Tablet-Based Assessment of Picture Naming in Prodromal Alzheimer's Disease: An Accessible and Effective Tool for Distinguishing Mild Cognitive Impairment from Normal Aging

Abstract

Introduction: Effective mild cognitive impairment (MCI) screening requires accessible testing. This study compared two tests for distinguishing MCI patients from controls: rapid automatized naming (RAN) for naming speed and low-contrast letter acuity (LCLA) for sensitivity to low-contrast letters.

Methods: Two RAN tasks were used: the Mobile Universal Lexicon Evaluation System (MULES, picture naming) and the Staggered Uneven Number test (SUN, number naming). Both RAN tasks were administered on a tablet and in a paper/pencil format. The tablet format was administered using the Mobile Integrated Cognitive Kit application. LCLA was tested at 2.5% and 1.25% contrast.

Results: Sixty-four participants (31 MCI, 34 controls; mean age 73.2 ± 6.8 years) were included. MCI patients were slower than controls for paper/pencil (75.0 vs. 53.6 s, p < 0.001), and tablet MULES (69.0 s vs. 50.2 s, p = 0.01). The paper/pencil SUN showed no significant difference (MCI: 59.5 s vs. controls: 59.9 s, p = 0.07) nor did the tablet SUN (MCI: 59.3 s vs. controls: 55.7 s, p = 0.36). MCI patients had worse performance on LCLA testing at 2.5% contrast (33 letters vs. 36, p = 0.04*) and 1.25% (0 letters vs. 14 letters, p < 0.001). Receiver operating characteristic (ROC) analysis showed similar performance of paper/pencil and tablet MULES in distinguishing MCI from controls (area under the ROC curve [AUC] = 0.77), outperforming both SUN (AUC = 0.63 paper, 0.59 tablet) and LCLA (2.5% contrast: AUC = 0.65, 1.25% contrast: AUC = 0.72).

Conclusion: The MULES, in both formats, may be a valuable screening tool for MCI.

Keywords: Aging and cognition; Alzheimer’s dementia; Assessment measures; Cognitive aging; Cognitive impairment; Cognitive screening test; Contrast sensitivity; Digital assessment; Mild cognitive impairment; Rapid automatized naming task; Visual acuity.

Fig. 1.

Binocular visual tests. a The Mobile Universal Lexicon Evaluation System (MULES) is a rapid picture-naming test (MULES test © New York University, text and photographs, registration number: TXu002026665; all rights reserved). It consists of a double-sided, laminated 8.5 × 11-inch sheet featuring 54 color photographs of fruits, objects, and animals in context. b The Staggered Uneven Number (SUN) test is a novel rapid number-naming task (SUN test © 2019 New York University; all rights reserved). It is a single-sided 8.5 × 11-inch sheet with 145 single- and double-digit numbers arranged in zigzag or horizontal patterns with varying spacing. Participants are instructed to read aloud each picture or number as quickly and accurately as possible, starting from the top left row and continuing across all subsequent rows. c LCLA chart is a specialized tool used to assess the ability to see details under conditions of reduced contrast, which can reveal visual impairments that are not detected by standard high contrast charts. Unlike conventional charts that use high-contrast letters (like those on the Snellen chart), low-contrast charts use letters, numbers, or symbols that are in shades of gray and have less contrast with their background, making them more challenging to identify.

Fig. 2.

Paper/pencil and tablet MULES performance between groups. A box and whisker plot displays the distribution of a dataset by showing the median, quartiles, and range. The box represents the interquartile range (IQR) between the 25th percentile (Q1) and the 75th percentile (Q3), with the median marked inside the box. Whiskers extend to 1.5 times the IQR from the quartiles, illustrating the spread of the data. Outliers beyond the whiskers are plotted as individual points, highlighting values that fall outside the typical range.

Fig. 3.

Discriminatory capacity: area under curve analyses. Area under the ROC curve (AUC) plots are displayed for LCLA tests, paper/pencil MULES and SUN tests, and tablet MULES and SUN tests. Each curve represents the tradeoff between sensitivity and specificity at different cutoffs. The AUC values are provided for each test.

Fig. 4.

Paper/pencil and tablet sun performance between groups. A box and whisker plot displays the distribution of a dataset by showing the median, quartiles, and range. The box represents the interquartile range (IQR) between the 25th percentile (Q1) and the 75th percentile (Q3), with the median marked inside the box. Whiskers extend to 1.5 times the IQR from the quartiles, illustrating the spread of the data. Outliers beyond the whiskers are plotted as individual points, highlighting values that fall outside the typical range.

Fig. 5.

LCLA at 2.5% and 1.25% contrast between groups. A box and whisker plot displays the distribution of a dataset by showing the median, quartiles, and range. The box represents the interquartile range (IQR) between the 25th percentile (Q1) and the 75th percentile (Q3), with the median marked inside the box and labeled. Whiskers extend to 1.5 times the IQR from the quartiles, illustrating the spread of the data. Outliers beyond the whiskers are plotted as individual points, highlighting values that fall outside the typical range.