[ADHD during childhood and subsequent psychotic disorder: A link?]

Abstract

Objectives: Attention Deficit with/without Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder with frequent comorbid psychiatric disorders. Several studies have underlined the increased risk of developing a psychotic disorder subsequent to a childhood ADHD. The aim of our review is not only to clarify this association and the related physiopathology but also to understand the consequences for therapeutic management.

Methods: We processed a narrative review of available literature based on a research of the PubMed database. Articles related to ADHD and psychotic disorder on a genetical, clinical or biological level were selected by one of the authors.

Results: ADHD and psychotic disorders share neonatal, environmental, and genetic risk factors. On a neurobiological level, both disorders are concerned by a dysfunction of the dopaminergic system with an abnormal regulation of dopaminergic neurons' phasic and tonic activity. Our review aims to explain the « dynamic » model of dopaminergic dysfunctions and propose some guidance for pharmacological treatment of ADHD, with or without psychotic disorder. This model offers a better understanding of why methylphenidate is not associated to an increased risk of psychotic disorder and could act as a protective factor. Association between ADHD and psychotic disorders could be explained by some comorbidities such as substance use disorders which are frequently associated with both conditions and could act as mediator in the genesis of psychotic disorders following ADHD during childhood. Our review also focuses on an epidemiological bias that could be found in some studies such as possible diagnostic errors, as some non-specific clinical signs could be found in both late diagnosed ADHD and in "at risk mental state" of psychosis.

Conclusion: ADHD and psychotic disorders share common risk factors, neurobiological pathways and clinical symptoms. Perspectives for future studies are proposed considering a dimensional aspect of psychiatric disorders using, for example, Research Domain Criteria and exploring the link between the two conditions.

Keywords: ADHD; ARMS; Methylphenidate; Psychosis; Schizophrenia; Schizophrénie; TDAH; Trouble psychotique.