This study aims to investigate the prevalence and distribution characteristics of mental disorders among people aged 18 and above in Shandong Province.

In 2015, an epidemiological survey was carried out to investigate the patterns of mental disorders in 49 counties of Shandong Province. A total of 28 000 individuals aged 18 years or older were selected using the multistage stratified cluster sampling method. All these participants were classified as at a high or low risk of mental disorders according to the assessment results of the revised version of the General Health Questionnaire (GHQ). The diagnosis of mental disorders was confirmed using the Structured Clinical Interview for Diagnostic and Statistical Manual, Forth edition (DSM-Ⅳ) axis I or MMSE. All participants at high risk of mental disorders were evaluated using DSM-Ⅳ or MMSE to confirm the psychiatric diagnoses, while 10% of participants at low risk of mental disorders were randomly selected to be evaluated. The prevalence and its 95% confidence interval of mental disorders were adjusted according to study design and sociodemographic characteristics of the sample. The between-group differences of prevalence were compared using chi-square tests or Fisher′s exact tests as appropriately.

A total of 27 489 individuals completed survey. The adjusted prevalence of any mental disorder was 17.46% (95%CI 17.02%-17.89%). The five most prevalent mental disorder spectrums were substance use disorders (5.29%), mood disorders (4.47%), anxiety disorders (4.46%), intellectual and mental disorders due to physical or substance (1.91%), and psychotic disorders (1.12%). The most common mental disorders were alcohol use disorder (5.27%) and major depressive disorder (2.14%). The prevalence of mental disorders in men was higher than that in women (23.37% vs. 13.89%; χ²=408.91, P<0.01). There was no significant difference in the prevalence of mental disorders between rural residents and urban residents (17.69% vs. 17.20%; χ²=1.05, P=0.305). Of participants with mental disorders, 26.12% (1 047/4 008) had moderate to severe functional impairment and 10.98% (428/3 898) have sought professional help.

The prevalence of mental disorders among people aged 18 and above in Shandong Province is basically consistent with the results of similar domestic studies. The prevalence of mental disorder was higher in men than in women and was not differ in participants living in urban and rural areas. Alcohol use disorder, major depressive disorder, non-specific anxiety disorder and non-specific depressive disorder are most common mental disorders.

Mental disorder; Prevalence; Cross-sectional survey