Advances in the neurochemistry and neuropharmacology of Tourette syndrome

Tourette syndrome (TS) is the primary tic disorder that reaches most commonly medical attention and monitoring, with an estimated prevalence close to 1% between 5 and 18 years of age. Motor and phonic tics are the core features of TS. In addition to their well-characterized phenomenology, tics display a peculiar variability over time, which is strongly influenced by a variety of contextual factors. The sensory phenomena of TS are increasingly recognized as another crucial symptom of TS and consist of premonitory urges and somatic hypersensitivity. A relevant proportion of patients with TS display complex, tic-like, repetitive behaviors that include echophenomena, coprophenomena, and nonobscene socially inappropriate behaviors (NOSIBs). The burden of behavioral comorbidities is very important in determining the degree of disability of TS patients. Only a small minority of TS patients presents exclusively with a tic disorder. Obsessive-compulsive symptoms and related disorder (OCD) are common in TS, and the clinical distinction between compulsions and complex tics may be difficult in some cases. Probably, the presence of comorbid attention deficit hyperactivity disorder (ADHD) is the main determinant of cognitive dysfunction in TS patients and influences heavily also the risk of developing disruptive behaviors. Affective disorders, impulse control disorders, autism spectrum disorders, and personality disorders complete the wide psychopathological spectrum of this condition, but have been less investigated than OCD and ADHD. The complexity of the Tourette spectrum has been confirmed by cluster and factor analytical approaches, and is likely to inform the study of the genetic basis of this disorder, as well as future reappraisal of its nosography, with the development of novel clinical subtypes. © 2013 Elsevier Inc.