Effects of Delay Duration on the WMS Logical Memory Performance of Older Adults with Probable Alzheimer's Disease, Probable Vascular Dementia, and Normal Cognition

Archives of Clinical Neuropsychology 32 (2017) 375–380 Effects of Delay Duration on the WMS Logical Memory Performance of Older Adults with Probable Alzheimer’s Disease, Probable Vascular Dementia, and Normal Cognition Valencia Montgomery*, Katie Harris, Anthony Stabler, Lisa H. Lu Roosevelt University, Department of Psychology, Chicago, IL 60603, USA *Corresponding author at: Roosevelt University, Department of Psychology, 18 South Michigan Avenue, Chicago, IL 60603, USA. Tel.: +1-312-330-8563; fax: +1-312-341-6362. E-mail address: (V. Montgomery). Editorial Decision 4 January 2017; Accepted 16 January 2017 Abstract Objective: To examine how the duration of time delay between Wechsler Memory Scale (WMS) Logical Memory I and Logical Memory II (LM) affected participants’ recall performance. Method: There are 46,146 total Logical Memory administrations to participants diagnosed with either Alzheimer’s disease (AD), vascular dementia (VaD), or normal cognition in the National Alzheimer’s Disease Coordinating Center’s Uniform Data Set. Results: Only 50% of the sample was administered the standard 20–35 min of delay as specified by WMS-R and WMS-III. We found a significant effect of delay time duration on proportion of information retained for the VaD group compared to its control group, which remained after adding LMI raw score as a covariate. There was poorer retention of information with longer delay for this group. This association was not as strong for the AD and cognitively normal groups. A 24.5-min delay was most optimal for differentiating AD from VaD participants (47.7% classification accuracy), an 18.5-min delay was most optimal for differentiating AD versus normal participants (51.7% classification accuracy), and a 22.5-min delay was most optimal for differentiating VaD versus normal participants (52.9% classification accuracy). Conclusions: Considering diagnostic implications, our findings suggest that test administration should incorporate precise tracking of delay periods. We recommend a 20-min delay with 18–25-min range. Poor classification accuracy based on LM data alone is a reminder that story memory performance is only one piece of data that contributes to complex clinical decisions. However, strict adherence to the recommended range yields optimal data for diagnostic decisions. Keywords: Sensitivity; Specificity; Non-standard test administration; Training Introduction Consistency in the administration of neuropsychological tests is critical to obtaining valid and reliable findings. The results of these tests provide specific information about individuals’ strengths, weaknesses and the nature of their cognitive deficits. Any deviation from standard test administration may present problems in the reliability and validity of the test results (Lee, Reynolds, & Willson, 2008), which can present potentially significant problems given the role of these measures in contributing to differential diagnoses and treatment recommendations. There is a paucity of research evaluating the effects of nonstandard administrations on patients’ performances. Test administration errors occur in the provision of instruction, presentation of test items, and in the scoring of measures. The speed, time, and type of presentation may affect the performance on neuropsychological tests. For example, speeded or slowed presentation of stimuli on tests such as Digit Span have been found to significantly affect performance (Baddeley & Lewis, 1984; Hagen, Durham, & Shannon, 1977). Baddeley and Lewis (1984) found that individuals recalled more digits during Digit Span with rapid presentation if retrieval occurs within 1–2 s following presentation. Hagen and colleagues (1977) © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: . doi:10.1093/arclin/acx005 Advance Access publication on 3 February 2017 376 V. Montgomery et al. / Archives of Clinical Neuropsychology 32 (2017); 375–380 found better performances on Digit Span when voice inflection is dropped on the last digit. Shum, Murray and Eadie (1997) assessed the affect of speed of story memory presentation on performance by evaluating differences in participant performance on the Wechsler Memory Scale-Revised (WMS-R) Logical Memory at three speeds (slow, medium, and fast). The researchers found clinically and statistically significant differences in test scores when the story was presented at the slow speed versus the other speeds. More explicit instructions and verbalization during problem solving seem to correlate with improved performance on measures such as WAIS Digit Symbol and Wisconsin Card Sorting Test (Dillon, 1981; Joncas & Standing, 1998; Perry, Potterat, & Braff, 2001). Therefore, across various neuropsychological tests, deviations in standard administration can have a significant affect on test scores. However, some deviations do not seem to affect performance. For example, performance was not significantly affected by variations in delay periods (i.e., 15, 30, 45, and 60 min) on the Rey-Osterrieth Complex Figure (Berry & Carpenter, 1992). The WMS is one of the most frequently utilized tests amongst neuropsychologists in the United States (Rabin, Barr, & Burton, 2005). In fact, a brief search of “Logical Memory” in Google Scholar provides a return of 15,000+ articles in the last 5 years alone. The assessment of memory functioning, often using measures such as the WMS that incorporate a delay paradigm, is an integral component of the evaluation of cognitive deficits and decline in patients. Weintraub et al. (2009) found no significant differences in the affect of delay interval on number of WMS Logical Memory units recalled in a population of cognitively normal participants; however, cognitively impaired participants were not included in the sample. Given that standardized administration is assumed when interpreting neuropsychological data, the current study aims to examine the extent to which older adults (>65 years) were administered the WMS Logical Memory Delayed subtest (LMII) within the standard 20- to 35-min delay used in this data set. Additionally, this study aims to examine the degree to which the delay duration affected proportion of information retained across the delay. Methods For the current study, we obtained archival data from the National Alzheimer’s Coordinating Center’s (NACC) Uniform Data Set (UDS; Weintraub et al., 2009). Between 2005 and 2014, each participant within the UDS underwent a standardized neurodiagnostic evaluation and received a consensus diagnosis from trained clinicians. The WMS-R and WMS-III Logical Memory Immediate (LMI) and Delayed (LMII) subtests (Harcourt Assessment, Inc., 1987) were administered to 21,376 participants with either probable Alzheimer’s disease (AD), probable vascular dementia (VaD), or normal cognition at an initial evaluation, with a total of 46,146 Logical Memory administrations after accounting for follow-up evaluations. A (...truncated)