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. 2018;64(1):195-204.
doi: 10.3233/JAD-180229.

Using Neuropsychological Process Scores to Identify Subtle Cognitive Decline and Predict Progression to Mild Cognitive Impairment

Kelsey R Thomas  1   2 , Emily C Edmonds  1   2 , Joel Eppig  3 , David P Salmon  4 , Mark W Bondi  1   2 ; Alzheimer’s Disease Neuroimaging Initiative
Affiliations

Using Neuropsychological Process Scores to Identify Subtle Cognitive Decline and Predict Progression to Mild Cognitive Impairment

Kelsey R Thomas et al. J Alzheimers Dis. 2018.

Abstract

Background: We previously operationally-defined subtle cognitive decline (SCD) in preclinical Alzheimer's disease (AD) using total scores on neuropsychological (NP) tests. NP process scores (i.e., provide information about how a total NP score was achieved) may be a useful tool for identifying early cognitive inefficiencies prior to objective impairment seen in mild cognitive impairment (MCI) and dementia.

Objective: We aimed to integrate process scores into the SCD definition to identify stages of SCD and improve early detection of those at risk for decline.

Methods: Cognitively "normal" participants from the Alzheimer's Disease Neuroimaging Initiative were classified as "early" SCD (E-SCD; >1 SD below norm-adjusted mean on 2 process scores or on 1 process score plus 1 NP total score), "late" SCD (L-SCD; existing SCD criteria of >1 SD below norm-adjusted mean on 2 NP total scores in different domains), or "no SCD" (NC). Process scores considered in the SCD criteria were word-list intrusion errors, retroactive interference, and learning slope. Cerebrospinal fluid AD biomarkers were used to examine pathologic burden across groups.

Results: E-SCD and L-SCD progressed to MCI 2.5-3.4 times faster than the NC group. Survival curves for E-SCD and L-SCD converged at 7-8 years after baseline. The combined (E-SCD+L-SCD) group had improved sensitivity to detect progression to MCI relative to L-SCD only. AD biomarker positivity increased across NC, SCD, and MCI groups.

Conclusions: Process scores can be integrated into the SCD criteria to allow for increased sensitivity and earlier identification of cognitively normal older adults at risk for decline prior to frank impairment on NP total scores.

Keywords: Alzheimer’s disease; dementia; early detection; mild cognitive impairment; neuropsychology; subtle cognitive decline.

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Conflict of interest statement

Conflict of Interest/Disclosure Statement

M.W.B. is paid royalties from Oxford University Press and serves as a consultant for Eisai and Novartis. D.P.S. serves as a consultant for CHDI Foundation, Novartis, and Bristol-Meyers Squibb. The other authors report no disclosures.

Figures

Figure 1.
Figure 1.
Existing criteria for SCD and MCI, and proposed SCD staging criteria. Impaired neuropsychological total and process scores were defined as >1 SD below age/education/sex-adjusted mean. FAQ=Functional Activities Questionnaire
Figure 2.
Figure 2.
Kaplan Meier curves for NC, E-SCD, and L-SCD progression to MCI over a) 5 years and b) 10 years.
Figure 3.
Figure 3.
Kaplan Meier curves for NC, E-SCD, L-SCD, and MCI progression to dementia over a) 5 years and b) 10 years.
Figure 4.
Figure 4.
Proportion of participants with positive AD biomarkers by cognitive group. Sample size by group was: NC n=350, E-SCD n=104, L-SCD n=78, MCI n=434. Letters denote group differences (p<.05): a=significant different than NC, b=significant different than E-SCD, c=significant different than L-SCD, d=significant different than MCI.
See this image and copyright information in PMC

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