In this prospective longitudinal study, conducted in a large sample of
amnestic MCI patients over a three-year period, we investigated the recently advanced
proposal that unadjusted test scores obtained at baseline on long-term
memory tests are more reliable than age- and education-corrected scores in predicting
progression from aMCI to AD. Our experimental sample consisted of 270
aMCI patients who underwent extensive neurological and neuropsychological examinations
both at baseline and at the follow-up, conducted at least 3 years later.
At the follow-up 80 patients had converted to overt dementia. The predictive capacity
of raw, age-corrected, education-corrected and fully corrected scores on
RAVLT immediate and delayed recall was compared by examining the area under
the ROC curves (AUCs) of all of these scores to assess which (raw or corrected) scores achieves the
better reliability in predicting conversion to dementia. The condition (aMCI stable vs converted) was
analyzed to assess the odds ratios resulting from a logistic regression on the corrected and uncorrected
scores of RAVLT immediate and delayed recall. Even if both in immediate and in delayed recall
the ROCs of ‘raw scores’ were generally higher than the other ROCs on corrected scores, these
differences did not reach the level of statistical significance, failing to support the claim that unadjusted
test scores are superior to age- and education-corrected scores in predicting progression from
aMCI to AD.
Keywords: aMCI conversion, Alzheimer's Disease, age and education corrected scores, RAVLT memory test, raw scores,
uncorrected immediate and delayed recall.
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