Time Trends in the Frequencies of ADHD and Stimulant Medication

Time-trends in the frequencies of mental disorders represent specific challenges for the planning of services. The present review addresses the specific question whether or not there are time changes in terms of an increase of prevalence and incidence rates of attentiondeficit hyperactivity disorders (ADHD) based on findings from international epidemiological studies from several decades. While there is no evidence that prevalence rates of ADHD have systematically increased, various national and international incidence studies on ADHD but also prevalence and incidence studies on prescribed medication indicate that the number of treated people with ADHD has increased significantly in the recent past. This increase remains even after adjusting for the general increase in the number of persons admitted to psychiatry for any disorder. Thus, the gap between those in need of treatment and those who actually receive treatment for ADHD has narrowed over time. However, after years of an increase, in recent years German studies dealing with prescriptions of medications have shown also a declining trend.