Jul 18, 2012
For a number of reasons, there remains an important need to develop research supported treatments for ADHD in addition to medication and behavior therapy.
Regarding medication, not all children benefit from taking it, some experience intolerable side effects, and many continue to struggle even when medication provides some benefit. Behavior therapy can be difficult for parents and teachers to consistently implement, and often helps but does not eliminate a child’s behavioral problems. Furthermore, neither treatment yields positive changes that persist when the treatment is discontinued. Finally, despite numerous studies documenting the short– and intermediate term benefits of these treatments, evidence of their impact on children’s long-term success is less evident.
One relatively recent development in the realm of ADHD treatments is working memory training. Working memory (WM) refers to the ability to hold and manipulate information in mind for subsequent use and is critically important for a variety of learning activities. For example, when a child is asked questions about a story he has read, working memory allows the child to retain and review the story information in mind to answer the questions. In doing mental math, working memory is used to hold the digits in mind and manipulate them, e.g., add or subtract, to generate the answer.
Working memory is also important in the control of attention and is a strong predictor of academic success. It is deficient in many individuals with ADHD; in fact, some researchers believe that working memory deficits are central to ADHD and underline the inattentive and hyperactive-impulsive behavior that characterizes the disorder. You can learn more about working memory and ADHD here.
Several years ago I reviewed a study of working memory training for ADHD that yielded promising findings. Children were randomly assigned to receive either high intensity (HI) or low intensity WM training. The HI treatment involved performing computerized WM tasks, e.g., remembering the sequence in which lights appeared in different portions of a grid, recalling a sequence of numbers in reverse order, where the difficulty level was regularly adjusted to match the child’s performance by increasing or decreasing the items to be recalled. This is described below as ‘adaptive’ training because the difficulty level adapts to match the child’s capability. In this training condition, children are consistently challenged to expand their working memory capacity.
In the LI condition, the tasks were similar but the difficulty remained low throughout, i.e., the number of items did not increase when children responded correctly. For these children, their working memory capacity was not consistently challenged and was not expected to grow as a result. This served as the control condition.
Training was conducted 5 days a week over a 5 week period; each session lasted approximately 30 to 40 minutes. Following treatment, children who received high intensity training showed stronger working memory performance than children in the control condition; these gains were evident on working memory tasks that had not been trained and remained evident 3 months after training ended. Furthermore, only children who received high intensity training showed significant declines in parent ratings of ADHD symptoms showed significant and meaningful declines for children. These declines remained evident 3 months later.
Although these were very positive findings, a limitation was that no treatment effects were found for teacher ratings of children’s behavior. Thus, there was no indication that benefits observed by parents, and mirrored in the working memory assessments, had generalized to the classroom. Given the need to improve behavior at school for children with ADHD, it is concerning that a similar pattern of findings, i.e., training related gains in working memory performance and in parent ratings of children’s behavior, but less evidence of benefits observed by teachers, has emerged in subsequent studies.
Newly Published Study
A study published online recently in Neurotherapeutics [Green et. al., (2012). Will working memory training generalize to improve off-task behavior in children with attention-deficit/
Participants were 26 children (18 males; ages 7 to 14 years old) who were randomly assigned to receive adaptive working memory training or the low intensity control training. Ten children were on medication and remained on meds during the study; this was controlled for in the analyses.
The training program used was Cogmed Working Memory training (the researchers had no affiliation with Cogmed). The standard training protocol of 5 sessions per week over 5 weeks was employed. Per standard Cogmed procedures, training was done at home and was monitored remotely by a qualified coach to help ensure the protocol was followed.
The main study outcome was children’s behavior during the Restricted Academic Situations Task (RAST). During the RAST, which takes place in a lab setting, children are instructed to complete a series of academic work sheets for 15 minutes, and not to leave their seat, or touch any of the toys or games in the room, during that time. The child is left alone to complete the work and their behavior is observed from behind a one-way mirror. The child’s behavior is coded for the amount of off task behavior, e.g., looking away from the paper, getting out of his or her seat, fidgeting, vocalizing, or playing with objects unrelated to the task.
The task thus allows for highly controlled behavioral observations and is frequently used to evaluate the effect of medication on ADHD behaviors in pharmaceutical trials. It is sensitive to moment to moment off task behavior that a teacher or parent might not detect.
The main question asked in this study was whether children who received adaptive training would show less off task behavior during the RAST than children in the control condition. If so, it would indicate a positive treatment effect of working memory training that generalized to a setting highly relevant to behavior in school. Observations of treatment and control children was made by a trained observer who did not know which group — adaptive treatment or control — each child was in.
In addition to the RAST, children’s working memory performance on tasks that differed from those used in training (the Working Memory Composite from the WISC-IV) and parent behavior ratings were obtained.
Impact on Working Memory - Consistent with what has been reported in prior working memory training studies, children receiving adaptive training showed a significant increase in the working memory score on the WISC-IV after training; children in the control condition did not.
Rating scales - Both groups showed a decline on parents’ ratings of ADHD behaviors and this did not differ between the groups. Baseline scores for children in the adaptive training group were lower than in the control group so they may have had less room for improvement.
Behavior during the RAST - The main outcome measure from the RAST was the amount of off task behavior, i.e., looking away from the work sheet rather than focusing on it, during the 15 minute seat work period. At baseline, scores for each group were equivalent. Following training, when the RAST was readmininstered, off-task behavior for children in the control group remained at their baseline level. For the adaptive training group, there was a pronounced and statistically significant decline. Adaptively trained children were also less likely to play with objects during the task. Differences in the other behavior categories — fidgeting, leaving the seat, and vocalizing — were not significant.
Summary and Implications
This is an important study — both for Cogmed Working Memory Training specifically and the cognitive training field in general. The results strongly suggest that working memory training can yield reductions in off task behavior during academic work for children with ADHD. This has not been previously demonstrated and begins to address an important gap in the research base on working memory training for ADHD, i.e., the limited indication of training effects that generalize to the classroom. While the RAST reflects a controlled observation setting rather than an actual classroom, behavior during the RAST does correlate with in class behavior. And, it is a frequently used and accepted measure for determining medication treatment effects for ADHD.
The study has several strengths including a carefully diagnosed sample, the use of random assignment, an appropriate control group, the use of multiple outcome measures, and observers who were blind to children’s treatment assignment. These are all key elements of a carefully designed intervention trial.
As with any single study, there are also limitations to note. Key among these is a relatively small sample size. Thus, replication with a larger sample would certainly be warranted. And, although the RAST provides a valid and highly controlled setting to observe behavior, future studies should also include observations of children’s behavior in their actual classroom. Although this makes for a more complex study, the classroom is ultimately the setting where increases in focused, on task behavior during academic work needs to occur. Finally, this study did not follow participants beyond the end of treatment so the duration of benefits observed is not known.
These limitations not withstanding, the authors have presented important new data on the potential benefits of working memory training by demonstrating generalization of training benefits to a relevant setting for academic work. Given the growing interest in working memory training — and other forms of cognitive training — it is likely that results from a number of additional studies on these approaches will become available over the next several years.
– Dr. David Rabiner is a child clinical psychologist and Director of Undergraduate Studies in the Department of Psychology and Neuroscience at Duke University. His research focuses on various issues related to ADHD, the impact of attention problems on academic achievement, and attention training. He also publishes Attention Research Update, a complimentary online newsletter that helps parents, professionals, and educators keep up with the latest research on ADHD.
Previous articles by Dr. Rabiner: