Although promotion of good mental health, prevention and early intervention can be implemented over the lifespan, the benefits are maximal when young people are targeted at around the time of onset of mental disorders. Unfortunately, the peak ages and ranges at onset for mental disorders are not fully established, with conflicting findings across [27, 28] and within studies [29], partly due to methodological limitations, including selection biases in recruitment for clinical studies [30]. General population-level studies (birth cohort, cross-sectional or incidence studies) provide the most robust onset age estimates [30]. However, to date, no comprehensive epidemiologically sound, large-scale meta-analysis has pooled data from these population-based studies that are representative of the general population to estimate the peak age at the onset across the globe and the proportion of individuals with mental disorders at specific age points. This study’s goal was to fill this gap aiming to optimise timely intervention, prevention and promotion of good mental health opportunities at the time of onset of mental disorders.
