23 April 2010. However far apart the worlds of television and scientific research may seem, they came together for a study published online in Nature on April 20. It began when the producers of a popular television show set out to learn whether brain training improves cognitive performance. The researchers, including Adrian Owen of the MRC Cognition and Brain Sciences Unit, Cambridge, United Kingdom, tested whether six weeks of online brain training would improve the cognitive performance of 11,430 healthy adults recruited through the show and its website. Owen and colleagues found that the training mainly benefited performance on the trained tasks; it did little to boost performance on other tasks, even ones closely related to those used in the training. The study’s implications for schizophrenia and other diseases that impair cognition remain unclear.
The benefits touted by certain commercially available brain-training programs include better memory, sharper thinking, faster cognitive processing, and improved concentration. The Brain Age website hints that training can “increase blood flow to the prefrontal cortex,” Posit Science claims to improve the speed and quality of information processing, and HAPPYneuron says that its program “minimizes the natural effects of brain aging by maximizing the brain's capacity to learn and its ability to adapt to new information.” Whether these electronic games cost consumers $20 or $400, however, their ability to improve overall cognition remains unproven. A review of approaches to improving cognitive function through “brain exercise” concluded that they do little or nothing to improve cognition outside of the trained tasks (Green and Bavelier, 2008), although more promising findings also appear in the literature (see SRF related news story).
To examine the effects of brain training on cognitive functioning, Owen and his collaborators in the United Kingdom conducted a massive clinical trial online. At the start, 52,617 subjects, recruited through the British Broadcasting Corporation science show Bang Goes the Theory, signed up to participate. Ranging in age from 18 to 60, they were instructed to perform certain cognitive tasks for at least 10 minutes a day, three times per week, for six weeks. To do so, they logged on to the show’s website, Lab UK.
The study randomly assigned subjects to either one of two brain-training groups or to a control group. The two training groups differed in the kind of training they received: one practiced tasks designed to improve reasoning, planning, and problem-solving, while the other received training more like that involved in many commercial brain-training programs. For instance, they practiced tests assessing a wide range of cognitive functions, including short-term memory, attention, visuospatial processing, and math. A third group consisted of control subjects whose task involved finding answers to “obscure questions” using any online resources they could find.
To detect cognitive gains, the researchers administered a neuropsychological battery at baseline and six weeks later. It consisted of four tests that assessed verbal short-term memory, spatial working memory, paired-associates learning, and reasoning. The change in scores from pre-test to post-test served as the main outcome measure and an indicator of generalized cognitive improvement. Analyses focused on the 11,430 subjects who had completed at least two training sessions during the six-week period, as well as the neuropsychological test battery before and after that time.
Due to concerns that the huge sample size would yield positive results for trivial differences, the researchers reported effect sizes rather than p-values. Not surprisingly, the training improved performance on the trained tasks. It yielded substantial effect sizes that ranged from 0.73 (99 percent CI, 0.68 to 0.79) to 1.63 (99 percent CI, 1.57 to 1.7), depending on the task, in the reasoning training group, and from 0.72 (99 percent CI, 0.67 to 0.78) to 0.97 (99 percent CI, 0.91 to 1.03) in the general training group. These numbers exceed the small effect size, 0.33 (99 percent CI, 0.26 to 0.4), seen in control subjects.
Of course, the most interesting question was whether the training gains would generalize to other tasks. Owen and colleagues found that from baseline to six weeks, the group that received reasoning training improved on four of the neuropsychological tests, while the broadly trained group improved on three. Even so, the highest effect size, 0.35 (99 percent confidence interval, 0.29 to 0.41), was small. More to the point, the control group also improved on all four tests, with similar effect sizes. When the researchers directly compared the performance of the three groups across all four tests, they found that all improved, but only slightly. Owen and colleagues conclude, “These results provide no evidence for any generalized improvements in cognitive function following brain training in a large sample of healthy adults.”
Methodological land mine or landmark?
Owen and colleagues considered a number of possible reasons for the failure to find generalized training gains. For instance, they wondered whether an insufficient training “dose” could account for the disappointing results. The average subject completed 24 sessions, but individuals varied widely in the number of sessions completed. However, in all three groups, the number of training sessions correlated only slightly with performance gains on the neuropsychological tests (largest Spearman’s rho = 0.059), although it did correlate with performance on the trained tasks. “In all three groups, whether these improvements reflected the simple effects of task repetition (that is, practice), the adoption of new task strategies, or a combination of the two is unclear, but whatever the process effecting change, it did not generalize to the untrained benchmarking tests,” write Owen and associates. However, they note,” the possibility that an even more extensive training regime may have eventually produced an effect cannot be excluded.”
The study may add to uncertainty about cognitive training for people with schizophrenia. Philip Harvey of Emory University, in a comment to SRF, raises several crucial methodological points about this study. For instance, he warns that subjects’ ideas about the desired findings of the study could have shaped the outcome. Robert Bilder, of the University of California at Los Angeles, also expresses methodological concerns, including agreeing with Harvey that healthy, high-performing subjects might have less room for improvement than patients with brain disorders. However, he thinks the study highlights the potential usefulness of the Web for conducting large-scale, behavioral phenotyping.
Helping the schizophrenic brain
Brain-training programs may interest people with schizophrenia and related disorders that cause cognitive impairments. Apparently, Posit Science thinks so; its website says that “highly promising preliminary results” support its effectiveness for various conditions that cause cognitive impairment, such as schizophrenia and Alzheimer’s disease. Actually, prior research does support the ability of a neuroscience-based training program, developed by Posit Science, to produce lasting effects on global cognition in schizophrenia, but only after 100 hours of training (see SRF related news story). In addition, a 2007 meta-analysis found that cognitive remediation programs moderately improved overall cognition in schizophrenia (McGurk et al., 2007). On the other hand, a subsequent randomized, control trial of computer-assisted cognitive training found that its benefits did not transfer to other neuropsychological or functional outcomes (Dickinson et al., 2009). Clearly, the issue remains unsettled.
While the Nature study looked at healthy, relatively young volunteers, subjects over 60 years old have also been training their brains on the television show’s Lab UK website. Owen and associates plan to follow them for a year to see if a longer training program might help these subjects, some of whom have cognitive deficits.—Victoria L. Wilcox.
Owen AM, Hampshire A, Grahn JA, Stenton R, Dajani S, Burns AS, Howard RJ, Ballard CG. Putting brain training to the test. Nature. 2010 Apr 20. Abstract