Comorbidity of obsessive-compulsive disorder / Ruth Gross-Isseroff and Abraham Weizman -- Obsessive-compulsive disorder and major depression: associated and different / Richard B. Rosse [and others] -- Obsessive-compulsive disorder : comorbidity with obsessive-compulsive spectrum disorders / Christine Lochner and Dan J. Stein -- Schizo-obsessive disorder / Michael Poyurovsky, Abraham Weizman and Ronit Weizman -- Obsessive-compulsive disorder and attention deficit disorder: a challenging comorbidity / Tamar Steinberg and Alan Apter -- Autism spectrum disorders, autistic traits and personality disorders in obsessive-compulsive disorder / Susanne Bejerot -- Neurological disorders of the basal ganglia and obsessive-compulsive disorder / Roberto Cavallaro, Cristina Cavallini and Laura Bellodi -- Antipsychotics in OCD / Joseph Zohar [and others] -- State of the art and future directions in the pathophysiology of obsessive-compusive disorder / Donatella Marazziti, Francesco Mungai and Bernardo Dell'Osso.