Background: Early onset of mental disorders is a major social and public health concern as it affects individuals in their most formative years. The impact is more pronounced when early onset is also associated with treatment delay. Little is known about the age of onset (AOO) for mental disorders and its predictors in Singapore.
Method: A national mental health survey was conducted among adult residents aged 18 years and above in Singapore. The composite international diagnostic interview (CIDI 3.0) was used to establish the life-time diagnosis of major depressive disorder (MDD), dysthymia, bipolar disorder, generalized anxiety disorder (GAD), obsessive compulsive disorder (OCD) and alcohol abuse and dependence, and the age of onset as well as any subsequent treatment contact.
Results: A total of 6,616 respondents (mean age of 43.9 years) participated in the survey giving a response rate of 75.9 %. The median AOO for having any one of the mental disorders was 22 years with variation among the different disorders. Predictors for AOO varied across the mental disorders. Only 8 % had sought any treatment in the first year after onset. Males, those belonging to Malay and Indian ethnicities and 50+ age cohorts were less likely to have made treatment contact in the year of onset.
Conclusion: Nearly half of the respondents with any life-time mental disorder would have its onset by age of 22 years, and very few had sought treatment within the first year from onset. The study also identified socio-demographic predictors associated with AOO for mental disorders and delayed treatment contact, thus highlighting a vulnerable subpopulation that can be targeted for outreach and early interventions.