Exposure to bullying as a child was associated with psychiatric disorders in adulthood that required treatment in a study of Finnish children, according to an article published online by JAMA Psychiatry.

Previous research has suggested bullying and exposure to bullying may contribute to later mental health.

Andre Sourander, M.D., Ph.D., of the University of Turku, Finland, and coauthors examined associations between bullying behavior at age 8 and adult psychiatric outcomes by age 29. The study used data from 5,034 Finnish children and assessments of bullying and exposure to bullying were based on information from the children, their parents and teachers. Information on the use of inpatient and outpatient services to treat psychiatric disorders from ages 16 to 29 was obtained from a nationwide hospital register.

About 90 percent of study participants (4,540 of 5,034) did not engage in bullying behavior and, of those, 520 (11.5 percent) had received a psychiatric diagnosis by follow-up. In comparison, 33 of 166 (19.9 percent) of participants who engaged in frequent bullying, 58 of 251 (23.1 percent) participants frequently exposed to bullying, and 24 of 77 (31.2 percent) participants who both frequently engaged in and were frequently exposed to bullying had psychiatric diagnoses by follow-up, according to the results.

Study participants were divided into four groups: those who never or only sometimes bully and are not exposed to bullying; those who frequently bully but are not exposed to bullying; those who were frequently only exposed to bullying; and those who frequently bully and are exposed to bullying.

The treatment of any psychiatric disorder was associated with frequent exposure to bullying, as well as with being a bully and being exposed to bullying. Exposure to bullying was associated with depression, according to the results.

Study participants who were bullies and exposed to bullying at age 8 had a high risk for several psychiatric disorders that required treatment when they were adults.

The authors note the main limitation of the study is the lack of understanding about how bullying-exposure to bullying may lead to psychiatric disorders.

"Future studies containing more nuanced information about the mediating factors that occur between childhood bullying and adulthood disorders will be needed to shed light on this important question. ... Policy makers and health care professionals should be aware of the complex nature between bullying and psychiatric outcomes when they implement prevention and treatment interventions," the study concludes.