Declarative Memory Profiles in Children with Non-Specific Intellectual Disability: A Cluster Analysis Approach

Urszula Sajewicz-Radtke ¹ Ariadna Beata Łada-Maśko ² Michał Olech ³ Krzysztof Leoniak ⁴ Bartosz M. Radtke ^1*

• ¹ Laboratory of Psychological and Educational Tests, Gdansk, Poland
• ² Institute of Psychology, Faculty of Social Sciences, University of Gdańsk, Gdansk, Pomeranian Voivodeship, Poland
• ³ Department of Psychology, Medical University of Gdansk, Gdańsk, Pomeranian, Poland
• ⁴ Departament of Social Psychology, Institute of Psychology, Faculty of Pedagogy and Psychology, Maria Curie-Skłodowska University, Lublin, Poland

Introduction: Intellectual disability (ID) is increasingly being understood as a multidimensional condition that requires assessment beyond general intelligence. While traditional approaches focus on IQ), memory impairment plays a critical role in learning and adaptation. This study explored the declarative memory profiles of individuals diagnosed with nonspecific intellectual disability (NSID) to identify cognitive patterns that may inform intervention strategies.The study included 114 individuals (56 girls and 58 boys) aged 10-17 years with a confirmed mild NSID diagnosis. The participants underwent a comprehensive declarative memory assessment using the Polish version of the Test of Memory and Learning, Second Edition (TOMAL-2). A subset of 68 participants was assessed using the Stanford-Binet Intelligence Scales, Fifth Edition (SB5). Cluster analyses were performed to identify memory profiles based on the TOMAL-2 indices and their relationships with intelligence measures.Results: Two distinct memory profiles were identified. Cluster 1 (53% of the sample) exhibited lower scores across all memory indices, particularly for free recall, associative recall, and learning efficiency. Cluster 2 (47%) demonstrated relatively preserved memory abilities. Further analysis incorporating IQ measures showed that nonverbal intelligence was more strongly associated with memory performance than verbal intelligence. Notably, learning efficiency, rather than delayed verbal recall, was the strongest differentiator between the clusters.Conclusions: These findings highlight the heterogeneity of memory abilities in NSID, emphasizing the need for cognitive profiling beyond IQ. Learning potential may be a more predictive factor of functional outcomes, warranting further research and targeted interventions to enhance the adaptive capabilities in this population.