Investigation of a Model-Based Working Memory Training With and Without Distractor Inhibition and Its Comparative Efficacy: A Randomized Controlled Trial on Healthy Old Adults

Background; : Various working memory (WM) trainings have been tested, but differences in experimental designs, the lack of theoretical background, and the need of identifying task-related processes such as filtering efficiency limit conclusions about their comparative efficacy.; Objectives; : In this study, we compared the efficacy of a model-based WM training with (MB; +; ) and without (MB) distractor inhibition on improving WM capacity to a dual; n-back; and active control condition.; Methods; : This randomized clinical trial included 123 healthy elderly adults (78 women, 45 men; aged 64.1 ± 8.3 years). All groups underwent 12 40-min training sessions over 3 weeks and four cognitive testing sessions. The first two sessions served as double baseline to account for practice effects. Primary outcome was WM capacity post-training measured by complex span tasks. Near and far transfer was assessed by simple span, n-back, visuospatial and verbal learning, processing speed, and reasoning tasks.; Results; : Due to preliminary termination (COVID-19), 93 subjects completed the post-training and 60 subjects the follow-up session. On a whole group level, practice effects occurred from prebaseline to baseline in WM capacity (; b; = 4.85,; t; (103); = 4.01,; p; < 0.001,; r; = 0.37). Linear mixed-effects models revealed a difference in WM capacity post-training between MB; +; and MB (; b; = -9.62,; t; (82); = -2.52,; p; = 0.014,; r; = 0.27) and a trend difference between MB; +; and dual; n-back; (; b; = -7.59,; t; (82); = -1.87,; p; = 0.065,; r; = 0.20) and control training (; b; = -7.08,; t; (82); = -1.86,; p; = 0.067,; r; = 0.20). Univariate analyses showed an increase between pre- and post-training for WM capacity within MB; +; (; t; (22); = -3.34,; p; < 0.05) only. There was no difference between groups pre- and post-training regarding near and far transfer. Univariate analyses showed improved visuospatial learning within MB; +; (; t; (21); = -3.8,; p; < 0.05), improved processing speed (; t; (23); = 2.19,; p; < 0.05) and; n; -back performance (; t; (23); = 2.12,; p; < 0.05) in MB, and improved; n; -back performance (; t; (25); = 3.83,; p; < 0.001) in the dual; n; -back training.; Interpretation; : A model-based WM training including filtering efficacy may be a promising approach to increase WM capacity and needs further investigation in randomized controlled studies.