Prefrontal hemodynamic response to verbal-fluency task and hyperventilation in bipolar disorder measured by multi-channel near-infrared spectroscopy.
BACKGROUND
Many neuroimaging studies of patients with bipolar disorder have demonstrated functional hypofrontality (reduced activation of the frontal cortex), although this finding is still controversial. We previously found hypoactivation of the left prefrontal region in remitted subjects with bipolar disorder measured by one-channel near-infrared spectroscopy (NIRS). The aim of the present study was to clarify whether or not this finding was due to altered cerebral lateralization or caused by reduced cerebrovascular reactivity.


METHODS
We enrolled nine remitted patients with bipolar disorder and nine normal controls. Hemodynamic responses in the prefrontal cortex during the verbal-fluency and hyperventilation tasks were monitored by 24-channel NIRS, which can measure oxygenated hemoglobin (OxyHb), deoxygenated hemoglobin, and total hemoglobin (TotalHb).


RESULTS
The increases of OxyHb and TotalHb in the bipolar group were significantly smaller than that in the controls during the verbal-fluency task. The response of TotalHb during hyperventilation in the bipolar group was weaker than that in the controls.


CONCLUSIONS
The sample size was small.


CONCLUSIONS
These findings suggest that the bilateral hypofrontality to a cognitive task is seen in remitted subjects with bipolar disorder, which may be related to vascular function as measured by the response to hyperventilation.
Matsuo
Koji
K
Department of Neuropsychiatry, Graduate School of Medicine, University of Tokyo, Tokyo, Japan. matsuo-tky@umin.ac.jp <matsuo-tky@umin.ac.jp>
Watanabe
Akira
A
Onodera
Yoichi
Y
Kato
Nobumasa
N
Kato
Tadafumi
T
D000328:Adult; D000368:Aged; D001714:Bipolar Disorder / Q000503:physiopathology* / Q000523:psychology; D016022:Case-Control Studies; D003071:Cognition; D005260:Female; D006439:Hemodynamics; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D006985:Hyperventilation; D008297:Male; D008875:Middle Aged; D017397:Prefrontal Cortex / Q000098:blood supply*; D012039:Regional Blood Flow; D019265:Spectroscopy, Near-Infrared; D013060:Speech; D013647:Task Performance and Analysis
D006454:Hemoglobins