P8. Relationship of fornix white matter microstructure and memory function in older adults

Abstract

Degradation of brain white matter components is partly responsible for memory loss in the course of healthy aging. However, the exact tract parameters responsible for this deterioration need more investigation. From young adults, evidence suggests a relationship of white matter microstructure and memory components. However, studies with older adults are still scarce. In the present study, three main memory networks were reconstructed individually using probabilistic tractography: the parahippocampal cingulum, the uncinate fasciculus and the fornix. A sample of 30 older adults between the age of 50 and 79 years were administered an implicit learning and memory paradigm and diffusion tensor imaging (DTI) was performed to extract the fractional anisotropy (FA) and the mean diffusivity (MD) of each tract. Memory performance was assessed after the acquisition of the novel vocabulary. Association of tract parameters (adjusted for age) with memory performance were investigated. Consistent with previous evidence, FA was negatively and MD was positively related to higher age. In addition, lower memory performance was associated with fornix microstructure degradation, but not with other structural parameters such as parahippocampal, uncinate microstructure or volume. Our findings suggest that particularly fornix degradation is a predictor of age-related cognitive decline.