[Psychobiology of compulsive disease]

The predominant psychobiological hypotheses regarding the pathophysiology of obsessive-compulsive disorder (OCD) are that a selective basal ganglia dysfunction and a dysregulation of one or several central serotonin (5-HT) subsystem are related to at least some aspects of the syndrome. Recent neuroanatomical, -pharmacological, and -ethological studies indicate a complex perceptual and cognitive role for the basal ganglia, particularly the striatum and the pallidum, in addition to the well-established motor functions. Obsessive-compulsive symptoms in syndromes with extrapyramidal-motor dysfunction, such as Gilles de la Tourette syndrome or Chorea minor (Sydenham), response to specific pharmacotherapy, behavioural therapy, and psychosurgery, as well as findings derived from brain imaging studies including positron emission tomography (PET) support the view of a frontal cortex/basal ganglia dysfunction in OCD. In addition, growing evidence suggests that potent inhibitors of 5-HT reuptake and other 5-HT subsystem-selective agents, such as the azapirones with partial agonist properties at the 5-HT1A receptor, are effective in OCD not only has improved the therapeutic perspective but may also reveal clues to the aetiopathogenesis of OCD. Much of this evidence has resulted from the discovery of multiple receptors and signal transduction pathways for 5-HT and from experiments relating the action of 5-HT receptor-selective agents to discrete effects in different subsystems. Among these 5-HT subsystems the 5-HT1D and 5-HT1A receptor-effector system complex appears to play a central role in the pathophysiology of OCD symptoms and the mechanism of action of antiobsessional drugs. Recent psychoneurobiological findings are reviewed briefly and evaluated in the context of the 5-HT and basal ganglia hypothesis of OCD.