Remédiation cognitive de l’attention chez les patients atteints de maladie d’Alzheimer : un essai clinique randomisé

Abstract

Introduction

Alzheimer's disease (AD) affects approximately 200,000 individuals in Morocco, with projections indicating a doubling to 400,000 cases by 2050. The Rabat-Salé-Kénitra region accounts for nearly 22,000 patients, representing 11% of the national burden. Attentional deficits constitute one of the earliest and most debilitating cognitive manifestations of AD, progressively compromising patients’ functional autonomy and quality of life. Current pharmacological treatments (cholinesterase inhibitors, memantine) offer only modest symptomatic benefits, rarely exceeding 1.5 MMSE points at six months, while presenting significant side effects and costs exceeding 1100 dirhams monthly. This situation has prompted the development of non-pharmacological alternatives, particularly cognitive remediation therapy (CRT), which targets neuroplasticity mechanisms to restore or compensate for impaired cognitive functions. This study aimed to evaluate the effectiveness of a multimodal CRT program on attentional functions in patients with mild-to-moderate AD in the Rabat-Salé-Kénitra region.

Methods

This quasi-experimental study included 94 patients with probable AD diagnosed according to NINCDS-ADRDA criteria, with MMSE scores ≥ 12, aged ≥ 55 years. Participants were recruited from the Rabat Alzheimer Day Care Center, the geriatric psychiatry department of the Specialties Hospital, and home-based care settings. They were allocated to either a CRT group (n = 47) receiving 24 sessions of multimodal cognitive remediation over 12 weeks, or a control group (n = 47) receiving standard care. The CRT program incorporated five categories of attentional exercises: visual part-whole analysis, visuospatial transformations, eye-hand coordination tasks, visual analogies, and consecutive number searches. These tasks employed errorless learning, positive reinforcement, and metacognitive strategies to promote neuroplasticity. The control group continued receiving standard medical care, including regular geriatric or neurological consultations, maintenance of prescribed pharmacological treatments without dosage modifications, usual occupational activities, and informal caregiver support. Pre- and post-intervention assessments utilized the Bells Test (primary outcome), MMSE, and MoCA. Effect sizes were calculated using Cohen's d, and moderating variables (age, IADL, self-efficacy, motivation) were examined through correlation and stepwise regression analyses.

Results

The CRT group demonstrated exceptional improvements across all cognitive measures compared to the control group, which showed slight deterioration. On the Bells Test, the CRT group improved by 4.82 ± 2.09 bells versus a decline of -0.49 ± 0.98 in controls (Cohen's d = 3.26, P < 10^-10). The MMSE showed gains of 3.20 ± 1.10 points in the CRT group versus −0.75 ± 0.81 in controls (Cohen's d = 4.08, P < 10^-10). Similarly, MoCA scores improved by 3.21 ± 1.46 points versus −0.28 ± 0.98 in controls (Cohen's d = 2.81, P < 10^-10). These effect sizes substantially exceed those reported in international meta-analyses (typical SMD: 0.35-0.51). Robust correlations between attentional and global cognitive gains (r = 0.58–0.62, P < 0.001) support proximal transfer of benefits from attentional functions to general cognitive abilities. Subgroup analyses revealed differential efficacy according to patient characteristics. Patients younger than 75 years showed greater improvements across all measures (Bells Test: 5.34 vs. 4.11; MMSE: 3.67 vs. 2.53; MoCA: 3.89 vs. 2.31). The multiple regression model (R² = 0.67) identified instrumental autonomy (IADL, β = 0.40), age (β = −0.13), and self-efficacy (β = 0.60) as independent predictors of therapeutic response, confirming a triple interaction between functional reserve, neuronal reserve, and motivational factors.

Discussion and conclusion

This study establishes, for the first time in Morocco and the MENA region, the remarkable effectiveness of multimodal cognitive remediation on attentional functions in AD patients. The exceptional effect sizes suggest substantial neuroplastic reorganization of cognitive networks, exceeding typical procedural learning effects. The superiority of attentional gains on the Bells Test confirms the specific efficacy on visuospatial attention, a particularly vulnerable function in AD. The generalization of benefits to MMSE and MoCA scores demonstrates that attention serves as a supervisory cognitive domain facilitating the functioning of other systems through top-down control mechanisms. The favorable cost-effectiveness ratio of CRT makes it particularly relevant for healthcare systems with limited resources, offering a promising therapeutic alternative to pharmacological treatments. These findings support the systematic integration of culturally adapted CRT programs into regional care pathways and provide a reproducible model for investigating non-pharmacological interventions in diverse Arabic-speaking contexts. Future multicenter randomized trials with extended follow-up are warranted to confirm these results and document the long-term durability of therapeutic benefits.