Late-onset ADHD: does it exist?

According to current classification systems, attention-deficit/hyperactivity disorder (ADHD) cannot be diagnosed unless its symptoms have been present already in childhood. Recently, this view has begun to be challenged with the thesis that the disorder may have its onset later in life (adolescence or young adulthood). The Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnostic criteria for ADHD are more liberal than those of the International Classification of Disease (ICD). Moreover, reports have begun to emerge demonstrating a different clinical picture in patients diagnosed with ADHD according to current guidelines and in a cohort with the onset in adulthood. The symptomatology of the disease in adults differs from that presented by children. Additionally, theories on the different etiopathogenesis of these entities have been advanced. These data have led to the proposal of distinguishing late-onset ADHD. There are also critical voices in the literature that question the possibility of developing ADHD symptoms in adulthood. Despite insufficient data and arguments to support the thesis of late-onset ADHD, there is a need for discussion and further exploration of the age at which ADHD may appear.