Animal models of attention-deficit/hyperactivity disorder: Diversity and validity

Attention-deficit/hyperactivity disorder (ADHD) is one of the most widespread neurodevelopmental disorders globally, marked by chronic symptoms of inattention and/or hyperactivity-impulsivity. Its multifactorial origin and phenotypic heterogeneity make it a complex condition, and despite substantial research, the precise causes of ADHD remain poorly understood. A significant challenge in advancing ADHD research is the lack of a unified resource that consolidates animal models across different species and considers the diversity of ADHD subtypes and associated coexisting conditions. This lack of standardization of the models delays progress in developing a deeper understanding of the neuronal and molecular mechanisms behind the disorder, which is essential to advance its treatment. This review aims to bridge this gap by offering a comprehensive compilation of available animal models used in ADHD research, accompanied by an evaluation of their validity. It is essential for researchers to have access to a range of models, each selected based on the specific scientific objectives and hypotheses of their studies. The review highlights that an extensive approach to studying ADHD, including its various dimensions and associated conditions, requires the use of multiple animal models. Moreover, it emphasizes the importance of assessing the mechanisms and broader effects of current pharmacological treatments while also exploring novel therapeutic possibilities. By providing a clearer and more structured resource, this work pursues to assist researchers in selecting the most appropriate models for their investigations. Additionally, it aims to contribute to the broader understanding of ADHD neurobiology, offering new perspectives for new models and the potential for more targeted therapeutic strategies. SIGNIFICANT STATEMENT: Attention-deficit/hyperactivity disorder (ADHD), one of the most prevalent neurodevelopmental disorders globally, is marked by inattention and/or hyperactivity-impulsivity. This review evaluates animal models for ADHD and its coexisting conditions, emphasizing the need for diverse models to reflect its complexity. It underscores the importance of selecting appropriate models to address specific research goals and investigates current and potential pharmacological treatments, providing a vital resource for advancing ADHD research and improving therapeutic approaches.