Ron has a theoretical framework based on assumed etiology, with which he predicts (2) that:

• single-domain amnestic MCI (aMCI), i.e., memory impairment only, will progress to pure AD (if not caused by depression);
• multi-domain amnestic MCI will progress to AD plus vascular dementia (if not caused by depression);
• non-amnestic MCI will progress to non-AD dementias.

Ron showed a graph on the slide "MCI: Conversion to Dementia" (3), which shows:

• 35 percent of non-ApoE4 carriers will progress to dementia in three years;
• 90+ percent of ApoE4 carriers will progress to dementia (still progressing at four years).

ADNI partners (and others) are researching biomarkers for earlier/better prediction of conversion (4-6). Various cerebrospinal fluid (CSF) biomarkers and changes in brain-region sizes from neuroimaging seem to have predictive power (7).

References:
1. Petersen, R. Mild Cognitive Impairment. CONTINUUM: Lifelong Learning in Neurology. Dementia. 13(2):15-38, April 2007. Abstract

2. Edited by Ronald C. Petersen. Mild Cognitive Impairment: Aging to Alzheimer's Disease. Oxford University Press, USA; first edition January 9, 2003.

3. Petersen, Ronald C. Mild Cognitive Impairment: The Current Status. Talk at 10th Annual Updates on Dementia conference, Stanford University, June 4, 2008.

4. Antecedent Biomarkers for the Early and Preclinical Detection of Alzheimer's Disease

5. ADNI: GWA Nearly Complete, Biomarker Analysis Update

6. ADNI: Mission Creep From Alzheimer Disease to Healthy Senior?

7. Beckett, Laurel, ADNI Biostatistics Core, director. Private communication.

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