ADHD & Comorbidity: Diagnostic Challenges in Adults

Plain-language summary

Research suggests that diagnosing ADHD in adults can be tricky, especially when other mental health conditions are present. This is because symptoms can overlap, making it hard to tell what belongs to which condition. While there are challenges, healthcare professionals are working to improve diagnosis and treatment.

Key findings

• One major challenge is the need for patients to recall if their ADHD symptoms started in childhood, which can be difficult after many years.
• When ADHD and substance use disorders occur together, it can be hard for doctors to tell them apart because some symptoms are very similar.
• It is common for adults with ADHD to also have other conditions like personality disorders or bulimia nervosa, adding layers of complexity to diagnosis.
• Some research highlights that ADHD is found in a significant percentage of people with substance use disorders, showing how frequently these conditions co-occur.
• The lack of specialized adult ADHD clinics in some areas means that general psychiatric services are often responsible for diagnosis and management, which can impact the standard of care.

Studies cited (6)

1. Prevalence and moderators of personality disorders in adults with ADHD: A meta-analysis — Adamis D, Zhang T, Gavin B (2026, Psychiatry research, meta-analysis)

   DOI: 10.1016/j.psychres.2026.117085

2. Diagnosis and treatment of patients with comorbid substance use disorder and adult attention-deficit and hyperactivity disorder: a review of recent publications. — Duco van der Burg, C. Crunelle, F. Matthys (2019, Current Opinion in Psychiatry, review)

   PURPOSE OF REVIEW Attention-deficit and hyperactivity disorder (ADHD) often presents with comorbid substance use disorders (SUD). Due to similarities in key symptoms of both disorders and suboptimal efficacy of the available treatments, clinicians are faced with difficulties in the diagnosis and treatment of these patients with both disorders. This review addresses recent publications between 2017 and 2019 on the etiology, prevalence, diagnosis and treatment of co-occurring ADHD and SUD. RECENT FINDINGS ADHD is diagnosed in 15-20% of SUD patients, mostly as ADHD with combined (hyperactive/in

3. The difficulties of Adult ADHD management within a Community Mental Health Team — S. Haugh, H. Belay (2024, European psychiatry, review)

   Introduction ADHD is a neurodevelopmental disorder characterised by: inattention, hyperactivity and impulsivity.Diagnosis of ADHD in adults is complex, owing to the need for retrospective evidence that symptoms began in childhood as well as the high rates of comorbid mental health conditions. There are no public specialized clinics for adults with ADHD in Ireland. In their absence, referrals are sent to general adult psychiatry. Objectives An audit of standards of care received by patients with ADHD against those set by the NICE guidelines. Methods Care received pre and 8 weeks post MDT (multi

4. Bulimia nervosa patient diagnosed with previously unsuspected ADHD in adulthood: clinical case report, literature review, and diagnostic challenges — Ioannidis K, Serfontein J, Müller U (2014, The International journal of eating disorders, review)

   DOI: 10.1002/eat.22231

5. Sociodemographics, Comorbidities, Healthcare Utilization and Work Productivity in Japanese Patients with Adult ADHD — E. Kirino, Hideyuki Imagawa, T. Goto (2015, PLoS ONE, other)

   Objectives This study compared the sociodemographic characteristics, comorbidities, healthcare resource utilization, and work productivity among Japanese adults who reported being diagnosed with attention-deficit/hyperactivity disorder (ADHD) to those of a non-ADHD control population. Methods Data for this study were captured from an online survey of adults in Japan conducted by Kantar Health using consumer panels. A total of 84 survey participants reported they had received a diagnosis of ADHD from a physician. Survey responses pertaining to functional status and resource utilization from thi

6. ADHD in Adulthood: Clinical Presentation, Comorbidities, and Treatment Perspectives — Bogdańska-Chomczyk E, Majewski MK, Kozłowska A (2025, International journal of molecular sciences, other)

   DOI: 10.3390/ijms262211020 PMCID: PMC12652008