Associations between olfactory identification and verbal memory in patients with schizophrenia, first-degree relatives, and non-psychiatric controls

Objective: Olfactory identification deficits and verbal memory impairments may represent trait markers for schizophrenia. The aims of this study were to: (1) assess olfactory identification in patients, first-degree relatives, and non-psychiatric controls, (2) determine differences in verbal memory functioning in these three groups, and (3) study correlations between olfactory identification and three specific verbal memory domains. Method: A total of 106 participants-41 patients with schizophrenia or related disorders, 27 relatives, and 38 controls-were assessed with the University of Pennsylvania Smell Identification Test (UPSIT) and the Wechsler Memory Scale-Third Edition. Linear mixed models, accounting for clustering within families and relevant covariates, were used to compare scores across groups and to examine associations between olfactory identification ability and the three verbal memory domains. Results: A group effect was apparent for all four measures, and relatives scored midway between patients and controls on all three memory domains. UPSIT scores were significantly correlated with all three forms of verbal memory. Age, verbal working memory, and auditory recognition delayed memory were independently predictive of UPSIT scores. Conclusions: Impairments in olfactory identification and verbal memory appear to represent two correlated risk markers for schizophrenia, and frontal-temporal deficits likely account for both impairments. (c) 2006 Elsevier B.V. All rights reserved.