CAN DUAL TASK PARADIGMS CONTRIBUTE TO THE DIFFERENTIAL DIAGNOSIS BETWEEN DEPRESSION AND DEMENTIA/MCI?

Abstract

Serial position performance was measured with the Buschke selective reminding test (BSRT). Hippocampal size was automatically measured via MRI using high-dimensional spatial transformation and a predefined hippocampus mask. We conducted regression analyses with delayed primacy, delayed recency and total delayed recall performance as outcome variables; predictors were age, family history of Alzheimer’s disease (AD), APOE e4 status, sex, level of education, total intracranial volume, and left and right hippocampal size. Results: The size of both the left and right hippocampus was positively correlated with delayed primacy performance, although left hippocampal size was a slightly better predictor of performance. In contrast, hippocampal size did not predict total delayed recall or recency performance. Conclusions:These findings are consistent with the hypothesis that the hippocampus is involved in delayed primacy consolidation. To our knowledge, this is the first time this has been reported in cognitively-intact older individuals, using in-vivo imaging. Our results shed some light on the relationship between delayed primacy performance and generalised cognitive decline. Since delayed primacy consolidation relies on a healthy hippocampus, and the hippocampus is affected early in AD, it is possible that failure to consolidate delayed primacy items might indirectly signal the incipient emergence of the disease.