Internal Consistency and Test-retest Reliability of the Visual Memory Associative Test TMA-93

Abstract Background: Memory tests focused on binding may be more sensitive to diagnose Alzheimer´s disease (AD) at an early phase. TMA-93 examines binding by pairs of drawings of semantically-related objects. Preliminary validation studies have confirmed good diagnostic accuracy for the test to discriminate between patients with cognitive impairment and healthy controls (HCs) in low-educated populations. This study aimed to evaluate the reliability (internal consistency and test-retest reliability) of the TMA-93ina clinic setting with a high proportion of individuals with low-educational attainment. Methods.-The study was undertaken in a memory clinic of a university hospital in Southern Spain. The internal consistency of the 10 items that compose the TMA-93 was estimated on a cross-sectional, case-control study. 35 patients with amnestic Mild Cognitive Impairment and 40 healthy controls (HCs) matched by age, gender, and educational attainment were tested by the TMA-93. The participant’s performance on each of the 10 items was scored from 0 to 3, according to the instructions for the test (maximum total score= 30 points). The internal consistency was estimated by Cronbach’s alpha. In addition, “split-half reliability”, by Spearman-Brown coefficient;“corrected item-total correlations”, and item redundancy, by “Cronbach’s alpha if item deleted”, were analyzed. The test-retest reliability for the TMA-93 total score was studied in 51HCstested by the same examiner 2-4 months apart and quantified by the intraclass correlation coefficient (ICC). Results.-Internal consistency was “optimal” (Cronbach’s alpha=0.936). Split-half reliability was also high (Spearman-Brown coefficient= 0.911). The item-total score correlations were always above 0.660. No item was redundant as Cronbach’s alpha did not increase at deleting anyone. Test-retest reliability was “good” [ICC=0.802 (CI 95%=0.653-0.887)].Conclusion.-The internal consistency and test-retest reliability of the TMA-93 are “good”. In addition to other psychometric properties, these results support the test for examining memory binding,particularly in contexts of low-educational attainment.