title: Clinical correlates of olfactory hallucinations in schizophrenia.
abstract: OBJECTIVES. Olfactory hallucinations (OHs) are underrepresented in conventional clinical instruments, infrequently researched, and poorly understood. To advance understanding of OHs, we examined their past-month prevalence and co-occurring symptoms in two datasets. DESIGN. One dataset comprised categorical codes and was examined using homogeneity analysis and logistic regression; the other dataset comprised numeric ratings and was examined using principal components analyses and linear regression. METHOD. The two datasets included: (1) 962 cases with Present State Examination - 9th Edition (PSE-9), codes (recoded present/absent) from the World Health Organization 10 Country (WHO-10) Study and (2) 265 cases with ratings on Scales for Assessing Positive/Negative Symptoms of Schizophrenia (SAPS/SANS). Two PSE-9 items (external- and self-smells) were recoded into a single OH item to examine consistency with the SAPS/SANS dataset, which contained a single OH item. RESULTS. Prevalence of OHs and hallucinations in other modalities differed according to the WHO-10 international centre. Across centres, OHs were present in 13% of the WHO-10 dataset, similar to the 17% prevalence rate in the SAPS/SANS dataset. Referential/control delusions and other hallucinations (particularly, somatic/tactile/gustatory hallucinations) were significant independent correlates of OHs in both datasets. OHs also co-occurred with social anxiety and depression in the WHO-10 dataset, with self-smells being particularly associated with self-depreciation. CONCLUSIONS. Sociocultural factors may modulate the self-reporting and/or detection of OHs and hallucinations in other modalities. Referential/control delusions promote the generation and/or maintenance of OHs independent of factors shared with other hallucinations. OHs and hallucinations of taste, touch, and bodily sensation frequently co-occur. Self-smells warrant sensitive probing.
authors.affiliation: Macquarie Centre for Cognitive Science, Macquarie University, Sydney, New South Wales, Australia.
authors.forename: Robyn
authors.initials: R
authors.lastname: Langdon
authors.forename: Jonathan
authors.initials: J
authors.lastname: McGuire
authors.forename: Richard
authors.initials: R
authors.lastname: Stevenson
authors.forename: Stanley V
authors.initials: SV
authors.lastname: Catts
mesh_terms: D000293:Adolescent; D000328:Adult; D001008:Anxiety Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D002908:Chronic Disease; D015897:Comorbidity; D003431:Cross-Cultural Comparison; D003430:Cross-Sectional Studies; D003702:Delusions / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D003866:Depressive Disorder / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D005260:Female; D006212:Hallucinations / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology*; D006801:Humans; D008297:Male; D008609:Mental Status Schedule / Q000706:statistics & numerical data; D008875:Middle Aged; D010698:Phobic Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D011594:Psychometrics / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D012559:Schizophrenia / Q000175:diagnosis* / Q000453:epidemiology; D012565:Schizophrenic Psychology; D012649:Self Concept; D012903:Smell; D014944:World Health Organization; D055815:Young Adult