[Analysis of reaction time in post-acute schizophrenia using electrophysiologic variables]

20 postacute schizophrenic patients with predominantly negative symptoms and 21 age and sex matched normal controls were investigated in a P300 paradigm with simultaneous measurement of EP, EMG and behavioural reaction time. The steps of central information processing were operationalized by the following measures: input processing time (IPT): N1-latency; central processing time (CPT): N1-latency until EMG-onset; motor execution time (MET): EMG-onset until onset of target behaviour. For the schizophrenic group we found a pattern of significant deviations with reduction of the N1-, N2- and P3-amplitude, prolongation of the central processing, motor execution and behavioural termination time. The largest loss of time however was found for the central information processing time (203.1 +/- 72.9 vs. 113.1 vs. 20.2 ms, p = 0.000). In the control group the EMG reaction started 12.4 ms before the N2 peak, in the schizophrenic group 63.5 ms after the N2 peak (p = 0.02). Summing up, these findings are compatible with the assumption of a multiple functional deficit of central information processing in schizophrenia.