A comparison of neuropsychological test performances between adults with mild cognitive impairment who progress to dementia and those who do not: A prospective longitudinal study

Alzheimer's disease (AD) is a progressive neurodegenerative condition marked by pronounced memory impairment. Mild Cognitive Impairment (MCI) is commonly viewed as a clinical condition between normal aging and AD in which individuals do not meet diagnostic criteria for probable AD, yet they experience memory loss that is significantly greater than expected for his/her age. Many researchers believe that MCI, particularly amnestic MCI may be a precursor to the development of probable AD. The characteristics of MCI have been in the forefront of numerous studies in hopes of identifying predictive factors that may contribute to the progression of MCI to AD. Longitudinal studies have examined the neuropsychological profiles of MCI patients in comparison to probable AD patients. However, studies have not yet examined the differences between MCI patients who actually progress to AD to those who do not. As part of an ongoing longitudinal study at UCLA, the present study compared the neuropsychological test profiles of amnestic MCI participants who progressed to probable AD ( N = 3) to those who did not (N = 9) across three annual evaluation periods, examining their performance in 5 cognitive domains (memory, language, visual-spatial, executive functioning, and attention/concentration). Though the original sample included 79 participants, only 12 completed three annual evaluations. Repeated-measures Analyses of Variance/Covariance (ANOVAs/ANCOVAs) found significance on 3 memory tests (CVLT List B, CVLT False Positives, and WMS-III Visual Reproduction 1), 3 language tests (Boston Naming Test with and without phonemic cues and COWA-Animals), 1 visual-spatial test (WAIS-III Block Design), and 2 executive functioning tests (WAIS-III Similarities and Stroop C). A binary logistic regression did not find a particular cognitive variable that better predicted MCI participants who would progress to AD. Exploratory analyses included an additional 16 participants with only two evaluation periods to augment the sample of 12 for a total of 23 MCI and 6 probable AD participants. Independent samples t-tests found significance on 5 memory tests and 1 language test. Findings are discussed, suggesting that serial neuropsychological assessments may hold promise for predicting MCI individuals who would progress to probable AD in order to offer early interventions.