Internet addiction could be making some teenagers depressed and anxious, research suggests.

Scientists investigated links between excessive internet use and mental health problems in more than 1,000 Chinese teenagers with an average age of 15.

They suggest screening children at school to identify at-risk individuals who might benefit from counselling and treatment.

Study participants were asked questions designed to spot signs of anxiety and depression that are known to accompany addiction behaviour. They included the question: “How often do you feel depressed, moody or nervous when you are off-line, which goes away once you are back on-line?”

At the beginning of the study, 62 teenagers – 6.2 per cent of the total – were classified as engaging in “moderately” unhealthy internet use, and two per cent were “severely at risk”.

Nine months later, the teenagers were re-assessed for anxiety and depression. The findings, reported in the journal Archives of Paediatrics and Adolescent Medicine, showed that 8.4 per cent had developed clinical Paediatricsdepression and 0.2 per cent were suffering significant anxiety symptoms.

The authors, led by Lawrence Lam from the School of Medicine in Sydney, Australia, wrote: “This result suggests that young people who are initially free of mental health problems but use the internet pathologically could develop depression as a consequence.”

They added: “Screening for at-risk individuals in the school setting should be considered an effective early prevention strategy.”