in the minds of the victims, even those whose trauma is that of bullying.

Acclaimed educator and author William J. Rossi, who worked in residential treatment facilities with youth suffering from PTSD, describes how an inner chaos incapacitates traumatized youth:

A traumatized person suffers depression, anxiety, and numbness. Trauma brings fear of life and an inner chaos that produces anxiety as he loses control of his life. This stimulates an impulse to escape in order to find relief and protection which in turn renders him incapable of filling his basic human need of creating order in his personal world.