The evaluation of hemodynamic changes in the prefrontal cortex of bipolar depressive and major depressive disorders with near-infrared spectroscopy method

Objective: In this thesis; hemodynamic changes in the prefrontal cortex are examined by functional near-infrared spectroscopy during executive tests in healthy individuals, bipolar disorder and major depressive disorder groups in order to obtain distinctive diagnostic parameters. Method: A Functional near-infrared spectroscopy system has been developed to monitor hemodynamic changes in the prefrontal cortex. The software was prepared for two different executive tests. Hemodynamic changes in prefrontal cortex during the three different executive tests, (Wisconsin Card Sorting Test, Verbal Fluency Test, Stroop Test) were measured by the functional near-infrared spectroscopy system on 12 healthy individuals, 12 patients from the bipolar disorder-depressive period, 12 patients from major depressive disorders. Results: During executive tests, dorsolateral prefrontal cortex and ventrolateral prefrontal cortex areas exhibited hypoactivation in bipolar disorder–depressive period and major depressive disorder patients in comparison to healthy individuals. When this hypoactivation was examined based on the channels, specific findings for patients were observed. Conclusion: We revealed that functional near-infrared spectroscopy may identify differences between bipolar depressive disorder and major depressive disorder that has the potential to be used in a clinical setting for diagnostic purposes. Further studies with a higher number of participants are needed in order to obtain better diagnostic parameters. Key words: fNIRS, bipolar disorder, major depression, executive tests