Recently revised Alzheimer Disease (AD) diagnostic1described nonamnestic presentations: 1/
language presentation (logopenic progressive aphasia) 2/ visuospatial presentation (posterior
cortical atrophy or PCA) and 3/ executive dysfunction. AD pathological changes may precede
the clinical diagnosis of dementia of AD type for a while2. Biomarkers have been developed:
biomarkers of brain amyloid-beta (Aß) (CerebroSpinal Fluid CSF concentration ßamyloid,
molecular imaging with amyloid targeted PET ligands), biomarkers of neural degeneration (MRI
hippocampal volume, regional metabolism as assessed by PET with [18F]-FDG) and may be used to
made early detection of the neuropathology associated with AD Even if CSF biomarkers (tau,
p-tau and β amyloïd are interesting to improve diagnosis of AD, they cannot provide
topographic information. PET tau imaging seems to be promise to evaluate quantitative and
spatial assessment of tau lesions both in AD and fronto-temporal lobar dementia.
The hypothesis of the research is that it exists a different regional pattern of tracer
retention across brain regions according to clinical symptoms : temporal for logopenic
aphasia and occipital for posterior cortical atrophy.