The mean age and gender distribution of patients seeking help for mental disorders have not yet been investigated systematically. Epidemiological surveys can provide data on gender distribution of disorders and an age range in which a disorder is most frequent, but do not offer data on the average help-seeking patient, and they are usually conducted by lay interviewers with non-clinical subjects. However, this information on age and gender can be simply extracted from randomized clinical trials (RCTs) in which consecutive clinical patients are included. As it can be assumed that the average patient tends to participate in a clinical trial when her/his illness severity has reached its highpoint, the mean age of patients in RCTs is a good estimator of the peak severity of a disorder. In RCTs, diagnoses are made by psychiatrists and only clinical patients fulfilling a minimum degree of severity are included. From 10.465 records found by electronic and hand search, we extracted 832 eligible RCTs with 151,336 patients with the 19 most relevant mental disorders. We provide a table with the mean age, standard deviation and gender distributions of all major mental disorders. These results can be used in scientific articles and educational materials and can help health care providers or researchers planning treatment programs. Patients can be informed about the natural course of the disorder. By determining the reasons why some disorders occur predominantly in a certain age or have an unbalanced gender distribution information the aetiology of these disorders may further be elucidated.
Keywords: Gender; Mean age; Mental disorders; Randomized controlled studies.