Differential frontal activation in schizophrenia and bipolar illness during verbal fluency.
BACKGROUND
The precise nature of frontal lobe dysfunction in schizophrenia remains unclear. We have previously demonstrated, using fMRI, a task-specific attenuation of frontal activation in schizophrenic patients. By using an identical methodology in matched bipolar subjects, we sought to determine whether this finding is specific to schizophrenia or a correlate of psychosis in general.


METHODS
Five dextral male bipolar patients and matching groups of schizophrenic subjects and controls were studied using fMRI. Echoplanar images were acquired while subjects performed two paced tasks: covert verbal fluency and a semantic decision task. Generic brain activation maps were constructed from individual images by sinusoidal regression analysis. Between-group differences in the mean power of experimental response were identified on a voxel-wise basis by an analysis of variance (ANOVA).


RESULTS
The bipolar patients showed extensive prefrontal activation during verbal fluency which was significantly greater than in controls. There was no difference in the prefrontal BOLD response during the semantic decision task.


CONCLUSIONS
These data indicate that bipolar patients show a strikingly different pattern of frontal responses compared to those with schizophrenia and provide further evidence that abnormal frontal activation in psychotic disorders is more apparent during verbal fluency than semantic decision.
Curtis
V A
VA
Department of Psychological Medicine, Institute of Psychiatry, De Crespigny Park, London SE5 8AF, UK. v.curtis@iop.kcl.ac.uk
Dixon
T A
TA
Morris
R G
RG
Bullmore
E T
ET
Brammer
M J
MJ
Williams
S C
SC
Sharma
T
T
Murray
R M
RM
McGuire
P K
PK
D000328:Adult; D001714:Bipolar Disorder / Q000175:diagnosis / Q000503:physiopathology*; D001931:Brain Mapping; D003657:Decision Making / Q000502:physiology; D004292:Dominance, Cerebral / Q000502:physiology; D017352:Echo-Planar Imaging; D005625:Frontal Lobe / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D012559:Schizophrenia / Q000175:diagnosis / Q000503:physiopathology*; D012660:Semantics; D014705:Verbal Behavior / Q000502:physiology