APOE and Mental deterioration: 1. Greater decline in ADAS-Cog11 scores in both APOE ε4 carriers and non-carriers.2. Faster cognitive decline with lower CSF Aβ42 levels.3. More pronounced cognitive deterioration during the MCI stage; smaller baseline hippocampal volume but larger after normalization.4. Greater cognitive decline in APOEε4 positive MCI subjects.