Increasing Working Memory in Young Healthy Adults: a Cluster Randomized Controlled Trial of a Multifaceted Brain Training Intervention

A cluster randomized controlled trial enrolled 2389 healthy students with the objective to test the effectiveness of a commercially developed multifaceted brain training intervention. Students were recruited from 17 Danish upper secondary education schools and were enrolled in one of three conditions: (1) multifaceted brain training intervention (MBT), (2) active control assigned to dual-n-back combined with light physical activity (AC), and (3) passive control (PC). Randomization was completed at class level, and number of classes was 99. The training volume was matched between the two active groups of the study and amounted to 1 h per week for 12 weeks. Hierarchical mixed regression models were used to analyze the data. No significant effects of MBT were found on the primary outcome measures of visual and verbal working memory. On secondary outcome measures including sustained attention, well-being, mindset, and sleep quality, no significant effects were observed. Supplementary, sensitivity analyses including only the classes, where the implementation was deemed successful, were conducted, revealing a single significant finding in relation to sleep quality, but not leading to a change in the overall results. Planned subgroup analysis did not show convincing differential effects of students with high versus low intelligence, with or without ADHD, growth mindset versus fixed mindset.