title: Association of Odor Thresholds and Responses in Cerebral Blood Flow of the Prefrontal Area during Olfactory Stimulation in Patients with Multiple Chemical Sensitivity.
abstract: Multiple chemical sensitivity (MCS) is a disorder characterized by nonspecific and recurrent symptoms from various organ systems associated with exposure to low levels of chemicals. Patients with MCS process odors differently than controls do. Previously, we suggested that this odor processing was associated with increased regional cerebral blood flow (rCBF) in the prefrontal area during olfactory stimulation using near-infrared spectroscopic (NIRS) imaging. The aim of this study was to investigate the association of odor thresholds and changes in rCBF during olfactory stimulation at odor threshold levels in patients with MCS. We investigated changes in the prefrontal area using NIRS imaging and a T&T olfactometer during olfactory stimulation with two different odorants (sweet and fecal) at three concentrations (zero, odor recognition threshold, and normal perceived odor level) in 10 patients with MCS and six controls. The T&T olfactometer threshold test and subjective assessment of irritating and hedonic odors were also performed. The results indicated that the scores for both unpleasant and pungent odors were significantly higher for those for sweet odors at the normal perceived level in patients with MCS than in controls. The brain responses at the recognition threshold (fecal odor) and normal perceived levels (sweet and fecal odors) were stronger in patients with MCS than in controls. However, significant differences in the odor detection and recognition thresholds and odor intensity score between the two groups were not observed. These brain responses may involve cognitive and memory processing systems during past exposure to chemicals. Further research regarding the cognitive features of sensory perception and memory due to past exposure to chemicals and their associations with MCS symptoms is needed.
authors.affiliation: Department of Environmental Medicine and Behavioral Science, Kindai University Faculty of Medicine, Osakasayama, Osaka, Japan.|Sick-house Medical Science Laboratory, Division of Basic Research, Louis Pasteur Center for Medical Research, Kyoto, Japan.
authors.forename: Kenichi
authors.identifier: http://orcid.org/0000-0002-6382-9807
authors.initials: K
authors.lastname: Azuma
authors.affiliation: Sick-house Medical Science Laboratory, Division of Basic Research, Louis Pasteur Center for Medical Research, Kyoto, Japan.|Outpatient Department of Sick-house Syndrome, Hyakumanben Clinic, Kyoto, Japan.
authors.forename: Iwao
authors.initials: I
authors.lastname: Uchiyama
authors.affiliation: Clinical Immune Function Laboratory, Division of Basic Research, Louis Pasteur Center for Medical Research, Kyoto, Japan.|Division of Internal Medicine, Hyakumanben Clinic, Kyoto, Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Tanigawa
authors.affiliation: Faculty of Education, Home Economics, Tokyo Gakugei University, Koganei, Tokyo, Japan.
authors.forename: Ikuko
authors.initials: I
authors.lastname: Bamba
authors.affiliation: Department of Human Environmental Design, Faculty of Health Science, Kio University, Kitakatsuragi-gun, Nara, Japan.
authors.forename: Michiyo
authors.initials: M
authors.lastname: Azuma
authors.affiliation: Department of Environmental Engineering, Graduate School of Engineering, Kyoto University, Kyoto, Japan.
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Takano
authors.affiliation: Department of Internal Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Yoshikawa
authors.affiliation: Department of Anatomy and Cellular Biology, Tokai University School of Medicine, Isehara, Kanagawa, Japan.
authors.forename: Kou
authors.initials: K
authors.lastname: Sakabe
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018777:Multiple Chemical Sensitivity / Q000503:physiopathology* / Q000523:psychology; D009812:Odorants; D064367:Olfactometry; D017397:Prefrontal Cortex / Q000098:blood supply*; D012684:Sensory Thresholds; D019265:Spectroscopy, Near-Infrared