Mental disorders in drug users have received increasing attention. However, there are no any epidemiologic data available in regard to substance use disorders (SUD) and other mental disorders in drug users in Yunnan, one region that is hit hardest by epidemic of drug use in China.

To investigate the co-prevalence of SUD and a common mental disorder, axisⅠdisorders, among Yunnan's drug users.

A cross-sectional survey was conducted among a convenient sample of 598 male drug users who received detoxification treatment from the 5th Compulsory Detention and Forced Detoxification Center of Yunnan Province and Dali Compulsory Detention and Forced Detoxification Center between August and November, 2020. According to the diagnosis of SUD, the participants were divided into three groups: opioid use disorder group (n=245) , methamphetamine use disorder group (n=197) and double use disorder group (n=146) . The Chinese version of SCID-Ⅰ/P was used to assess the prevalence of common axisⅠmental disorders (psychosis disorder, affective disorder, alcohol use disorder, and sedative-hypnotic use disorder) . The lifetime prevalence of these disorders among the three groups was compared.

Among the 598 cases, there were 588 cases diagnosed with SUD (opioid, methamphetamine, or both) . The lifetime prevalence of psychosis disorder, alcohol use disorder, sedative and hypnotic use disorder among the three groups was significantly different (P < 0.05) . The overall lifetime prevalence of schizophrenia, other primary and drug induced psychotic disorders was 15.82%. The lifetime prevalence of psychotic disorder in opioid use disorder group (5.31%) was lower than that of methamphetamine use disorder group (20.30%) or that of double use disorder group (27.40%) (P<0.05) . The overall lifetime prevalence of affective disorders was 21.77%. To be specific, the lifetime prevalence of affective disorders was 17.14% in opioid use disorder group, 25.38% in methamphetamine use disorder group, and 24.66% in double use disorder group. The overall lifetime prevalence of alcohol use disorder was 42.18%. Specifically, opioid use disorder group had lower lifetime prevalence of alcohol use disorder than methamphetamine use disorder group (35.10% vs 45.69%) and than double use disorder group (35.10% vs 49.32%) (P<0.05) . The overall lifetime prevalence of sedative or hypnotic use disorder was 13.61%. The lifetime prevalence of sedative or hypnotic use disorder was 19.18%, 22.60% and 0 in opioid use disorder group, double use disorder group, and methamphetamine use disorder group, respectively.

The prevalence of the above-mentioned mental disorders in drug users in Yunnan Province was much higher than that in the general population. Moreover, these mental disorders may be even more prevalent in methamphetamine use disorder population than in opioid use disorder population.