Beyond Uniform Impairment: Investigating Declarative Memory Profiles in Nonspecific Mild Intellectual Disability Using Latent Profile Analysis.

Background: Significant memory impairments are consistently observed in individuals with intellectual disabilities (ID), but considerable variability exists. This study investigated the heterogeneity of declarative memory in children and adolescents with nonspecific mild intellectual disability (NSID) to identify distinct memory profiles and potential predictors of this disability.

Methods: A latent profile analysis (LPA) was conducted on a large sample (N = 999, including 114 with NSID) using six supplementary memory indices from the Test of Memory and Learning-Second Edition (TOMAL-2). A logistic regression analysis subsequently examined the predictive power of TOMAL-2 indices for NSID diagnosis.

Results: LPA revealed two distinct memory profiles: a 'memory impaired group' (24% of the total sample) with below-average scores across all indices and a 'high-performers group' (76%) with consistently above-average scores. Individuals with NSID were significantly more likely to belong to the 'memory impaired group'. Logistic regression analysis revealed that lower scores on the Attention/Concentration Index, Sequential Memory Index and Verbal Delayed Recall Index were the strongest predictors of NSID. However, notably, 25% of individuals with mild NSID were classified in the 'high performers group', exhibiting typical or above-average memory scores across multiple indices.

Conclusions: This study demonstrates significant heterogeneity in declarative memory among individuals with NSID, challenging the assumption of uniform impairment. The identified memory profiles and predictive indices offer valuable insights for more precise diagnostic assessment and the development of tailored interventions. Further research should investigate the factors contributing to this variability and explore the potential of these findings for improved support and educational strategies.

Trial Registration: NCT06215092.