- Mild disease (MMSE 20-26) but presently pejorative outcome: relatively young subject (<80 years), "rapid" cognitive decline and high CSF tau rate (> 600pg / mL, for A diagnostic threshold of Alzheimer's disease of 450pg / mL). The evaluation of the pejorative evolution will be validated by the Committee of Experts of the Memory Center (IM2A at Pitié-Salpêtrière Hospital)