Two out of three people who were treated for these problems were in their teens to 30s, while the number of patients in their 20s has grown steadily over the last five years.

Twice as many men as women suffer from those disorders.

According to the Health Insurance Review and Assessment Service last week, 13,000 to 14,000 people a year were diagnosed with personality or behavioral disorders between 2010 and 2014.

Young men are more likely to suffer personality or behavioral disorders that make them prone to sudden outbursts of rage and problems forming and maintaining relationships.

In 2014, men in their 20s accounted for 28 percent of patients, men in their 30s for 18.4 percent and teenage boys for 17.3 percent.

Personality disorder is a catch-all term for problems such as excessive distrust, indifference and aggression. Sufferers often have persistent problems with relationships and are likely to fall foul of the law. They are prone to compulsive behavior such as pathological gambling, arson and kleptomania, and have problems with anger management.

Kim Hyun-soo at Myongji Hospital said, "Children need to learn socially appropriate ways to deal with their impulses or conflicts either at home or at school, and when they fail to do so due to over-protective parents, video game addiction or isolation, they often display these disorders later on."

"Men are treated more often than women because they tend to be more aggressive and violent, but many women also suffer from this problem," Kim added.

Every year an estimated 50,000 people are arrested for assault due to compulsive behavior, while another 50,000 inflict injury, according to police data from 2011 to 2013.

Woo Jong-min at Paik Hospital said, "Korean society is prone to conflicts, and there is a lack of civic awareness or social mechanisms to filter out such factors, raising the chances of personality or behavioral disorders to develop into outbursts of rage. If minor disputes or fits of anger become habitual, they tend to become more intense and require treatment."

Woo added that it is important for people who know individuals with such diso rders to recommend treatment, since it is difficult for them to seek help voluntarily.

Shin Eui-jin, a lawmaker with the ruling Saenuri Party and child psychologist, said, "Personality or behavioral disorders can become difficult to treat unless they are dealt with in childhood. We need to get schools to bolster programs to deal with this issue."