Study design and patient population
This was a single-center, randomized prospective study, conducted in the Multiple Sclerosis Center, Sheba Medical Center, Tel Hashomer, Israel. Ethical approval to conduct the study was granted by the Sheba Medical Center Ethics Committee (Institutional Review Board number SMC-333016), and each participant signed written informed consent. Data were collected between May 2016 and February 2021. Data is available upon request from the authors of this study.
Inclusion criteria were as follows: (1) Patients diagnosed with relapsing-remitting multiple sclerosis or secondary-progressive multiple sclerosis according to revised McDonald Criteria 2010 (24). (2) Age between 18-55 years. (3) Mild cognitive impairment, defined as a cognitive test performance in information processing speed or executive function of a score < 95. (4) Current treatment with Rebif® and RebiSmart 2.0 (in doses of 22 or 44 mcg subcutaneous, three times a week) (5) Signed written informed consent.
Exclusion criteria were as follows: (1) Steroid treatment within the last 3 months. (2) Severe cognitive decline that prevents cognitive assessment. (3) Significant depression and/or anxiety. (4) Visual impairment or upper extremity motor disability the precludes the ability to perform cognitive training. Demographic and clinical data were collected for all of the study subjects and included age, gender, years of education, disease duration, and disability status as measured by the Expanded Disability Status Scale (EDSS) (25).
Cognitive assessments
Cognitive assessment was performed using the computerized MindStreams Global Assessment Battery (NeuroTrax Corp., Bellaire, TX, USA), which has been validated in MS population (2), and was reported to have good reliability and validity relative to paper-based tests (9). Executive function and information processing speed domains were evaluated, as they reflect the most vulnerable cognitive impairments in MS patients. Outcome parameters accuracy and response time were normalized for age and education according to stratifications of a normative database of cognitively healthy subjects to fit an IQ-like scale (mean: 100, SD: 15). Value of 95 was defined as the cutoff for mild cognitive impairment in either executive function or information processing speed domains.
Randomization
Patients eligible for the study signed written informed consent and were randomized to either the game training or the non-game training group. Randomization was performed for cognitive performance and EDSS which were the major important variables to ensure similar cognitive performance and disease characteristics before cognitive game practice.
Sample size calculation
A sample size calculation demonstrated that a sample of 42 subjects in each group will yield 80% power to detect a difference in means of 5.000 (the difference between a Group 1 mean, m1, of 0.0 and a Group 2 mean, m2, of -5.0) assuming that the common standard deviation is 8 using a two-group t-test with a 0.050 two-sided significance level.
The expected drop-out rate in this study was 20%, hence, we aimed to enroll 48 subjects in each group.
Cognitive neuro-game training
Cognitive neuro-game training using HappyNeuron platform (HN, https://www.happyneuronpro.com/en) was performed by the patients randomized into the training group twice weekly, each session lasting 30 minutes, for 6 months. HappyNeuron platform is a web-based cognitive training game platform. Nine cognitive exercises developed by Happyneuron for cognitive training were applied for practice during this study. The HAPPYneuron brain training cognitive game-platform is aimed to stimulate various cognitive aspects including memory, attention, language, executive functions (reasoning, logical thinking), and visual and spatial skills. Specifically, we included nine cognitive games related to executive functions, e.g., Turn around, Points of View, Basketball in New York, Sleight of Hands, Towers of Hanoi, and information processing speed, e.g., Sleights of hands, Entangled Figures, Towers of Hanoi, Under Pressure, Shapes and Colors, Private Eye Turn around, Points of View. A detailed description of each game can be found in Appendix Table 1. For the purpose of the current study, we have defined the same level of difficulty for each game to all participants. Each patient was asked to complete all nine cognitive games in the same order using the computer keyboard. For each cognitive game, average accuracy and response time were recorded.
Game training adherence assessment
The adherence rate in the game training group was assessed weekly using the HN platform to ensure patients keep training twice weekly for 30 minutes’ sessions. Subjects that missed more than 20% of the training sessions over time were excluded from the analysis
Statistical Analysis
All measured variables and derived parameters were tabulated by descriptive statistics. Paired T-test (paired observations) was applied for testing the statistical significance of the change in the executive function and in information processing speed from baseline at month 3 and month 6 within each study group.
The two-sample T-test was applied to compare the relative change in executive function and information processing speed from baseline between Training and Non-Training groups at month 3 and month 6.
A linear model for repeated measures was applied for analyzing the difference between Training and Non-Training groups in executive function change and in information processing speed change from baseline at any time, including the fixed effect time and adjusted for baseline.
Chi-Square Test was applied to compare the frequency of improvement in executive function and in information processing speed between Training and Non-Training groups at month 3 and month 6.
The data were analyzed using the SAS ® version 9.4 (SAS Institute, Cary North Carolina).