Ikos Test: New Tool for the Assessment of Semantic Knowledge in Early Alzheimer Disease

Article type: Research Article

Authors: Cejudo, Juan Carlos^{a; *} | Samaniego, Melissa^a | Almeria, Marta^{b; c} | Castrillo, Susana^d | Medina, Lidia^e | Gil, Domènec^a

Affiliations: [a] Cognitive Impairment and Dementia Unit, Hospital Sagrat Cor, Hermanas Hospitalarias, Martorell, (Barcelona), Spain | [b] Cognition and Behavior Unit, Department of Neurology, Hospital Universitari Mútua Terrassa, Terrassa (Barcelona), Spain | [c] Department of Medicine, Autonomous University of Barcelona, Barcelona, Spain | [d] RGG Sant Roc (DGPS), Drets Socials Departament, Generalitat de Catalunya, Barcelona, Spain | [e] Cognitive Impairment and Dementia Unit, Hospital Atenció Intermedia Mutuam Güell, EAPS Mutuam Barcelona, Barcelona, Spain

Correspondence: [*] Correspondence to: Juan Carlos Cejudo, Cognitive Impairment and Dementia Unit, Hospital Sagrat Cor. Hermanas Hospitalarias, Avda Comte de Llobregat, 117, CP 08760, Martorell, Barcelona, Spain. Tel.: +34937769991; Fax: +34937750320; Email: [email protected].

Abstract: Background:Semantic memory (SM) constitutes a cognitive system that is seriously affected by Alzheimer’s disease (AD). There are several tests for assessing SM, but a tool is needed to assess AD in the early stages of the illness. Objective:The study aimed to create, validate, and normalize a new test to assess SM, called the Ikos test, for AD and early AD in clinical practice. Methods:62 healthy adults as a control group (CG), 62 AD, and 60 amnestic mild cognitive impairment (aMCI) subdivided into a group that progresses to AD, and another group that does not progress to AD were selected. The internal consistency (IC), the construct validity (CV), and reliability between raters and the test-retest were analyzed. We used the Bayesian approach to establish the accuracy of the diagnosis of the Ikos test in AD and early AD. Results:IC showed a Kuder-Richardson index of r = 0.945. The CV between the Ikos test and Pyramids and Palm Trees; Intraclass Correlation Coefficient (ICC) index was 0.897. The Kappa index was between 0.865 and 0.912, and the ICC index was 0.873 for the test-retest reliability. The Area Under the Curve was 0.981, sensitivity (SE) was 0.95, and specificity (SP) was 0.96 in AD/CG. In contrast, in the MCI-AD/CG group, SE = 0.77 and SP = 0.80. Conclusion:The Ikos test accomplishes the criteria of validity and reliability with high correlation indexes. Therefore, it can be considered a valid, reliable, and easily applicable tool for SM assessment in diagnosing AD and the early stages of clinical disease.

Keywords: Early Alzheimer’s disease, neuropsychology of memory, semantic knowledge, semantic knowledge in dementia, semantic memory test

DOI: 10.3233/JAD-220516

Journal: Journal of Alzheimer's Disease, vol. 90, no. 1, pp. 151-160, 2022