Fatter Body, Slower Brain: Two New Studies

Putting on extra pounds may damage your mental, as well as your physical, fitness but overweight middle-aged people who follow a program of high-intensity interval training can lose weight and improve their cognitive functioning.  These are the implications of two recent small studies, one headed by Timothy Verstynen, PhD of Carnegie Mellon, the other by Dr. Anil Nigam of the University of Montreal and the Montreal Heart Institute.  

In the Carnegie Mellon study, researchers examined the brains of 29 adults using functional magnetic resonance imaging.  The subjects’ body mass index scores ranged from normal to obese.  In the overweight and obese subjects there was evidence of hyper-connectivity in parts relating to memory and decision-making, indicating that the brain needed to work harder in those individuals.  These parts functioned normally in people of average weight.  The obese subjects also needed more effort to perform a decision-making task.  “As people put on unhealthy amounts of weight, the body’s energy systems begin to degrade and you can start to see the negative effect on brain circuitry, particularly areas that are important for controlling impulsive behaviors,” according to Verstynen.  The key factor seems to be inflammation, which interferes with the body’s communication system.

The Canadian research involved six subjects in their late 40’s with body mass index numbers in the “overweight” range.  Dr. Nigam said, “We worked with six adults who all followed a four-month program of twice weekly interval training on stationary bicycles and twice weekly resistance training.  Cognitive function, VO₂max and brain oxygenation during exercise testing revealed that the participants/ cognitive functions had greatly improved thanks to the exercise.”  VO₂max refers to the maximum amount of oxygen that a person’s body can use during intense exercise; it is an indicator of cardio-vascular fitness and aerobic endurance.  Participants in the study lost inches around the waist and reduced body weight but they also significantly improved performance on cognitive tasks, such as remembering pairs of numbers and symbols.

These studies suggest that exercise allows the body to recover mental as well as physical functioning, even in middle age.  Based on the descriptions I’ve read there wasn’t a huge time commitment, just four sessions per week, but the exercise was at a fairly intense level, interval training and weights.  A leisurely walk might not have the same effect on the brain, though it probably helps the body.