A study of twins found that those who were bullied were much more likely to suffer "internalizing" mental-health problems such as depression and anxiety than their non-bullied brothers or sisters, Reuters reported Feb. 6.

Researchers led by Louise Arsenault of King's College in London studied children who had been bullied between ages 7 and 9 and assessed their mental health at age 10. The study involved 1,116 twin pairs from England and Wales. Researchers used twins to better control for factors such as family situation and environment; they focused on 114 twin pairs in which one sibling was bullied while the other was not.

Arsenault said the study showed that bullying can have serious health consequences that should be taken seriously.

The research was published in the February 2008 issue of the Archives of Pediatrics and Adolescent Medicine.