Comorbid ADHD and schizophrenia and the use of psychostimulants: a scoping review protocol

Introduction Schizophrenia and attention deficit hyperactivity disorder (ADHD) are psychiatric disorders that have a profound impact on patients and healthcare systems globally. There is preliminary evidence suggesting a potential association between the two in terms of symptomatology and genetic underpinning. There is a paucity of guidance regarding pharmacological approaches for patients with comorbid ADHD and schizophrenia. There is a concern that psychostimulants may be more harmful than therapeutic. This scoping review protocol aims to systematically review the evidence for potential harm and benefit of psychostimulants among patients with comorbid ADHD and schizophrenia and identify research gaps.Methods and analysis This scoping review will employ a systematic and iterative approach to identify and synthesise the literature on the topic of psychostimulant use among patients with comorbid schizophrenia and ADHD, based on Arksey and O'Malley's framework. A search will be conducted in relevant databases, including MEDLINE (Ovid), Embase (Ovid), PsycINFO and ISI Web of Science. Additionally, grey literature will be sought. The scoping review will involve two independent reviewers screening the search results. The initial screen will be of title and abstract, and the subsequent full-text review will determine eligibility. A descriptive overview of the eligible studies will be provided. This scoping review has been registered at https://osf.io/cmn5s.Ethics and dissemination There is a paucity of high-quality evidence available to clinicians when making decisions regarding the prescription of psychostimulants to patients with comorbid schizophrenia and ADHD. To the best of our knowledge, this will be the first scoping review to examine the evidence addressing this clinical scenario. This review, therefore, has the potential to contribute to decision-making processes for this patient group, thereby improving patient outcomes. Furthermore, as this review is designed to identify research gaps, we aim to contribute to the development of a research agenda that will benefit patients, clinicians and healthcare systems. The dissemination strategy will involve open access peer review publication and scientific presentations.