2010 年 69 巻 1 号 p. 1-15
Objective: Near-infrared spectroscopy (NIRS) has been increasingly employed in psychiatry for functional neuroimaging studies of sleepiness, fatigue, personality, aging, brain activation time course, transcranial magnetic stimulation effects, and psychiatric disorders such as schizophrenia, mood disorders, panic disorder, and eating disorder, owing to its advantages over fMRI and PET such as complete noninvasiveness, small apparatus for measurements, and the natural setting for its examination.
Methods: Characteristics of frontal lobe function were investigated using multichannel NIRS machines in schizophrenia, unipolar depression, and bipolar depression. Changes of oxygenated-hemoglobin concentration (oxy-Hb) were monitored every 0.1s during a verbal fluency task using a Hitachi ETG-100 and ETG-4000 system with the probes placed on the subjects' frontal and temporal regions.
Results: Three psychiatric groups demonstrated different patterns of oxy-Hb changes from those in the control group. The schizophrenic group was characterized by a reduced oxy-Hb increase during the task period followed by an oxy-Hb re-increase during the post-task period, the unipolar depression group by a smaller oxy-Hb increase, and the bipolar depression group by a comparable but delayed oxy-Hb increase.
Conclusion: The observed patterns of oxy-Hb changes suggest the characteristics of reactivity of frontal lobe function: inefficient, reduced, and preserved but delayed in schizophrenia, unipolar depression, and bipolar depression, respectively. NIRS can be employed as a clinical laboratory test for diagnosis and treatment of psychiatric disorders in the near future.