Science Watch

In treating people with attention deficits caused by brain damage, the prevailing strategy has been to tackle the injury directly, much as a physical therapist exercises injured muscles. But a new study suggests that it might be more effective for rehabilitation therapists to help patients bypass damage and learn to perform attentional tasks using alternative brain processes.

Attention deficits are among the most common cognitive problems to result from traumatic brain injuries and stroke. They can impair people's ability to sustain attention on a topic over time, nimbly shift their focus between activities and avoid being distracted by irrelevant sources of information--skills needed for driving, reading, conversing and many other everyday activities.

For decades, scientists and clinicians have sought effective treatments for attention deficits that arise from brain injuries. The treatment of choice has long been to have patients practice abstract cognitive exercises designed to directly restore impaired attention processes.

"The idea is that attention and other cognitive faculties are like muscles and that through exercising them, you can actually restore function to the neural circuits that underlie cognition," explains Norman Park, PhD, a psychologist and neurorehabilitationist at the Baycrest Centre for Geriatric Care in Toronto.

But research in other areas of cognitive rehabilitation has underscored the difficulty of directly restoring damaged brain function, leading some researchers to question this so-called direct retraining strategy. And a meta-analysis of research on the effectiveness of attention rehabilitation by Park and colleague Janet Ingles, PhD, a postdoctoral fellow at Dalhousie University in Halifax, Nova Scotia, supports that skepticism.

More promising than direct retraining, their analysis suggests, is a lesser-used therapy that teaches patients to deploy alternative cognitive strategies to accomplish the specific tasks they're having trouble with. The meta-analysis, published in this month's issue of Neuropsychology (Vol. 15, No. 2), is the first such quantitative review of research on attention rehabilitation.

Comparing strategies

In their meta-analysis of 30 studies conducted between 1966 and 1997, Park and Ingles found that the lion's share, 26, tested the direct retraining strategy for treating attention deficits while only four examined what the researchers call a "specific skills" strategy. In total, the studies examined 359 adults who had experienced either a stroke or a traumatic brain injury from a blow to the head.

Those who received direct retraining practiced repetitive cognitive exercises that require attention. In one rehabilitation program, for example, patients pressed a buzzer whenever they heard the number three. In another, patients with difficulty dividing their attention between two tasks practiced performing two simultaneous activities, such as circling a particular letter whenever it appeared on a sheet of paper and pressing a buzzer whenever they heard a number spoken aloud on a tape that was two greater than the immediately preceding number.

In the specific skills approach, rehabilitation therapists provide patients with exercises that focus on particular, practical skills that require attention. In one study, for example, researchers examined patients whose brain injuries affected their ability to drive a car, a skill that requires one to focus attention on several objects and to shift flexibly from one task to another. Using a small electric car in the laboratory, patients practiced specific driving exercises--for example, steering between pylons that were moved progressively closer together.

The rationale underlying specific skills training is that brain-injured patients can learn to accomplish functionally significant skills by bypassing impaired neural processes and instead capitalizing on intact processes.

"The idea is to have patients actually train on the tasks that are of greatest functional significance to them, in contexts that are similar to their day-to-day lives," explains Ingles. "By doing that, they learn to perform the tasks in a way that's different from what they did prior to their injury."

Aggregating across studies, Park and Ingles found that direct retraining was of little benefit to patients. Those studies that compared patients' cognitive functioning before and after rehabilitation therapy suggested improvement, but those that included a control group revealed no such effect of therapy.

That suggests, the authors argue, that any positive effects may have been attributable to patients' spontaneously improving or to their having practiced the tests before therapy began--when their baseline performance was measured--rather than to cognitive gains from direct retraining.

In contrast to the direct retraining studies, in the few studies testing a specific skills approach, patients' performance on attention tests improved significantly after rehabilitation--even when compared with a control group.

"This meta-analysis signifies a certain coming-of-age in the field of attention rehabilitation," says psychologist Ian Robertson, PhD, who conducts research on cognitive rehabilitation at Trinity College Dublin in Ireland. "There's now an accumulation of research that can be properly evaluated. This article points to a clear conclusion: If you want to change behavior, you should probably focus on specific skills, rather than on general capacity."

Mark Ylvisaker, PhD, a professor in the department of communication disorders at the College of Saint Rose in Albany, N.Y., observes, "I hope that people will take these findings very seriously and be as deliberate and thoughtful as they possibly can be in choosing where to devote research and treatment resources."

Combining approaches

Following up on the meta-analysis, Park has begun to probe which aspects of specific skills training are most critical for successfully treating attention deficits.

He suspects the answer lies in what is termed neuropsychological scaffolding--developing treatment programs that build on patients' intact abilities and slowly move them toward fuller, even if compensatory, functioning. Experiments now under way in his laboratory, Park hopes, will help clarify what types of scaffolding are most effective.

But, Park cautions, it's premature to throw out the direct retraining approach altogether. For one thing, he suggests, it's possible that direct retraining is more effective for patients whose brain damage is milder than was the case for those included in the reviewed studies.

Robertson emphasizes that future work should also look to ways that the direct retraining and specific skills approaches can be integrated.

"I'm optimistic that we can combine these two approaches if we properly anchor rehabilitation methods in the best understanding of cognitive function, as revealed by basic cognitive neuroscience," he says.

He observes that a number of brain-imaging studies have indicated that stimulating cognitive activity significantly--if temporarily--alters neuronal activity in brain regions linked to impaired function.

"What we need to do now," Robertson says, "is to build bridges between these laboratory-based procedures and practice of the relevant cognitive skills in a range of real-life situations."



This article is part of the Monitor's "Science Watch" series, which reports news from APA's journals.