Art Kramer on the Link between Physical Fitness & Cognition
Scientist Interview: October 2011
An analysis of Essential Science IndicatorsSM from Thomson Reuters shows that the work of Dr. Art Kramer has had the highest percent increase in total citations in the field of Neuroscience & Behavior over a recent update period. His record in this field includes 44 papers cited a total of 1,532 times between January 1, 2001 and June 30, 2011. He also ranks among the top 1% among researchers in Psychiatry & Psychology. His overall record in the database includes 141 papers cited a total of 3,848 times.
Kramer is the Swanlund Professor of Psychology & Neuroscience as well as the Director of the Beckman Institute for Advanced Science and Technology at the University of Illinois at Urbana-Champaign.
BELOW, SCIENCEWATCH.COM CORRESPONDENT GARY TAUBES TALKS WITH HIM ABOUT HIS HIGHLY CITED WORK.
What prompted your initial interest in cognitive training, and particularly the effect of physical activity?
I have always been interested in enhancing human performance and brain health. I was an athlete as a young man, but also liked science quite a bit. I'd been doing work on training for many years, even as a graduate student. I got away from that for a while when I had an opportunity to extend some of the work and do this kind of work on fitness training effects on the brain and on cognition.
We certainly know that improving fitness is a good way to reduce risk of many chronic diseases, but we knew much less about fitness as a means to enhance memory, decision making, and the brain circuits that underlie them. I was interested in that link. My doctorate was a combination of cognitive psychology and neuroscience at the University of Illinois many years ago. Then I did work on issues of human performance and brain function, but less so on learning and cognitive enhancement in the brain, plasticity. That came later.
Is the work that sparked your highly cited 2004 PNAS paper—"Cardiovascular fitness, cortical plasticity, and aging," (Colcombe SJ, et al., 101: 3316-21, 2 March 2004)?
We had done some behavioral research before that. We published a paper in Nature in 1999, examining the effects of fitness training in older, sedentary folks (Kramer AF, et al., "Ageing, fitness, and neurocognitive function," 400: 418-9, 29 July 1999). Cognition as assessed by computer-based kinds of tests, not unlike an SAT or ACT or GRE, that kind of thing, but to assess a variety of different perceptual, cognition and action abilities.
"Given the way our society is changing, maybe too much technology that doesn't engender enough movement can be problematic."
This was the next step, or one of the next steps. And that was to link changes in fitness improvement to changes in brain—in that case it was brain function, but we've also looked at brain structure—to changes in cognition as measured in these computer-based tests. It was an attempt to bring together the brain measures, the neuroimaging measures, with the behavioral or cognitive measures. Then to try to start and make the link between the animal work on what people call complexity or enriched environments, of which exercise and the opportunity for physical activity is part, to the human work.
Of course, the animal work is done at a different level, also looking at behavioral measures of learning and memory. The measurement of cognition in non-human animals is often rather crude compared to what we do with humans. But what they do well is measurement of the underlying cellular and molecular mechanisms. And by adding some neuroimaging to what we were doing with humans allowed us to bring our work a little closer to the animal work. But we were also able to keep the advantages of working with humans—that is, the sophisticated measures of cognition and human performance.
How did you carry out the trial and what did you find that prompted your colleagues in the field to reference this paper so frequently?
Well, we did two studies in that paper. One was a cross-sectional study in which we looked at individuals who differed in fitness or physical activity, and we were interested in whether those individuals differed in terms of the efficiency of the brain networks that supported a particular process called selective attention, which is the ability to focus on what's important and exclude or inhibit information that's less important as you process this information—in this case, from a visual environment.
The other one was longitudinal. It was a randomized controlled trial, in which volunteers were allocated to either an aerobic fitness group or a toning and stretching control group. The participants in both groups came into the gym the same amount of time, but they either walked for 45 minutes per session or performed toning and stretching with an instructor. In the cross-sectional study we found efficiencies for those that were higher fit in terms of the brain network we examined and in terms of better performance on the selective attention tasks.
In the longitudinal experiment, everyone was low fit when we began the experiment. It was a six-month intervention; they came into the gym three days a week, an hour a day, either doing aerobic exercise, which was mostly walking further and faster—not really fast, these were pretty modest changes—or toning stretching, yoga poses, things like that.
We found that in the aerobic group, just like the high-fit, cross-sectional people, people became more fit in a cardio-respiratory sense and their efficiency in performing the selective attention tasks improved, as did the efficiency of the brain networks that supported performance. So we had nice compatible effects between the cross-sectional experiment, which doesn't allow us to establish causality, and the randomized controlled trial, which does allow us to establish causality.