Young’s Internet addiction Test (IAT), Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), Self-Rating Anxiety Scale (SAS), Self-Rating Depression Scale (SDS), Barratt Impulse Scale (BIS-11) and Pittsburgh Sleep Quality Index (PSQI) were used to observe the severity of Internet addiction, mental status, sleep quality and impulsive trait of all patients at baseline and 40th days of treatment; and MAOA mRNA data were collected at baseline and 40th days of treatment. Here, MAOA is linked to major depressive disorder.