Sex-dependency of the Examination of Near-infrared Spectroscopy in Patient with Halitosis

anatomical difference between the brains of both sexes has been reported; specifically, that the cortex is thicker in women than in men（9）. This is considered to be one of the factors affecting the NIRS dataset. Women are also known to be more prone to depression than men（10, 11）. The tendency to become depressed seems to be related to attention, concentration, judgment, and reduced memory, and there may also sex-related differences in human cognitive function. Thus, it was hypothesized that sex differences also appear in Abstract The data on near-infrared spectroscopy（NIRS）corresponding to the left dorsolateral prefrontal cortex can be used as diagnostic criterion for psychological halitosis. Howev-er, it is unclear how sex differences affect them. Thus, this study aimed to investigate the influence of the differences between sexes using NIRS to diagnose psychological halitosis. The study included 42 patients（21 men and 21 women）with presumed psychological halitosis. All patients underwent volatile sulfur compounds（VSC）concentration analysis and psychological testing. They were investigated using NIRS during the performance of the verbal fluency task. Although 16 channels were measured in total, and the channels 13, 14, and 16 that corresponded to the left dorsolateral prefrontal cortex were analyzed. The results demonstrated that no significant differences were observed between VSC and psychological tests. The integral values and initial activation on the NIRS were significantly higher in men; thus, sex differences were observed. In conclu-sion, the present study suggests that sex differences should be considered when using NIRS as a diagnostic tool for patients with psychological halitosis.