Movement disorders in patients with schizophrenia and in their siblings: symptoms, side effects and mechanical measurements

This thesis focuses on several aspects of movement disorders in patients with schizophrenia and in their unaffected siblings. The main hypothesis is that movement disorders are not just side effects of antipsychotic medication but may also be symptoms of the illness itself and are related to the (genetic) risk of developing the disease. To address these questions a systematic literature search was followed by a clinical prevalence and association study of movement disorders with schizotypy in siblings of patients with schizophrenia, and a candidate gene study of movement disorders in patients using antipsychotic medication. Further, we developped a mechanical instrument and examined whether mechanical measurement of lingual force variability reflects tardive tongue dyskinesia and whether mechanical measurement of movement disorders in siblings of patients with schizophrenia is more sensitive than clinical rating scales. The results of this thesis suggest that movement disorders are associated to antipsychotic naïve patients with schizophrenia and are also more prevalent in their unaffected siblings compared to controls. This could imply that movement disorders represent symptoms of schizophrenia and may be markers of vulnerability of developing the disease.In addition the results of this thesis indicate that in siblings of patients with schizophrenia, mechanical instruments may also be more sensitive for detecting subclinical movement disorders than traditional clinician-based rating scales.