Enhancing Cognitive Abilities with Comprehensive Training: A Large, Online, Randomized, Active-Controlled Trial

Abstract

Background: A variety of studies have demonstrated gains in cognitive ability following cognitive training interventions. However, other studies have not shown such gains, and questions remain regarding the efficacy of specific cognitive training interventions. Cognitive training research often involves programs made up of just one or a few exercises, targeting limited and specific cognitive endpoints. In addition, cognitive training studies typically involve small samples that may be insufficient for reliable measurement of change. Other studies have utilized training periods that were too short to generate reliable gains in cognitive performance.

Methods: The present study evaluated an online cognitive training program comprised of 49 exercises targeting a variety of cognitive capacities. The cognitive training program was compared to an active control condition in which participants completed crossword puzzles. All participants were recruited, trained, and tested online (N = 4,715 fully evaluable participants). Participants in both groups were instructed to complete one approximately 15-minute session at least 5 days per week for 10 weeks.

Results: Participants randomly assigned to the treatment group improved significantly more on the primary outcome measure, an aggregate measure of neuropsychological performance, than did the active control group (Cohen's d effect size = 0.255; 95% confidence interval = [0.198, 0.312]). Treatment participants showed greater improvements than controls on speed of processing, short-term memory, working memory, problem solving, and fluid reasoning assessments. Participants in the treatment group also showed greater improvements on self-reported measures of cognitive functioning, particularly on those items related to concentration compared to the control group (Cohen's d = 0.249; 95% confidence interval = [0.191, 0.306]).

Conclusion: Taken together, these results indicate that a varied training program composed of a number of tasks targeted to different cognitive functions can show transfer to a wide range of untrained measures of cognitive performance.

Trial registration: ClinicalTrials.gov NCT-02367898.

Trial registration: ClinicalTrials.gov NCT02367898.

Conflict of interest statement

Competing Interests: Lumos Labs, Inc. funded the research through the development of its software tools. JLH, DAS, KK, FF and MS are employed at Lumos Labs, the company that produces the cognitive training program Lumosity that is used in this study. These authors hold stock options in the company. RAN works as a consultant for Lumos Labs. MET is on the Scientific Advisory Board of Lumos Labs and holds stock options in the company. This does not alter the authors' adherence to PLOS ONE policies on sharing data and materials.

Figures

Fig 1. CONSORT flow chart of participants in the study.

Fig 2. Change in composite score (Grand Index) for the cognitive training treatment and crossword puzzle control conditions.

Error bars represent confidence intervals bootstrapped over 100,000 iterations. Mean change scores and error bars are based on unadjusted summary statistics. P value is based on results from the ANCOVA analysis described in Table 2. ***p

Fig 3. Change in individual assessments of cognitive ability.

Error bars represent confidence intervals bootstrapped over 100,000 iterations. Mean change scores and error bars are based on unadjusted summary statistics. P values are based on results from the ANCOVA analyses listed in Table 2. **p

Fig 4. Change in composite score (Grand Index) by number of active days in treatment and control conditions.

Lines represent estimates from the general linear model including effects of group, active day, and the group-by-active-days interaction. Shading represents 95% confidence intervals.