The nature of abnormal language processing in euthymic bipolar I disorder: evidence for a relationship between task demand and prefrontal function.
OBJECTIVE
Abnormal language processing is a consistent finding in bipolar disorder (BD). We used functional magnetic resonance imaging (fMRI) to investigate the core components of language processing as well as the impact of task demand in a group of bipolar subjects.


METHODS
Twelve euthymic dextral male BD I participants receiving lithium monotherapy were matched with 12 controls. Groups were matched for age, years of education and estimated premorbid IQ. We employed a factorial design manipulating task demand (decision versus fluency) and task domain (phonetic versus semantic) to investigate differences in language processing between groups and across different task domains and requirements. Data were fitted to haemodynamic response models convolved to the experimental design. Group and task difference maps were generated.


RESULTS
During the scanning session bipolar patients demonstrated significantly slower reaction times. However, groups demonstrated the same task accuracy except for one domain (phonetic decision). All participants activated regions known to be engaged by language tasks, but compared to controls the bipolar patients showed altered patterns of prefrontal activation which were related to the nature of the task, language processing, and increasing task demand.


CONCLUSIONS
We have demonstrated abnormal prefrontal activation in bipolar patients across a range of language tasks with varying task demands.
Curtis
Vivienne A
VA
Division of Psychological Medicine, Institute of Psychiatry, London, UK. v.curtis@iop.kcl.ac.uk
Thompson
Jill M
JM
Seal
Marc L
ML
Monks
Paul J
PJ
Lloyd
Adrian J
AJ
Harrison
Louise
L
Brammer
Michael J
MJ
Williams
Steve C R
SC
Murray
Robin M
RM
Young
Allan H
AH
Ferrier
I Nicol
IN
D000328:Adult; D001288:Attention / Q000502:physiology*; D001714:Bipolar Disorder / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D001921:Brain / Q000098:blood supply / Q000503:physiopathology*; D001931:Brain Mapping; D003657:Decision Making / Q000502:physiology*; D004292:Dominance, Cerebral / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D010700:Phonetics; D017397:Prefrontal Cortex / Q000098:blood supply / Q000503:physiopathology*; D011930:Reaction Time / Q000502:physiology; D011932:Reading; D012660:Semantics; D014705:Verbal Behavior / Q000502:physiology*