Implicit and explicit learning in schizophrenics treated with olanzapine and with classic neuroleptics.
OBJECTIVE
Novel and classic neuroleptics differ in their effects on limbic striatal/nucleus accumbens (NA) and prefrontal cortex (PFC) dopamine turnover, suggesting differential effects on implicit and explicit learning as well as on anhedonia. The present study investigates whether such differences can be demonstrated in a naturalistic sample of schizophrenic patients.


METHODS
Twenty-five inpatients diagnosed with DSM-IV schizophrenic psychosis and treated for at least 14 days with the novel neuroleptic olanzapine were compared with 25 schizophrenics taking classic neuroleptics and with 25 healthy controls, matched by age and education level. PFC/NA-dependent implicit learning was assessed by a serial reaction time task (SRTT) and compared with cerebellum-mediated classical eye-blink conditioning and explicit visuospatial memory. Anhedonia was measured with the Snaith-Hamilton-Pleasure Scale (SHAPS).


RESULTS
Implicit (SRTT) and psychomotor speed, but not explicit (visuospatial) learning were superior in the olanzapine-treated group as compared to the patients on classic neuroleptics. Compared to healthy controls, olanzapine-treated schizophrenics showed similar implicit learning, but reduced explicit (visuospatial) memory performance. Acquisition of eyeblink conditioning was not different between the three groups. There was no difference with regard to anhedonia and SANS scores between the patients.


CONCLUSIONS
Olanzapine seems to interfere less with unattended learning and motor speed than classical neuroleptics. In daily life, this may translate into better adaptation to a rapidly changing environment. The effects seem specific, as in explicit learning and eyeblink conditioning no difference to classic NL was found.
Stevens
Andreas
A
Department of Psychiatry, Osianderstrasse 22, 72076 Tuebingen, Germany. andreas.stevens@med.uni-tuebingen.de
Schwarz
Jürgen
J
Schwarz
Benedikt
B
Ruf
Ilona
I
Kolter
Thomas
T
Czekalla
Joerg
J
D000328:Adult; D000704:Analysis of Variance; D014150:Antipsychotic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001569:Benzodiazepines; D003213:Conditioning, Psychological / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D007858:Learning / Q000187:drug effects* / Q000502:physiology; D008297:Male; D000077152:Olanzapine; D010890:Pirenzepine / Q000031:analogs & derivatives* / Q000494:pharmacology* / Q000627:therapeutic use; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012559:Schizophrenia / Q000188:drug therapy* / Q000503:physiopathology
D014150:Antipsychotic Agents; D001569:Benzodiazepines; D010890:Pirenzepine; D000077152:Olanzapine