Most of us know by now that successful people exercise. It’s such a status symbol that the workout routines of presidents like Bush and Obama and CEOs like Ariana Huffington and Jeff Bezos are frequently covered by the media. We know exercise is good for us, but one of the biggest appeals for high performers is the way it boosts our cognitive function. Exercise literally makes us smarter. But how exactly does that happen? Spoiler alert: it’s dopamine.
Scientists have been trying to find the exact mechanism behind the boost in brain function exercise gives us for a while. It looks like exercise boosts growth factors in the brain, which means brain cells can grow and adapt, a process called neuroplasticity. And research also finds that exercise improves neuronal efficiency, so our brain cells work faster and interact with each other better. But the actual biological link between exercise and these cognitive improvements has remained unknown. Until now.
A research team from Japan have found the missing link between exercise and better cognitive function. And they did it by studying how fast people blink their eyes.
The image of a bunch of scientists staring intensely at you and counting how fast you blink may be unsettling, but using eye blink rate to determine the impact of exercise on the brain is a brilliant insight. Here’s why: the team drew of recent neuroscience findings that suggest the spontaneous eye blink rate (sEBR) reflects the activity of dopamine in the brain.
The researchers were also aware that the dopaminergic system in the brain has been tied to both physical exercise and executive function in the brain, i.e. top-flight thinking. Neuroscientists have wondered if dopamine could be the chemical messenger that leads to the brain boost we get from exercise. But until the Japanese team made the connection with eye blinking, there has been no marker for dopamine activity that could test this.
Eye-blinking is a marker for dopamine
“We used sEBR as a non-invasive measure of dopaminergic system function to test whether it could be the missing link between aerobic fitness and cognitive function,” said first author of the study Ryuta Kuwamizu in a press release. Non-invasive means the scientists don’t need to stick their study participants with needles, so that’s a win for everyone.
First, the researchers measured the resting eye-blinking rate of 35 healthy men between the ages of 18-24. Then the study team had them exercise to the point of exhaustion. Finally, the study participants performed a color-word Stroop test, which not only has a super fun name, but also measures executive function.
During all of this, the team continued to monitor their sEBR. And during the Stroop test in particular, they used near-infrared spectroscopy to monitor cortical activation in the left dorsolateral PFC (l-DLPFC). In other words, they used a brain scan to see how the brain was performing so they could correlate that performance with the eye-blink rate.
The higher the sEBR, the higher neural efficiency of the l-DLPFC. So executive function was high the faster someone was blinking. But the sEBR also correlated with how physically fit the participants were.
“As expected, we found significant correlations between aerobic fitness, cognitive function, and sEBR,” explained Professor Hideaki Soya, senior author. “When we examined these relationships further, we found that the connection between higher aerobic fitness and enhanced cognitive function was mediated in part by dopaminergic regulation.”
This was the first study to pinpoint the neurotransmitter responsible for the boost in brain function we get from exercise. “Our data indicate that dopamine has an essential role in linking aerobic fitness and cognition,” said Kuwamizu. Further, the study authors speculate that lack of fitness could cause dopamine dysfunction, which could mean less effective thinking and poor mood.
So if it’s dopamine, wouldn’t be easier to just take something that boosts dopamine instead of hitting the gym? Unfortunately, that’s been tried and it hasn’t worked out very well for people. Since dopamine is also the key neurotransmitter in the brain’s reward system, it’s the reason crystal meth and other drugs of abuse are so addictive: they give you a dopamine boost.
So it looks like actual exercise is the way to go when we want to boost our dopamine to boost our moods and our thinking. Or, we could stimulate our brain’s dopaminergic reward center by repeating the phrase “Stroop test” five times fast. Try it: it’s delightful.