Movement disorders in psychiatric patients.

The observability of movement gives it advantages when trying to draw connections between brain and mind. Disturbed motor function pervades schizophrenia, though it is difficult now to subtract the effects of antipsychotic treatment. There is evidence from patients never exposed to these drugs that dyskinesia and even parkinsonism are to some degree innate to schizophrenia. Tardive dyskinesia and drug-induced parkinsonism are the most common movement disorders encountered in psychiatric practice. While D2 dopamine receptor blockade is a causative factor, both conditions defy straightforward neurochemical explanation. Balanced against the need to manage schizophrenic symptoms, neither prevention nor treatment is easy. Of all disorders classified as psychiatric, catatonia sits closest to organic neurology on the neuropsychiatric spectrum. Not only does it occur in the setting of unequivocally organic cerebral disease, but the alterations of consciousness it produces have 'organic' qualities even when the cause is psychiatric. No longer considered a subtype of schizophrenia, catatonia is defined by syndromic features based on motor phenomenology. Both severe depression and obsessive-compulsive disorder may be associated with 'soft' extrapyramidal signs that resemble parkinsonian bradykinesia. As functional neuroimaging studies suggest, movement and psychiatric disorders involve the same network connections between the basal ganglia and the cerebral cortex.