[Kieron O'Connor's scientific contribution to the characterization and treatment of Tourette's syndrome and obsessive-compulsive disorders].

Background Researcher and psychologist Kieron Philip O'Connor (1950-2019) pioneered the cognitive and behavioural approach at the Institut universitaire en santé mentale de Montréal (IUSMM). It was there that he began a career as a clinical researcher studying Tourette's syndrome (TS) and obsessive-compulsive and related disorder (OCD). At the time, apart from some behavioural approaches, little cognitive intervention was available to treat chronic tics and obsessive-compulsive disorder. Above all, the interventions remained very poorly validated. Objective and questions: Our main aim is to present the cognitive, behavioural and psychophysiological model developed during his successful career and the impact of important research that has marked the field. His research is based on many questions that arose at the beginning of its development in the '90s. Why do many patients not respond to treatments? Why are these patients often misdiagnosed? Are there alternatives to pharmacological treatments? He knew these questions could only be addressed through a multidisciplinary approach combining psychiatry, neurology, clinical psychology and cognitive neuroscience. Thus, he advocated a model incorporating a cognitive, behavioural, and psychophysiological approach based on cutting-edge research evidence. Outline Our chapter presents Dr. O'Connor's journey as a researcher and psychologist at the Institut universitaire en santé mentale de Montréal research center. Thus, we expose the historical context surrounding the treatment of TS and OCD. We will then present the main models that have led to the successful cognitive, behavioural and psychophysiological treatment of chronic tics and the inference-based approach to treat OCD. We will then conclude with multiple orientations, approaches and themes addressed by his team. Method The search was conducted via Medline and PsycInfo with inclusion criteria based on the following criteria: (1) articles published by Kieron O'Connor; (2) written in English or French; (3) original research or journal articles. Results We identified 175 articles grouped into main themes. There are two main conclusions to be drawn. First, psychotherapies conducted according to the CoPs model with adults with TS have shown improvements related to a change in sensorimotor activation patterns that normalize after treatment and allow, among other things, the development of improved motor control. Second, work on OCD has led to the emergence of a new approach that focuses on obsessions as a product of inverse inference. This model has allowed for the development of inference-based approaches, thus allowing work on erroneous doubts, feared self, and inferential confusion. Conclusion The results traced the body of work, in particular his masterpiece, including an inference-based approach for OCD and another on cognitive and psychophysiological management of TS. All of this was intertwined into a model supported by an empirical and phenomenological approach that touched on secondary themes such as body-focused repetitive behaviours, body dysmorphic disorder, eating disorders, hoarding, delusions and certain addictions.