Human reward system activation is modulated by a single dose of olanzapine in healthy subjects in an event-related, double-blind, placebo-controlled fMRI study.
BACKGROUND
Olanzapine is a neuroleptic drug widely prescribed to treat schizophrenia and bipolar disorder. Although it is long known that modulation of the dopamine system is a basic mechanism of action of neuroleptics, their impact on reward functions mediated by dopamine is still poorly understood.


OBJECTIVE
Using functional magnetic resonance imaging (fMRI), we intended to reveal the effects of a single dose of olanzapine on reward-related brain activation.


METHODS
Eight healthy subjects were each scanned twice, once 5 h after intake of 5 mg of olanzapine and once after intake of placebo in a double-blind cross-over design. Subjects performed a delayed incentive paradigm with monetary reward to investigate reward functions and a breath-holding task as a hypercapnic challenge to reveal unspecific drug effects on the fMRI signal.


RESULTS
Reward-related brain activation in the ventral striatum, anterior cingulate and inferior frontal cortex was reduced on olanzapine compared to placebo. Only the differential effects (high>no reward) in the ventral striatum were independent of overall drug effects as measured with the breath-holding task. Parallel to the differential effects in the ventral striatum, the acceleration of reaction times in the trials with higher rewards was diminished in the olanzapine sessions.


CONCLUSIONS
Our behavioural and fMRI results can be interpreted as first evidence from neuroimaging that olanzapine affects the assignment of incentive salience represented by differential activation in dopaminergic brain areas and acceleration of reaction times. This can help to better understand neuroleptic effects in psychiatric diseases. Furthermore, we demonstrate the value of a hypercapnic challenge in functional pharmaco-MRI.
Abler
Birgit
B
Department of Psychiatry, University of Ulm, Leimgrubenweg 12-14, 89075, Ulm, Germany. birgit.abler@uni-ulm.de
Erk
Susanne
S
Walter
Henrik
H
D014150:Antipsychotic Agents / Q000494:pharmacology*; D001479:Basal Ganglia / Q000187:drug effects / Q000378:metabolism; D001569:Benzodiazepines / Q000494:pharmacology; D001921:Brain / Q000098:blood supply / Q000187:drug effects* / Q000378:metabolism; D002560:Cerebrovascular Circulation; D018592:Cross-Over Studies; D004298:Dopamine / Q000378:metabolism*; D004311:Double-Blind Method; D006801:Humans; D006935:Hypercapnia / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods; D009042:Motivation; D000077152:Olanzapine; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption; D010865:Pilot Projects; D017397:Prefrontal Cortex / Q000187:drug effects / Q000378:metabolism; D011930:Reaction Time / Q000187:drug effects; D012016:Reference Values; D012201:Reward; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology*
D014150:Antipsychotic Agents; D001569:Benzodiazepines; D004298:Dopamine; D000077152:Olanzapine; D010100:Oxygen; D017367:Selective Serotonin Reuptake Inhibitors