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.

The specificity of neurological signs in schizophrenia: a review.

This review examines the extent to which neurological signs are more prevalent in schizophrenia patients, compared to mood-disorder patients and healthy subjects, and whether there is a pattern in any of the differences that may be found. We included 17 studies and calculated the weighted mean prevalence of 30 neurological signs. The prevalence of most signs appears to be significantly different between schizophrenia patients and normal controls, but there are fewer differences between schizophrenia and mood-disorder patients. Several signs - poor stereognosis and rhythm tapping - are even more prevalent in mood-disorder patients than in schizophrenia patients. Only lack of extinction, dysdiadochokinesia, poor tandem walk, finger-thumb-opposition and articulation are significantly more prevalent in schizophrenia compared to mood-disorder patients. Impaired motor coordination seems most specific to schizophrenia. The discriminating power of motor sequencing still needs to be studied. So far, there is no evidence of a clearly interpretable pattern of neurological signs distinguishing schizophrenia patients from mood-disorder patients.

Psychopathology and cognition in schizophrenia spectrum disorders: the role of depressive symptoms.

The cognitive correlates of five symptom dimensions based on PANSS ratings were examined in a group of 50 recent onset psychotic patients, using both objective and subjective cognitive measures. We were particularly interested in the depression dimension, since it has not been studied extensively thus far. The depression dimension showed a high number of correlations with both objective and subjective cognitive measures, such as problems with simple and divided attention, psychomotor slowing and subjectively experienced distractibility, overload and diminished attentional control. The other dimensions, including negative symptoms, have less cognitive correlates. It is possible that previous studies based on a three-dimensional model confounded correlates of negative symptoms with correlates of depressive symptoms. The results of this study suggest the need for more research into the mechanisms underlying the relationship between depressive symptoms and cognitive functioning in schizophrenia, and that patients with depressive symptoms are less efficient in information processing, but can compensate by investing more mental effort. Because subjective cognitive measures were related to mental effort in previous research, they can be a useful tool in future research.