Depression, anxiety disorders, bipolar disorder, SUDs, and personality disorders are the most prevalent mental comorbidities that co-occur with ADHD in adults. Figure 1 summarizes the overlapping and distinguishing characteristics of various illnesses.
ADHD (attention deficit hyperactivity disorder) is a psychiatric illness that has a significant personal and societal impact. While ADHD is well-known in the juvenile community, where it was initially defined as a clinical diagnosis in the 1930s, attention has switched to adult ADHD detection and management. Adult ADHD frequently presents with a more diverse clinical presentation that extends beyond the basic motor symptoms seen in children and encompasses a broader range of emotional dysregulation and functional impairment.
Our understanding of adult ADHD is evolving as our diagnostic systems move toward a more dimensional approach to mental disorder classification. Practicing clinicians are now aware of the heredity of ADHD as well as the vast range of clinical presentations of adult ADHD. Up to 80% of individuals with ADHD have at least one mental disease, such as mood and anxiety disorders, substance use disorders (SUD), or personality problems. This can make it difficult to notice and diagnose ADHD in adults, and despite ongoing professional debate, the majority of data suggests that ADHD is under-diagnosed and under-treated in adults. Despite the difficulties in diagnosing ADHD in adults with complicated clinical presentations, there are effective treatments that have been shown to improve clinical and functional outcomes, including important aspects of psychosocial functioning like social relationships, workplace performance, and parenting skills. As a result, physicians are ecstatic when they recognize and successfully manage ADHD in adults. It has been claimed that preventing the onset of mental comorbidities such as mood and anxiety disorders, or SUDs, through early and optimum treatment of ADHD could potentially alter the trajectory of psychiatric morbidity down the road.
Thus, the objectives of this article are to review the available evidence on the prevalence, burden, and neurobiology of adult ADHD, to describe how a practical, dimensional approach can assist clinicians in identifying ADHD in patients with complex presentations, and to inform appropriate management decisions in order to improve patient outcomes in this under-treated population. This article answers some common clinical questions based on available evidence as well as our collective experience in the management of adult ADHD and comorbidities, with the recognition that the evidence base continues to evolve and that there is a lack of quality evidence to guide the management of complex patient presentations.