The differential contribution of immediate memory and executive functions in age‐related neurocognitive disorders

Abstract

Background Comprehensive neuropsychological assessment (NPA) has proven to be a diagnostic and monitoring procedure that contributes to the understanding of neurocognitive disorders (NCDs). Despite memory deficits being considered as hallmarks of age‐related cognitive decline, executive impairment has emerged as the strongest correlate of functional dependence that characterizes major NCD. Hence, the present study aims to: (1) examine the neuropsychological predictors of major NCD; (2) compare between indices of immediate memory and executive functions involved in cognitive decline. Method Out of a dataset of 179 (Mage = 75±5.43; women = 96) elderly outpatients, 97 individuals (Mage = 76±5.72; women = 51) met the DSM‐5 criteria for NCD as they presented impairment in at least one cognitive domain and, in the case of major NCD, impact on activities of daily living. The sample underwent NPA consisting of a two‐screening procedure; ten domain‐specific tests; psychodiagnostic‐functional evaluation. Analyses relied on multivariate and non‐parametric tests to examine differential clinical profiles and NPA tools, respectively. Result A prior analysis using the Hosmer‐Lemeshow test confirmed the goodness of the model (χ2 = ‐4,771; p = .782) (diagnostic labels: major vs. mild NCDs). The final model obtained could correctly predict 71% of cases. Logistic regression through backward elimination revealed that the lower the scores at Frontal Assessment Battery (FAB), the greater the chances of fitting major NCD (vs. mild NCD) (B = ‐.284; p = .006). Friedman test enabled multiple comparisons within the whole sample, and by considering mild and major groups separately, with respect to immediate memory (FCSRT‐ISC and Babcock Story‐IR) and executive indices (Clock Drawing Test and Digit Span Backwards). The analyses showed a significant difference between the ranks of test scores only within the major NCD group through Bonferroni correction (χ2 = 8.813, p = .032), revealing a greater drop in Clock Drawing Test than in Babcock Story‐IR (χ2 = ‐.906, p = .030). Conclusion These preliminary findings point to the importance of considering, besides memory indices, executive performances in elderly patients affected by severe cognitive‐functional impairment, consistent with potential implications of planning difficulties in the progressive loss of everyday life autonomy. Screening for executive functioning may also enhance the understanding about the clinical course from mild to severe disease, thus orienting clinicians in the differential diagnosis, secondary prevention, and treatment of NCDs.