Effects of quetiapine on cognitive functions in schizophrenic patients: a preliminary single-trial ERP analysis

The study aimed to explore by means of single-trial event-related potentials (ERPs), whether and how the medication change from older neuroleptics to quetiapine in schizophrenic patients led to a significant cognitive enhancement. This single-trial ERP analysis helps to investigate attention and memory processes in the single patient before and after treatment.

Thirteen schizophrenic patients (mean age: 40.1+/-13.5 years) were followed up for 16 weeks and assessed for changes of clinical symptoms and ERP components P300 representing target detection processes and N400 indexing context integration in word recognition processes. Three subjects had to be excluded from the ERP recording sessions because of excessive blink artefacts and movements.

Regarding the P300 components of the target detection, there were significant increases of amplitudes in 5 of 10 patients (50%) at week 16 comparing with week 0. Regarding the N400 components of the word recognition, there were significant increases of amplitudes in 4 of 10 patients (40%) at week 16 comparing with week 0.

The mean scores of PANSS, MADRS, Bf-S, SCL-90 and CGI-S at the end of study (week 16) showed significant improvements compared to the baselines (week 0) (p<0.05). During the study, no extrapyramidal symptoms as well as akathisia were reported after quetiapine treatment. These preliminary data suggest that quetiapine might partially improve the cognitive functions in the context integration and target detection processing in these patients. This technical procedure (single-trial ERP) may help to differentially assess cognitive enhancements in each single patient under treatment.