Can the Assessment of the Subhippocampal Region Contribute to the Detection of Early Diagnosis of Alzheimer's Disease? A Validation Study Using PET With Florbetapir (AV-45).

Reliable diagnosis of Alzheimer's Disease (AD) at the predementia stage is currently considered to be a priority for research, as disease modifying therapies are being evaluated. Many studies focus on the functional and morphological assessment of the hippocampal formation. However, neurofibrillary tangles, associated with cognitive deficits, initially affect the anterior subhippocampal cortex (transentorhinal, entorhinal and perirhinal cortex) before reaching the hippocampus. Studies from our group have tried to investigate if the assessment of subhippocampal regions using cognitive tools and neuroimaging techniques could contribute to the diagnosis of AD at a very early stage. In a previous project, the investigators included 40 patients with single domain amnestic MCI (Mild Cognitive Impairment), known to be at high risk for AD and demonstrated that aMCI patients with a profile of subhippocampal dysfunction (impaired performance on a visual recognition memory task) display other clinical as well as imaging profiles of patients with early AD using MRI and SPECT. Longitudinal follow-up data in these patients is currently under way. Preliminary data indicates that evaluating the subhippocampal region using visual recognition tasks is highly predictive of AD over 6 years. The aim of this project is to obtain additional diagnostic data using a PET amyloid tracer (Florbetapir F18 AV45 F18), an in-vivo marker of one of the neuropathological lesions that define AD, of in order to enhance diagnostic accuracy AD in these patients. This approach will validate the hypothesis as to whether the assessment of subhippocampal dysfunction can contribute to the early diagnosis of AD.