Unawareness of Olfactory Dysfunction and Its Association with Cognitive Functioning in Middle Aged and Old Adults

The objective of this study was (a) to investigate the accordance of self-reported and objectively assessed olfactory functioning and (b) to compare performance on cognitive tests of individuals unaware of their olfactory dysfunction with individuals aware of their olfactory status. Two hundred forty participants, constituting two age groups, were evaluated with the Scandinavian Odor Identification Test, a question of self-evaluated olfactory function, tests of cognitive function, and a memory questionnaire. The proportion of individuals being unaware of an olfactory dysfunction was high in both middle aged (86%) and old (78%) participants. Performance on neuropsychological tests showed that persons unaware of their olfactory dysfunction performed poorer on tests of verbal learning and memory and attention/processing speed compared to individuals aware of a normal olfactory status as well as individuals aware of their olfactory dysfunction. The clinical relevance of unawareness of olfactory dysfunction, as suggested earlier, needs further investigation and stresses the need of an extensive multi-modal and longitudinal assessment of unawareness of sensory and cognitive function to learn more about the facets of the concept of unawareness.