Title : Discriminative power of a reaction-time test in the evaluation of cognitive impairment in elderly with high educational disparity
Abstract:
Objective: We aimed to analyze the discriminative power of a culture-free Go/No-Go task by comparing three groups: cognitively unimpaired healthy elderly, Mild Cognitive Impaired subjects (MCI), and early Alzheimer´s disease patients (AD). For the three groups the samples had high educational disparity.
Methods: One hundred and ten participants with a wide range of years of formal education (0–14 years) were randomly selected from a geriatric unit and divided based on their CDR scores into cognitively unimpaired (CDR = 0), MCI (CDR = 0.5), and early AD (CDR = 1). All the participants underwent a 90-second Go/No-go task which consisted of 72 (80%) targets and 18 (20%) non-targets. For each participant, reaction times and intraindividual variability of reaction times of all correct target responses, as well as the number of omission and commission errors were evaluated. For each participant, the coefficient of variability was also calculated by dividing the standard deviation of the reaction times by the correspondent mean reaction time. A MANCOVA was performed to examine between-group differences using educational level, age, and sex as covariates. Discriminate analysis was performed to find the most reliable test-variable to discriminate the three groups.
Results: Mean group differences reached significance for commission errors, intraindividual variability of reaction time, and coefficient of variability. The discriminant analysis demonstrated that coefficient of variability was the most reliable variable to predict the CDR scores.
Conclusion: The Go/No-Go task was able to discriminate people with MCI or early AD from controls independent of the educational level of the participants.
Audience Takeaway:
- This study provides a practical solution (reaction-time test) to the problem of distinguishing MCI and early AD from healthy elderly.
- The test can be applied in different cultures.
- The test is easy to administer.
- There is no effect of fatigue (the test is quick).
- There is no learning effect and the test can be used many times in order to measure treatment’s efficacy.
- The solution is affordable because the software is free.
