Question: Is manualized cognitive behavioral therapy–based indicated prevention effective in reducing symptoms of gaming disorder and unspecified internet use disorder and rates of these disorders in at-risk high school students?

Findings: In this cluster randomized clinical trial of 422 at-risk adolescents with gaming disorder and unspecified internet use disorder, the PROTECT (Professioneller Umgang mit technischen Medien [Professional Use of Technical Media]) intervention group had a significantly greater reduction in symptoms over 12 months compared with the assessment-only control group (39.8% vs 27.7%). Differences in incidence rates did not reach significance.

Meaning: Findings of this trial indicate that the PROTECT intervention in high schools is effective in reducing symptoms of gaming disorder and unspecified internet use disorder.