Tourette's and Comorbid syndromes: Obsessive compulsive and attention deficit hyperactivity disorder. A common etiology?

Tourette's syndrome (TS), a neuropsychiatric movement disorder that manifes ts itself in childhood, is often associated with comorbid symptomatology, s uch as obsessions, compulsions, hyperactivity, distractibility, and impulsi vity. Epidemiological studies suggest that a substantial number of TS patie nts develop clinical Ipc,els of obsessive-compulsive disorder (OCD) and/or attention deficit hyperactivity disorder (ADHD). This review aims to provid e an integrated account of the three disorders in terms of their comorbidit y. Neuroimaging studies suggest that all three disorders involve neuropatho logy of the basal-ganglia thalamocortical (BGTC) pathways: TS in the sensor imotor and limbic BGTC circuits; OCD in the prefrontal and limbic BGTC path ways; and ADHD in the sensorimotor orbitofrontal, and limbic BGTC circuits. The pattern of comorbidity and other evidence indicates that the TS gene(s ) may be responsible for a spectrum of disorders, including OCD and ADHD bu t also that the disorders OCD and ADHD can exist in their own right with th eir owl etiologies. (C) 1999 Elsevier Science Ltd.