¹Takeda UK Ltd, Medical Affairs, London, United Kingdom, ²Hospital Universitari Vall d'Hebron, Department of Mental Health, Barcelona, Spain, ³Vall Hebron Research Institute, Department of Psychiatry and Forensic Medicine, Barcelona, Spain, ⁴Cumbria, Northumberland, Tyne and Wear NHS Foundation Trust, Adult ADHD Services, Newcastle upon Tyne, United Kingdom, ⁵Uppsala University, Department for Women’s and Children’s Health, Uppsala, Sweden, ⁶Takeda Pharmaceuticals International AG, Global Medical Affairs, Zurich, Switzerland, ⁷QVIA, Statistics, Barcelona, Spain, ⁸University Hospital Frankfurt - Goethe University, Department of Psychiatry, Psychosomatic Medicine and Psychotherapy, Frankfurt am Main, Germany

Background: The prevalence of attention deficit hyperactivity disorder (ADHD) in patients with psychiatric disorders has been estimated as 6.9%–38.8%. However, it is likely that ADHD is underdiagnosed in this patient population as symptoms often overlap with or are masked by other psychiatric disorders. Delayed diagnosis or untreated ADHD can exacerbate psychiatric comorbidities, contribute to a poor treatment response, impact quality of life (QoL), and increase healthcare costs. Understanding the prevalence of ADHD in patients with psychiatric disorders may increase recognition and improve diagnosis allowing patients to receive appropriate clinical management and timely treatment.

Aims & Objectives: The LANDSCAPE study (NCT04943796) aimed to estimate the prevalence of ADHD and adverse health outcomes in adult patients with psychiatric disorders.

Method: LANDSCAPE was a non-interventional, observational, two-part study in adult outpatients with ≥1psychiatric disorder for ≥12 months. Part I was a cross-sectional study of patients with major depressive disorder, anxiety disorder, bipolar disorder, substance use disorders, borderline personality disorder, and/or binge eating disorder who were consecutively assessed for ADHD. Information was collected from the patient’s medical chart. The primary outcome measure was an estimate of the prevalence of ADHD (DSM-5criteria) assessed via the DIVA-5 and ASRS. Secondary measures included the sociodemographic and clinical characteristics of the study population, indicators to perform a complete diagnosis assessment for ADHD, psychological/psychiatric clinical management in the previous 12 months, functionality level, and QoL.

Results: A total of 228 patients with a mean (SD) age of 37.5 (12.1) years were assessed from Canada, Germany, Spain, Sweden, Switzerland, and the UK; 168 (73.7%) received a diagnosis of ADHD vs 60(26.3%) who did not. Among the patients with ADHD, 95/162 (58.6%) had moderate ADHD and 107/165(64.8%) had a combined ADHD presentation. Sociodemographic characteristics did not significantly differ between patients with and without ADHD. However, patients with ADHD were more likely to: exercise less frequently (p<0.0001); have a family history of ADHD (65 [38.7%] vs 7 [11.7%]; p=0.0003); have previously attempted suicide (45 [26.8%] vs 10 [16.7%]; p=0.0217) than those without ADHD. Among patients with ADHD, the most common comorbidities were major depressive disorder (59.5%), anxiety disorder (44.6%), and substance use disorder (20.8%). The number of psychiatric diagnoses/patient (1, 2,3+) were similar between those with and without ADHD. Triggers prompting an ADHD diagnostic assessment that were more frequently observed in patients with ADHD were problems with organization, household routines, self-regulation, unresponsiveness to treatment, addiction, low self-esteem, anger issues, family history, financial difficulties and patient’s own wish. No differences were found in clinical management or treatment between the two groups. Finally, adult patients with ADHD showed a significantly higher mean Functional Assessment Short Test score, indicating greater functional impairment (p=0.0002), and a lower QoL total score (p=0.0141) compared with those without ADHD.

Discussion & Conclusions: These findings emphasise the importance of considering ADHD in patients with complex psychiatric presentations and underscore the substantial burden faced by adult patients with ADHD, characterised by significant functional impairment, reduced quality of life, and a high prevalence of comorbidities.