No association between psychometrically-determined schizotypy and olfactory identification ability in first-degree relatives of patients with schizophrenia and non-psychiatric controls.

Objective: This study examined potential associations between schizotypy--including positive, negative, and disorganized domains--and olfactory identification ability. Based on a prior report (Park, S., Schoppe, S., 1997. Olfactory identification deficit in relation to schizotypy. Schizophr. Res. 26, 191-197), it was hypothesized that positive and negative schizotypy would be associated with poorer olfactory identification ability, at least among male participants.

Method: As part of a larger study, the Schizotypal Personality Questionnaire (SPQ) and University of Pennsylvania Smell Identification Test (UPSIT) were administered to 98 participants, including 44 healthy first-degree relatives of individuals with schizophrenia and related disorders and 54 non-psychiatric controls. Potential associations between SPQ subscales and UPSIT score were examined while considering the effects of sociodemographic variables on these measures.

Results: SPQ and UPSIT scores were not significantly different in first-degree relatives and controls. There was no evidence of an association between SPQ domains and UPSIT score, even when controlling for possible confounding variables, including age and educational attainment.

Conclusions: The nascent literature on potential associations between schizotypy and olfactory identification ability has yielded mixed findings to date. The current study does not support a correlation between these two markers, and this lack of association--in addition to equal olfactory identification performance in relatives and controls--casts doubt on the utility of the UPSIT as a measure of an endophenotypic trait. Future research would benefit from larger, more diverse samples; the addition of objective, interviewer-based measures of schizotypy; and attention to potentially confounding sociodemographic variables.