Attention-deficit/hyperactivity disorder (ADHD) was initially considered as a childhood psychiatric disorder. However, longitudinal observations have revealed that ADHD symptoms may persist in adulthood among approximately 50% of the patients . Adult ADHD is associated with impaired social outcome and frequent comorbidities such as mood disorders, personality disorders, and substance use disorders [2,3]. Correctly identifying and treating ADHD can significantly improve the global functioning and cognition of adult subjects, and reduce the intensity and frequency of the comorbid states [2,3]. Nonetheless, the clinical features of adult ADHD are clearly different from the youth form [1,2], and ADHD symptoms are easily mixed up in adults with symptoms of the comorbid conditions [2,3]. These clinical intricacies can make the diagnosis of ADHD difficult in adults. Moreover, the management of methylphenidate in adult subjects is also associated with specific risks and pitfalls, such as abuse and tampering behaviors, and additional safety risks . Put together, it appears crucial to identify and treat ADHD in adults, but the clinical and therapeutic complexities of adult ADHD require improved expertise and caution from adult psychiatrists and addiction specialists. In this thematic session of the 2015 French Psychiatry Congress, three French leading experts of adult ADHD will address the aforementioned clinical and therapeutic issues of the adulthood form of this disorder. David Da Fonseca, professor of child psychiatry in Marseille, will disentangle the clinical features of adult ADHD from the typical symptoms observed in the youth form. Mélina FATSEAS, associate professor of psychiatry and addiction medicine in Bordeaux, will specifically focus on the many and complex relationships observed between adult ADHD and substance use disorders. Last, Nicolas Simon, professor of addiction medicine and psychopharmacology in Marseille, will synthesize what are the very risks and issues with prescribing methylphenidate in adults.