Hippocampal Mean Diffusivity is a Biomarker of Neuronal Injury in Patients with Mild Cognitive Impairment and Alzheimer´s Disease Dementia (P6.212)

OBJECTIVE: To analyze Mean Diffusivity in Magnetic Resonance Imaging (MD-MRI) at areas of the medial temporal cortex, both in healthy controls and in patients with degenerative amnesic Mild Cognitive Impairment (aMCI) and Alzheimer’s Disease Dementia (ADD). BACKGROUND: Different areas of the medial temporal cortex are usually involved in Alzheimer’s Disease (AD). MD-MRI measurements enable the analysis of water movements at tissue level, and increased diffusivity is associated with the presence of microstructure damages. DESIGN/METHODS: Forty-eight individuals (age 74.71±7.18 years) [16 healthy control individuals, 15 patients with aMCI, and 17 patients with ADD], right-handed, paired by age and education level were included in the study. The findings of MD-MRI among the different groups were analyzed at the level of the hippocampus, the Parahippocampal Gyrus (PG), and the Entorhinal Cortex (EC) with ANOVA (post-hoc Bonferroni test). These findings were correlated with their performance at the California Verbal Learning Test (CVLT), with Pearson test. RESULTS: MD-MRI right hippocampus measurements enabled the identification of 3 groups (ADD-controls: p<0.001, ADD-aMCI: p<0,05, aMCI-controls: p<0.05), with ADD patients presenting with the highest values, and patients with aMCI with intermediate results. Significant differences were noted at the left hippocampus between ADD-aMCI patients (p<0.01) and ADD-controls (p<0.001), without significant differences noted between controls and aMCI patients. Differences were also noted among the groups at the left PG (ADD-controls: p<0.05), left EC (ADD-controls: p<0.05), and right EC (ADD-controls: p<0.01). When analyzing the 3 groups as a whole, the 6 areas assessed showed significant negative correlations between MD-MRI values and patient performance in CVLT coding and delay recall tests. CONCLUSIONS: MD-MRI at these areas revealed differences among the 3 groups, thus reflecting the progressive microstructure damage present throughout the AD spectrum. These findings were also evidenced by patients9 performance at the episodic memory tests based on these structures. Disclosure: Dr. DEMEY has nothing to disclose. Dr. Ventrice has nothing to disclose. Dr. Rojas has nothing to disclose. Dr. Allegri has nothing to disclose. Dr. Zubiri has nothing to disclose. Dr. Somale has nothing to disclose.