Neurological soft signs discriminating mood disorders from first episode schizophrenia.

OBJECTIVE

To investigate the specificity of neurological soft signs (NSS) for first episode schizophrenia compared with mood disorders.

METHOD: We assessed NSS in a sample of 60 healthy controls, 191 first episode psychosis patients and 81 mood disorder patients. We used a principle component analysis to identify dimensions of NSS. We subsequently investigated the specificity of these dimensions for schizophrenia and their relationships with medication and symptom scores.

RESULTS

We identified five dimensions; coordination disorders, movement disorders, increased reflexes, dyskinesia and catatonia. These dimensions were related to neural circuits associated with schizophrenia and mood disorders and included the fronto-striatal-thalamic and the fronto-cerebellar pathway. The movement disorder dimension, which was suggestive for the involvement of the fronto-striatal-thalamic pathway, was specific for first episode schizophrenia independent from medication.

CONCLUSION

NSS are the result of circuitry dysfunctions rather than overall dysfunction and a particular set of NSS shows specificity for schizophrenia.