Researchers pooled randomized controlled trials of programs that train a thinking skill directly, such as working memory or attention. The trials included children and teens aged 3 to 18 with ADHD. Fifteen trials, reported in 16 papers, met the entry criteria, and the abstract reports 759 children in all.
When symptoms were rated by the people closest to the training, who usually knew which group a child was in, training improved total ADHD symptoms and inattention. These gains shrank a lot when the raters were probably blinded. Counting only trials with an active control, the effects on core symptoms were no longer statistically significant. Effects on hyperactivity and impulsivity were not significant.
Children did better on untrained lab tests of verbal and visual working memory. Parents rated executive function as better, but blinded evidence could not confirm this. Lab tests of inhibition or attention, reading and arithmetic showed no significant effects. Working memory training on its own had no effect on ADHD symptoms.
Programs aimed at several thinking processes showed a large effect on total symptoms by the closest raters, but only 4 trials had probably blinded measures, too few to confirm it. Only 5 trials analyzed everyone in their assigned group, which may have inflated some effects.
The authors state that the hope that cognitive training can improve academic performance is not supported by empirical evidence.
The numbers Stats and what the terms mean
The statistics behind the plain-language claims above.
- Cortese, 2014: total ADHD symptoms, rated by the raters closest to the training, SMD = 0.37, 95% CI = 0.09 to 0.66.
- Cortese, 2014: inattention, rated by the raters closest to the training, SMD = 0.47, 95% CI = 0.14 to 0.80.
- Cortese, 2014: total ADHD symptoms, rated by probably blinded raters, SMD = 0.20, 95% CI = 0.01 to 0.40.
- Cortese, 2014: inattention, rated by probably blinded raters, SMD = 0.32, 95% CI = -0.01 to 0.66.
- Cortese, 2014: lab tests of verbal working memory (8 trials), SMD = 0.52, 95% CI = 0.24 to 0.80.
- Cortese, 2014: lab tests of visual working memory (5 trials), SMD = 0.47, 95% CI = 0.23 to 0.70.
- Cortese, 2014: parent ratings of executive function (6 trials), SMD = 0.35, 95% CI = 0.08 to 0.61.
- Cortese, 2014: total ADHD symptoms after training aimed at several processes, rated by the closest assessors, SMD = 0.79, 95% CI = 0.46 to 1.12. What the terms mean:
- SMD A number that shows how big a difference is, separate from whether it was statistically significant. Here it compares the change in the training group with the change in the control group.
- 95% CI A range of values around the result that fit the data reasonably well. A narrow range means a more precise result, and a wide one means a less precise result.
Source: Samuele Cortese, Maite Ferrín, Daniel Brandeis, et al.. Cognitive Training for Attention-Deficit/Hyperactivity Disorder: Meta-Analysis of Clinical and Neuropsychological Outcomes From Randomized Controlled Trials. Journal of the American Academy of Child & Adolescent Psychiatry (2014). doi:10.1016/j.jaac.2014.12.010