Objectives: This study aimed to examine the clinical outcomes of questionable dementia (QD) elderly subjects after three years of follow-up and to compare the ability of a standardized clinical assessment, neuropsychologic tests, the ApoE genotyping, and possible combinations of these methods to predict their progression to Alzheimer disease (AD).
Methods: One hundred six elderly subjects with QD were evaluated with a standardized clinical assessment, neuropsychologic tests, and ApoE genotyping and followed up annually. The Clinical Dementia Rating Sum of Boxes (CDR-SOB) score was used as a quantitative summary score of the standardized clinical assessment on the overall functioning of the subjects.
Results: Among the individuals remaining in the study after the 3-year follow-up period, 8.3% had improved to a state of normal cognition, 72.7% were still in the QD state. and 19.4% had progressed to clinically evident AD. Although each of CDR-SOB, Word List Recall (WLR), and ApoE epsilon4 genotype was predictive for AD, the combination of CDR-SOB and WLR was found to predict AD better than any single variable. However, the addition of the ApoE epsilon4 genotype information to CDR-SOB or WLR did not improve their predictive ability.
Conclusion: The combination of clinical assessment on function and episodic memory test can improve the predictive ability of each measure for progression to AD in QD individuals. However, ApoE genotyping dose not make an additional contribution to AD prediction in QD individuals when used in combination with clinical assessment or memory test.