Sleep complaints are associated with reduced left prefrontal activation during a verbal fluency task in patients with major depression: A multi-channel near-infrared spectroscopy study

Background Recent studies have indicated the potential clinical use of near-infrared spectroscopy (NIRS) as a tool for assisting in the diagnosis of major depressive disorder (MDD). Although sleep complaints are often manifested in MDD, no study has elucidated the possible association between the objective evaluation of sleep and NIRS signals in MDD. Methods Fourteen patients with MDD and 15 healthy controls wore waist actigraphy equipment before the NIRS scan to investigate sleep parameters. We performed a 52-channel NIRS scan and measured changes in oxygenated hemoglobin ([oxy-Hb]) during a verbal fluency task. Results In patients with MDD, a significant negative correlation was observed between the 17-item Hamilton Depressive Rating Scale score and cerebral reactivity of the right temporal region (p_s:=−0.804 to −0.762; FDR-corrected; p=0.008–0.012). The Pittsburgh Sleep Questionnaire Index, which enables assessment of continuous sleep quality and disturbances, was negatively correlated with [oxy-Hb] changes in the left prefrontal cortex (p_s=−0.630 to −0.551; FDR-corrected; p=0.043–0.048). Actigraphic sleep variables prior to the NIRS measurement showed no significant correlation with [oxy-Hb] changes. Limitations The limitations were small sample size with the low severity of depression and the use of actigraphy for only one night. Conclusion Self-rated sleep disturbance were associated with decreased left prefrontal reactivity during a verbal fluency task in patients with MDD. Our result indicates that the reactivity of the prefrontal region is susceptible to sleep complaints, providing further evidence to support potential clinical application of NIRS.