Stroop performance in bipolar disorder: further evidence for abnormalities in the ventral prefrontal cortex.
OBJECTIVE
Bipolar patients are impaired in Stroop task performance, a measure of selective attention. Structural and functional abnormalities in task-associated regions, in particular the prefrontal cortex (PFC), have been reported in this population. We aimed to examine the relationship between functional abnormalities, impaired task performance and the severity of depressive symptoms in bipolar patients.


METHODS
Remitted bipolar patients (n = 10; all medicated), either euthymic or with subsyndromal depression, and age-matched control subjects (n = 11) viewed 10 alternating blocks of incongruent Stroop and control stimuli, naming the colour of the ink. Neural response was measured using functional magnetic resonance imaging. We computed between-group differences in neural response and within-group correlations with mood and anxiety.


RESULTS
There were no significant between-group differences in task performance. During the Stroop condition, controls demonstrated greater activation of visual and dorsolateral and ventrolateral prefrontal cortical areas; bipolar patients demonstrated relative deactivation within orbital and medial prefrontal cortices. Depression scores showed a trend towards a negative correlation with the magnitude of orbitofrontal cortex deactivation in bipolar patients, whereas state anxiety correlated positively with activation of dorsolateral PFC and precuneus in controls.


CONCLUSIONS
Our findings confirm previous reports of decreased ventral prefrontal activity during Stroop task performance in bipolar patients, and suggest a possible negative correlation between this and depression severity in bipolar patients. These findings further highlight the ventromedial PFC as a potential candidate for illness related dysfunction in bipolar disorder.
Kronhaus
Dina M
DM
Institute for Adaptive and Neural Computation, School of Informatics, The University of Edinburgh, Edinburgh, UK. dk323@cam.ac.uk
Lawrence
Natalia S
NS
Williams
Andrew M
AM
Frangou
Sophia
S
Brammer
Michael J
MJ
Williams
Steve C R
SC
Andrew
Christopher M
CM
Phillips
Mary L
ML
D000328:Adult; D000339:Affect / Q000502:physiology; D001288:Attention / Q000502:physiology*; D001714:Bipolar Disorder / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D001931:Brain Mapping; D003118:Color Perception / Q000502:physiology*; D003220:Conflict, Psychological; D005260:Female; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010101:Oxygen Consumption / Q000502:physiology; D017397:Prefrontal Cortex / Q000503:physiopathology*; D012660:Semantics; D013223:Statistics as Topic