Reduced prefrontal oxygenation in Alzheimer disease during verbal fluency tasks.
OBJECTIVE
Near-infrared spectroscopy (NIRS) is an optical method to measure changes in the concentration of oxygenated hemoglobin (O(2)Hb) and deoxygenated hemoglobin (HHb) in the vascular system of the brain tissue. Because NIRS is easy to assess and does not have any side effects, it seems perfectly suitable for functional measurements in psychiatric patients or fragile subjects. As previous research suggested changes in functional brain activation in prefrontal brain areas of patients with dementia, the aim of this study was to replicate these findings by means of multichannel NIRS.


METHODS
In the present study, the authors investigated 16 patients with Alzheimer disease and 16 healthy subjects (similar in age and sex) during performance of a verbal fluency task.


RESULTS
The results clearly showed an activation pattern during active phase as compared to baseline phase in the form of decreases in HHb and increases in O(2)Hb, with a reduced increase of O(2)Hb for patients.


CONCLUSIONS
These results indicate a diminished activation of the dorsolateral prefrontal cortex in patients with Alzheimer disease. Future research has to show whether this decreased activation pattern might be a suitable predictor for the effectiveness of treatment in dementias.
Herrmann
Martin J
MJ
University Hospital of Psychiatry and Psychotherapy, University of Würzburg, Germany. herrmann_m@klinik.uni-wuerzburg.de
Langer
Julia B M
JB
Jacob
Christian
C
Ehlis
Ann-Christine
AC
Fallgatter
Andreas J
AJ
D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000378:metabolism* / Q000523:psychology; D001931:Brain Mapping; D002560:Cerebrovascular Circulation; D005260:Female; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D010100:Oxygen / Q000378:metabolism*; D010108:Oxyhemoglobins / Q000378:metabolism; D017397:Prefrontal Cortex / Q000098:blood supply / Q000378:metabolism*; D012720:Severity of Illness Index; D019265:Spectroscopy, Near-Infrared; D013647:Task Performance and Analysis; D014706:Verbal Learning / Q000502:physiology
D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin; D010100:Oxygen