Modern psychotropic substances such as atypical neuroleptics induce clinically apparent extra-pyramidal motoric symptoms (EPMS) very rarely compared to earlier drugs. An interesting question is whether they cause subclinical EPMS that are unnoticed by the doctor’s eye but have negative influence on the patients’ well-being. Objective methods for the measurement of movements with high spatial and temporal resolution are capable of recognising these subtle motoric changes securely. Experiments that use such a method to examine facial expressions of schizophrenic patients without clinically apparent EPMS during induction of emotion showed that typical neuroleptics such as haloperidol reduce kinematic parameters of facial expression movements significantly, while atypical drugs such as clozapin and olanzapin did not. Further differentiation of these two was achieved by studies of clinically EPMS-free schizophrenic patients using a digital writing table. Patients treated with olanzapin showed a clearly reduced automatization of writing and drawing movements, while those treated with clozapin showed no such change. These first investigations suggest that detailed kinematic analysis of motor function will be of help in classifying psychotropic drugs.
