title: The effects of a sedative antihistamine, d-chlorpheniramine, on visuomotor spatial discrimination and regional brain activity as measured by positron emission tomography (PET).
abstract: Although most people taking antihistamines have experienced sedation and impaired performance, the neural correlates of these sedative properties are not well understood in man. Brain imaging can be used to demonstrate how regional brain activities are altered during such sedative effects. The aim of this study was to visualize the brain mechanism of impaired visuomotor spatial cognition with orally administered d-chlorpheniramine, a first-generation sedative antihistamine, using H(2) (15)O and positron emission tomography (PET). Normal subjects were randomly assigned to two groups (chlorpheniramine and placebo) and performed a spatial discrimination task after the oral administration of 6 mg d-chlorpheniramine or a placebo. The administration of d-chlorpheniramine impaired visuomotor spatial discrimination and altered cortical and subcortical activity. Decreased and increased activities were observed in the right parietal cortex (BA 40) which is related to visuomotor spatial cognition and the posterior cingulate cortex which constitutes the attention system of the brain, respectively. In particular, the brain activities of BA 40 were negatively and positively correlated to those of bilateral caudate nuclei and the dorsolateral prefrontal cortex, respectively. These findings clearly suggest that the alteration in the cortical and subcortical activity contributes to impaired spatial cognition caused by treatment with d-chlorpheniramine.
authors.affiliation: Department of Pharmacology, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Mochizuki
authors.forename: Manabu
authors.initials: M
authors.lastname: Tashiro
authors.forename: Masaaki
authors.initials: M
authors.lastname: Tagawa
authors.forename: Michiko
authors.initials: M
authors.lastname: Kano
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Itoh
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Okamura
authors.forename: Takehiko
authors.initials: T
authors.lastname: Watanabe
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Yanai
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D002744:Chlorpheniramine / Q000494:pharmacology*; D018592:Cross-Over Studies; D004192:Discrimination, Psychological / Q000187:drug effects*; D005403:Fixation, Ocular / Q000187:drug effects; D006634:Histamine H1 Antagonists / Q000494:pharmacology*; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D008297:Male; D011597:Psychomotor Performance / Q000187:drug effects*; D016037:Single-Blind Method; D013028:Space Perception / Q000187:drug effects*; D014055:Tomography, Emission-Computed
chemical_list: D006634:Histamine H1 Antagonists; D006993:Hypnotics and Sedatives; D002744:Chlorpheniramine