Decreased cerebral haemodynamic response to cognitive and physiological tasks in mood disorders as shown by near-infrared spectroscopy.
BACKGROUND
Hypofrontality has been demonstrated in mood disorders by functional brain imaging methods such as positron emission tomography. However, the neurobiological basis of hypofrontality has not been well clarified. Near-infrared spectroscopy (NIRS) is a non-invasive technique for continuous monitoring of alterations in oxygenated (oxyHb) and deoxygenated (deoxyHb) haemoglobin using near-infrared light, which penetrates biological tissues.


METHODS
We used NIRS during cognitive and physiological tasks to investigate alterations of haemoglobin oxygenation in the frontal region of euthymic patients with mood disorders (major depressive disorder (MD) and bipolar disorder (BP)) and in controls.


RESULTS
The increase of oxyHb during a verbal fluency task was significantly less in the MD and the BP groups than in the controls. The MD group showed a significantly smaller decrease of oxyHb during hyperventilation than the controls. The BP group also showed a similar trend.


CONCLUSIONS
These findings suggest that the hypofrontality in mood disorders may be associated with a poor response in the cerebral blood vessels to neuronal and chemical stimuli.
Matsuo
K
K
Department of Psychiatry, JR Tokyo General Hospital, Japan.
Kato
N
N
Kato
T
T
D000328:Adult; D000368:Aged; D001714:Bipolar Disorder / Q000378:metabolism / Q000503:physiopathology / Q000523:psychology; D002560:Cerebrovascular Circulation; D003071:Cognition; D003865:Major Depressive Disorder / Q000378:metabolism / Q000503:physiopathology / Q000523:psychology; D005260:Female; D005625:Frontal Lobe / Q000098:blood supply / Q000378:metabolism*; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D019964:Mood Disorders / Q000378:metabolism* / Q000503:physiopathology* / Q000523:psychology; D009483:Neuropsychological Tests; D019265:Spectroscopy, Near-Infrared; D013647:Task Performance and Analysis
D006454:Hemoglobins