No abstract

The translation from psychiatric core symptoms to brain functions and vice versa is a largely unresolved issue. In particular, the search for disorders of single brain regions explaining classical symptoms has not yielded the expected results. Based on the assumption that the psychopathology of psychosis is related to a functional imbalance of higher-order brain systems, the authors focused on three specific candidate brain circuitries, namely the language, and limbic and motor systems. These domains are of particular interest for understanding the disastrous communication breakdown during psychotic disorders. Core symptoms of psychosis were mapped on these domains by shaping their definitions in order to match the related brain functions. The resulting psychopathological assessment scale was tested for interrater reliability and internal consistency in a group of 168 psychotic patients. The items of the scale were reliable and a principal component analysis (PCA) was best explained by a solution resembling the three candidate systems. Based on the results, the scale was optimized as an instrument to identify patient subgroups characterized by a prevailing dysfunction of one or more of these systems. In conclusion, the scale is apt to distinguish symptom domains related to the activity of defined brain systems. PCA showed a certain degree of independence of the system-specific symptom clusters within the patient group, indicating relative subgroups of psychosis. The scale is understood as a research instrument to investigate psychoses based on a system-oriented approach. Possible immediate advantages in the clinical application of the understanding of psychoses related to system-specific symptom domains are also discussed.

Background: Motor symptoms are frequent in schizophrenia and relevant to the diagnosis of subtypes. However, the assessment has been limited to observations recorded in scales and experimental designs. The aim of this study was to use wrist actigraphy to obtain motor activity data in 3 schizophrenia subtypes. Methods: In total, 60 patients with schizophrenia (35 paranoid, 12 catatonic, 13 disorganized) were investigated using continuous wrist actigraphy over 24 h in an inpatient setting on average 38 days after admission. Data of the wakeful hours of the day were analyzed. Results: The activity level was predicted by schizophrenia subtype and by the type of antipsychotic medication. The movement index and mean duration of uninterrupted immobility were found to be predicted only by the schizophrenia subtype. Age, gender, duration of illness and chlorpromazine equivalents did not contribute to the variance of the activity data. A MANOVA demonstrated the significant differences in the 3 parameters between schizophrenia subtypes (p = 0.001). Patients with catatonic schizophrenia had lower activity levels, a lower movement index and a longer duration of immobility than those with paranoid schizophrenia. Conclusions: Schizophrenia subtypes can be differentiated using objective measures of quantitative motor activity. The increased duration of immobility appears to be the special feature of catatonic schizophrenia.