title: Olfaction, "olfiction," and the schizophrenia-spectrum: an updated meta-analysis on identification and acuity.
abstract: Olfaction deficits in individuals with schizophrenia are well documented. A meta-analysis conducted nearly a dozen years ago on the topic revealed a deficit of a full standard deviation in magnitude compared to nonpatient controls. Recent efforts have been attempted to determine whether deficits in olfactory identification and acuity reflect a vulnerability marker of schizophrenia-spectrum pathology. To address this issue, the present study conducted a meta-analysis of 16 studies of individuals with schizotypy, defined in terms of a) "ultra-high risk" status, b) having an affected biological family member, or c) having extreme scores on a schizotypy questionnaire. We also conducted an updated meta-analysis of 40 studies of olfactory functioning in schizophrenia. Consistent with the prior meta-analysis, patients with schizophrenia showed impairments in olfaction identification on a full standard deviation in magnitude (d = -.99). Individuals with schizotypy showed much more subtle (d = -.24) differences in olfaction, though the effect sizes were higher for studies examining individuals at "ultra-high risk" (d = -.67) versus studies examining individuals with psychometrically-defined (d = -.14) schizotypy. Differences in olfactory acuity, relative to their respective control groups, were small for both the schizophrenia (d = -.45) and schizotypy (d = -.38) studies but were similar in magnitude. The present findings argue against the notion that deficits in olfaction identification are a vulnerability marker of schizophrenia. Suggestions for future research are recommended.
authors.affiliation: Department of Psychology, Louisiana State University, Baton Rouge, LA 708080, United States. acohen@lsu.edu
authors.forename: Alex S
authors.initials: AS
authors.lastname: Cohen
authors.forename: Laura A
authors.initials: LA
authors.lastname: Brown
authors.forename: Tracey L
authors.initials: TL
authors.lastname: Auster
mesh_terms: D016206:Databases, Bibliographic / Q000706:statistics & numerical data; D006801:Humans; D000857:Olfaction Disorders / Q000175:diagnosis / Q000209:etiology*; D011594:Psychometrics; D012559:Schizophrenia / Q000150:complications*; D012569:Schizotypal Personality Disorder / Q000150:complications*; D012684:Sensory Thresholds; D012903:Smell / Q000502:physiology*; D011795:Surveys and Questionnaires