Bullying has long been found to produce lasting effects on its victims, but a new study revealed more evidence on just how pronounced those effects are.

According to a Finnish study published last Wednesday on the journal JAMA Psychiatry, young kids who were often bullied when they were eight years old are more prone to develop mental problems that require treatment when they grow up, Live Science reported.

There have been several studies linking bullying and psychiatric disorders in children, but not much has been said about the lasting effects it has on adults.

According to study author Dr. Andre Sourander of Finland's University of Turku, there are insufficient studies on childhood bullying that also involves long-term follow ups. But Sourander and his team investigated the relationship between bullying at such a young age of eight and how it would affect them as adults by the time they hit 29.

To arrive at their conclusion, researchers gathered data from Finland's register to study more than 5,000 Finnish children. They then asked kids, parents and teachers about bullying. The kids were also followed when they were 16 to 29 years old. 

From the information obtained, the children were then divided into different groups: kids who were not involved in bullying; those who were frequently bullied, but did not bully other kids; those who were bullies themselves; and those who were bullies and victims of bullying at the same time.

The study revealed that 90 percent of the children were not involved in the behavior, but 12 percent were found to have mental health problems before they reach 30 years old.

The study also found that 20 percent of those who were bullies when they were young developed psychiatric issues that required treatment when they grew older. About 23 percent who were bully victims needed treatment before reaching 30.

The children that had the worse mental health effects are those bullies and bullied at the same time when they were kids. These children are the most prone to depression, schizophrenia, substance abuse, and anxiety disorders, as noted in Live Science.

"I think this is an important finding which should be taken seriously," Sourander said, according to FOX News.

Researchers conclude in their study that exposure to bullying, even though kids do not show symptoms of psychiatric disorders, is mostly associated with "severe adulthood psychiatric outcomes."

"Early intervention among those involved in bullying can prevent long-term consequences," the team writes.