WHITE MATTER INTEGRITY AND OLFACTORY FUNCTION IN MILD COGNITIVE IMPAIRMENT: PRELIMINARY STUDY

Abstract

Increasing evidence suggests that olfactory impairment is associated with an increased risk of conversion from mild cognitive impairment (MCI) to Alzheimer's disease. To explore how olfactory performance relate to white matter (WM) integrity, diffusion tensor imaging (DTI) was acquired from individuals with mild cognitive impairment (MCI). DTI was performed from thirteen individuals with MCI (mean age: 68.31 ± 8.83 years). Olfactory performance was assessed using the Brief Smell Identification Test (B-SIT). Cross-sectional voxel-wise analyses of relationships between B-SIT and DTI indices were performed using tract-based spatial statistics. Higher B-SIT scores were associated with lower mean diffusivity (MD) in areas such as the body and splenium of corpus callosum, right posterior thalamic radiation, superior corona radiata, internal and external capsules, sagittal stratum, frontal WM, right precuneus WM, and right temporal WM, while B-SIT scores were not significantly associated with fractional anisotropy across all MCI participants. In individuals with MCI, lower olfactory identification is associated with alterations in WM integrity expressed as a lower MD value. These cross-sectional preliminary studies suggest that olfactory impairment contributes to WM microstructural alterations in individuals with MCI. To clarify our results, further investigations in larger samples are required.