Persistent Failure to Recover from Proactive Semantic Interference on the Cognitive Stress Test Differentiates Between Amnestic Mild Cognitive Impairment, Pre-Mild Cognitive Impairment, and Cognitively Unimpaired Older Adults
Affiliations: Center for Cognitive Neuroscience and Aging and Department of Psychiatry and Behavioral Sciences, Miller School of Medicine, University of Miami, Miami, FL, USA
Correspondence:
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Correspondence to: David A. Loewenstein, PhD, ABPP-CN, Director, Center for Cognitive Neuroscience and Aging, Professor of Psychiatry and Behavioral Sciences, Professor of Neurology, University of Miami, 1695 NW 9th Ave, Suite 3202, Miami, FL 33136, USA. Tel.: +1 305 355 7016; Fax: +1 305 255 9076; E-mail: dloewenstein@med.miami.edu.
Abstract: Background:Susceptibility to proactive semantic interference (PSI) and the inability to ameliorate these difficulties with one additional learning trial have repeatedly been implicated as early features of incipient Alzheimer’s disease (AD). Unfortunately, persistent failure to recover from PSI (frPSI) after repeated learning trials, are not captured by existing memory measures, or been examined in pre-mild cognitive impairment (PreMCI). Objective:A novel Cognitive Stress Test (CST) was employed to measure the impact of PSI, initial failure to recover from PSI and persistent effects of PSI, despite multiple learning trials of the new to-be-remembered material (pfrPSI). We hypothesized that PSI deficits on the CST would persist in both PreMCI and amnestic MCI (aMCI) groups over repeated learning trials when compared to cognitively unimpaired (CU) older adults. Methods:One hundred fifty older adults (69 CU, 31 PreMCI, and 50 aMCI) underwent a standardized clinical and neuropsychological evaluation. The CST was independent of diagnostic classification. Results:Even after adjusting for strength of initial learning, aMCI and PreMCI groups demonstrated greater persistent PSI (pfrPSI) relative to the CU group despite repeated learning trials of List B. Further, the aMCI group made a higher number of semantic intrusion errors relative to the PreMCI and CU groups on all List B Cued Recall trials. Conclusion:Persistent PSI appears to be a common feature of aMCI and PreMCI. The possible theoretical mechanisms and empirical implications of these new findings are discussed.
