Deficits in inferior frontal cortex activation in euthymic bipolar disorder patients during a response inhibition task.
OBJECTIVE
The inferior frontal cortical-striatal network plays an integral role in response inhibition in normal populations. While inferior frontal cortex (IFC) impairment has been reported in mania, this study explored whether this dysfunction persists in euthymia.


METHODS
Functional magnetic resonance imaging (fMRI) activation was evaluated in 32 euthymic patients with bipolar I disorder and 30 healthy subjects while performing the Go/NoGo response inhibition task. Behavioral data were collected to evaluate accuracy and response time. Within-group and between-group comparisons of activation were conducted using whole-brain analyses to probe significant group differences in neural function.


RESULTS
Both groups activated bilateral IFC. However, between-group comparisons showed a significantly reduced activation in this brain region in euthymic patients with bipolar disorder compared to healthy subjects. Other frontal and basal ganglia regions involved in response inhibition were additionally significantly reduced in bipolar disorder patients, in both the medicated and the unmedicated subgroups. No areas of greater activation were observed in bipolar disorder patients versus healthy subjects.


CONCLUSIONS
Bipolar disorder patients, even during euthymia, have a persistent reduction in activation of brain regions involved in response inhibition, suggesting that reduced activation in the orbitofrontal cortex and striatum is not solely related to the state of mania. These findings may represent underlying trait abnormalities in bipolar disorder.
Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA 90095-7057, USA.
Jennifer D
JD
Townsend
Susan Y
SY
Bookheimer
Lara C
LC
Foland-Ross
Teena D
TD
Moody
Naomi I
NI
Eisenberger
Jeffrey S
JS
Fischer
Mark S
MS
Cohen
Catherine A
CA
Sugar
Lori L
LL
Altshuler
D000328:Adult; D001479:Basal Ganglia / Q000503:physiopathology*; D001714:Bipolar Disorder / Q000503:physiopathology*; D001931:Brain Mapping; D016022:Case-Control Studies; D005260:Female; D059907:Functional Neuroimaging; D006801:Humans; D007266:Inhibition, Psychological; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D017397:Prefrontal Cortex / Q000503:physiopathology*