Oral health and changes in the brain

Inclusion criteria: I. 20 years of age or older at the time of obtaining consent. II. Subjects meeting the following conditions 1.Subjects with neurodegenerative disease 1) Subjects who can be accompanied by a legal guardian on the day of study participation at the NIRS. 2) Subjects meeting criteria of tauopathy. 2.Subjects with traumatic brain injury 1) Subjects who can be accompanied by a legal guardian on the day of study participation at the NIRS. 2) Subjects with ability to make informed consent. 3.Subjects with bipolar disorder 1) Subjects with ability to make informed consent. 2) Subjects meeting criteria of bipolar disorder. 4.Subjects with schizophrenia 1) Subjects with ability to make informed consent. 2) Subjects meeting criteria of schizophrenia. 5.Healthy volunteers 1) Subjects with ability to make informed consent. Exclusion criteria: I.Subjects with severe physical complications II.Subjects with claustrophobia III.Pregnant, possibly pregnant or lactating women IV.Subjects meeting the following conditions 1.Subjects with either neurodegenerative disease or traumatic brain injury 1)Subjects with neurodegenerative disease who have organic brain disorders 2)Subjects with neurodegenerative disease who have substance-related disorders 3)Subjects with traumatic brain injury who have any psychiatric diseases 4)From the standpoint of radiation exposure from a nuclear medicine scan, subjects who have participated in other nuclear medicine scans as healthy volunteers in the 6 months prior to the start of this study 5)Subjects who are considered to be inappropriate to participate in the study 2.Subjects with either bipolar disorder or schizophrenia 1)Subjects with other psychiatric diseases 2)Subjects with organic brain disorders 3)Subjects who have been taking papaverine or xanthine 4)Subjects with metallic medical device in the body who have bipolar disorder 5)Subjects with tattoo who have bipolar disorder 6)Subjects who tends to suicide 7)Subjects who are considered to be inappropriate to participate in the study 3.Healthy volunteers 1)Subjects with organic brain disorders 2)Subjects with substance-related disorders 3)Subjects with metallic medical device in the body 4)Subjects with tattoo 5)From the standpoint of radiation exposure from a nuclear medicine scan, subjects who have participated in other nuclear medicine scans as healthy volunteers in the 6 months prior to the start of this study 6)Subjects who are considered to be inappropriate to participate in the study