AMES, Iowa, Jan. 18 (UPI) — A study of children in Singapore found those who play 20 hours of video games a week are more likely than others to be anxious or depressed, researchers say.

However, the study published online ahead of print in February’s Pediatrics, says spending many hours with a PlayStation or an Xbox daily can lead to serious psychiatric problems in children, and “pathological” video game playing may not be just a result of pre-existing mental disorders, MedPage Today reported.

Douglas Gentile of Iowa State University in Ames, Iowa, and colleagues say depression, social difficulties and poor school performance seemed to act as outcomes of pathological gaming.

Video game-playing habits were considered pathological when children considered themselves to have at least five or 10 behaviors listed on a questionnaire, such as the hours spent playing video games, whether schoolwork suffered or whether they ever stole money to buy games, Gentile says.

The researchers also find that after the two-year study of 3,000 children, the more pathological gaming symptoms participants had at baseline, the more likely they were at the last follow-up to show symptoms of depression, anxiety, social phobia and lower school grades.

The researchers say they do not see why the findings may not apply to other countries.