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.

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BackgroundNormal aging involves a decline in cognitive function that has been shown to correlate with volumetric change in the hippocampus, and with genetic variability in the APOE-gene. In the present study we utilize 3D MR imaging, genetic analysis and assessment of verbal memory function to investigate relationships between these factors in a sample of 170 healthy volunteers (age range 46–77 years).MethodsBrain morphometric analysis was performed with the automated segmentation work-flow implemented in FreeSurfer. Genetic analysis of the APOE genotype was determined with polymerase chain reaction (PCR) on DNA from whole-blood. All individuals were subjected to extensive neuropsychological testing, including the California Verbal Learning Test-II (CVLT). To obtain robust and easily interpretable relationships between explanatory variables and verbal memory function we applied the recent method of conditional inference trees in addition to scatterplot matrices and simple pairwise linear least-squares regression analysis.ResultsAPOE genotype had no significant impact on the CVLT results (scores on long delay free recall, CVLT-LD) or the ICV-normalized hippocampal volumes. Hippocampal volumes were found to decrease with age and a right-larger-than-left hippocampal asymmetry was also found. These findings are in accordance with previous studies. CVLT-LD score was shown to correlate with hippocampal volume. Multivariate conditional inference analysis showed that gender and left hippocampal volume largely dominated predictive values for CVLT-LD scores in our sample. Left hippocampal volume dominated predictive values for females but not for males. APOE genotype did not alter the model significantly, and age was only partly influencing the results.ConclusionGender and left hippocampal volumes are main predictors for verbal memory function in normal aging. APOE genotype did not affect the results in any part of our analysis.

Age-related change in episodic memory function is commonly reported in older adults. When detected on neuropsychological tests, it may still be difficult to distinguish normal from pathological changes. The present study investigates age-and sex-related changes in a group of healthy middle-aged and older adults, participating in a three-wave study on cognitive aging. The California Verbal Learning test (CVLT-II) was used to assess their episodic memory function. A cross-sectional analysis of results from the first wave showed higher performance in females than males, with a steeper age-related decline in males. This was confirmed in a longitudinal analysis using a mixed effects regression model, but with a lower age-related change and smaller difference between the sexes. Information about learning strategies and errors in the third wave turned out to contribute significantly to explain change in episodic memory function across the three waves. We argue that the results from the longitudinal analyses are generalizable to the population of healthy middle-aged and older individuals, and that they could be useful in guiding clinicians when evaluating individuals with respect to cognitive change.