KHPR professor using brain waves to study depression, concussions, more

Researchers have long examined the link between exercise and major depressive disorder (MDD), with one of the earliest known published studies dating back to 1905. Then, clinical methods were limited, little was known about the effects of exercise, and data were often unreliable, but today researchers are able to use advanced technology including electroencephalography (EEG) to better understand what’s happening in the brain during exercise — and determine why it may have a positive effect for individuals with depression.

Now UNT Assistant Professor Ryan Olson is using these advanced techniques right here in his psychophysiology lab in the UNT College of Education’s Department of Kinesiology, Health Promotion and Recreation, shedding light on what functional brain activity can tell us not only about depression and anxiety, but also concussions, sleep deprivation and much more.

Depression and Exercise

Building on that seed of an idea from 1905, Olson utilizes the event-related potential (ERP) technique (derived from the EEG signal) to explore what’s happening in MDD patients’ brains and how exercise may provide antidepressive effects. In one of his recent studies, Olson and his team assembled a group of MDD patients with similar baseline levels of depressive symptoms. Participants were randomly assigned to either a moderate-intensity exercise or placebo exercise (i.e., stretching) group. Over an eight-week period, subjects performed exercise three times per week for 45 minutes during each session. ERPs were measured at the beginning and end of the eight-week intervention to determine functional changes over time.

“We found some pretty striking differences. In the exercise group, we found clinically significant reductions in depressive symptoms,” Olson said. “Whether they’re actually remitting from depression is a separate question, but on average, we found significant reductions in depressive symptoms compared to the placebo exercise group.”

Olson also saw reductions in a variable called rumination – the tendency to focus on either the past or the future and not the present, which is common in patients with MDD.

“Rumination isn’t necessarily a bad thing, it just means you can’t stop thinking about something, you can’t let it go. And that’s one of the variables we saw a change in with exercise as well, which was an interesting finding,” Olson said. “Rumination, especially on negative thoughts, is a hallmark symptom of depression; these participants are unable to let things go, try to change something in the past or think about the future.”

But Olson said the most interesting effect he observed during the study, in addition to reductions in depressive symptoms and rumination, was improvements in neurocognitive function assessed through ERPs, which is exciting to researchers because it’s getting at the potential mechanism of why they’re seeing changes in depressive symptoms.

“We’re now able to target specific aspects of cognition, like inhibition or decision-making. We know certain areas of the brain regulate those functions, so it starts to make sense when we observe exercise working through the same areas of the brain. You’re starting to answer the why,” Olson said.

Olson has been studying the effects of exercise on depression and anxiety symptoms prior to arriving at UNT last year. In one of his earliest studies, he worked to establish differences in neurocognitive function between healthy and MDD groups while performing a task of inhibition. He and his team found differences in ERP responses between the two groups, so he followed this study by targeting those differences with exercise.

“I used an acute exercise paradigm, where I had participants come in and exercise at low or moderate intensity, and I wanted to see the effects on a specific ERP waveform, the N2 component. It turns out that acute exercise does modify it,” Olson said. “So then I said, what if we perform this long term? Will this waveform stay modified, and if so, does this relate to changes in depressive symptoms?”

Event-related potentials

ERPs are an indirect measure of neural activity, Olson said. During his trials, Olson and his team measure these waveforms to see what the brain is doing — and when.

“Every time I clap or talk, your brain generates an event-related potential, meaning it’s tied to a specific event,” Olson said. “In our studies, the ‘event’ is a simple cognitive stimulus that we can manipulate to add a layer of complexity that allows us to measure different aspects of cognition. After participants complete our tasks, we can process the data and measure the amplitude and latency (timing) of the ERPs.”

And why is timing important?

“We measure in the millisecond time range because information processing happens so fast that we’re usually not aware of it,” Olson said. “Imagine making a decision on the fly. It could be the difference between getting in a car accident or not. So those timing-related questions are very important.”

Concussions: Getting Athletes Back in the Game Safely

Olson also does extensive work studying concussions. The objective is to determine whether athletes are healthy enough to return to play after experiencing a concussion as well as ensure appropriate diagnoses are being made. Olson said the current “return-to-play” criteria is for the athletes to complete sideline testing as well as a series of cognitive tasks that can easily be distorted by the athlete. For instance, athletes can purposefully underscore during the preseason in order to perform at a similar level during the season following a concussion.

“One of the classic findings in the concussion literature is there’s rarely a difference in cognitive test scores between a healthy and concussed individual. So one might think that a recently concussed athlete is healthy, yet they may have subtle cognitive deficits that may be undetectable by more traditional measures,” he said.

That’s where ERPs come in. In healthy people, ERP waveforms become larger the more difficult the cognitive task they’re doing becomes. However, this is not the case following a concussion. Olson’s research compares a non-concussed individual’s response to the concussed individual’s response, measures the difference between the two responses, and determines how long it takes for the concussed group’s responses to return to “normal” levels.

“This could be a better way of tracking recovery trajectories and making sure that an athlete is actually healthy enough to continue playing,” he said. “The great thing about this technique is that it’s extremely difficult to cheat. There’s almost no way to cheat this test because you’re generating basic neural responses.”


In addition to doing his own research in KHPR, Olson is collaborating with other researchers across campus. He’s got several ongoing projects with members of his department including Brian McFarlin, Jakob Vingren, Calvin Nite, Erin Bowman and Scott Martin. He’s also beginning work with Heidimarie Blumenthal and Anthony Ryals in UNT’s Psychology department, and with Daniel Taylor, creator of the UNT Sleep Health Research Laboratory. His work with Taylor has direct implications to UNT students: They’re researching college students and sleep deprivation.

“We’re looking at acute sleep deprivation and the effects of exercise on cognition the next day. If you stayed up all night studying, would it be a good idea to go for a jog before going on to your exam?” Olson said. “It’s also about applying it to the military and the bigger picture – when you’re sleep deprived, are you making good decisions when you need to be?”

What’s Next?

Olson said his goal for his main area of research, studying the effects of exercise on major depressive disorder, is to make sure exercise is recognized as a potential supplemental treatment for MDD patients, perhaps working together with anti-depressants.

“We’re still trying to understand some of the early exercise prescription issues – like what intensity, how long, how many weeks does it have to be, does it have to be just aerobic exercise or can you do resistance exercise? There are a lot of the basic questions we’re trying to answer right now,” he said.

The bottom line for Olson is finding applications for his research — not just for clinical populations or athletes, but also the general population.

“That’s always the question I ask of my students: So what? What is the big idea in the end? That’s an important question that we have to answer as researchers,” he said.