Richard Maddock and his team conducted MRI exams of people before and after vigorous exercise to determine the effect of exercise on neurotransmitters. Credit: Image courtesy of University of California – Davis Health System
Intense exercise increases levels of 2 common neurotransmitters – glutamate and GABA The finding offers new insights into brain metabolism and why exercise could become an important part of treating depression and other neuropsychiatric disorders linked with deficiencies in neurotransmitters, which drive communications between the brain cells that regulate physical and emotional health.
“Major depressive disorder is often characterized by depleted glutamate and GABA, which return to normal when mental health is restored,” said Prof. Richard Maddock. “Our study shows that exercise activates the metabolic pathway that replenishes these neurotransmitters.” The research also helps solve a persistent question about the brain, an energy-intensive organ that consumes a lot of fuel in the form of glucose and other carbohydrates during exercise. What does it do with that extra fuel?
“From a metabolic standpoint, vigorous exercise is the most demanding activity the brain encounters, much more intense than calculus or chess, but nobody knows what happens with all that energy,” Maddock said. “Apparently, one of the things it’s doing is making more neurotransmitters.” The research also hints at the negative impact sedentary lifestyles might have on brain function, along with the role the brain might play in athletic endurance.
The team studied 38 healthy volunteers. Participants exercised on a stationary bicycle, reaching around 85% of their predicted maximum heart rate. To measure glutamate and GABA, the researchers conducted a series of imaging studies using a powerful 3-tesla MRI to detect nuclear magnetic resonance spectra, which can identify several compounds based on the magnetic behavior of hydrogen atoms in molecules.
The researchers measured GABA and glutamate levels in 2 different parts of the brain immediately before and after 3 vigorous exercise sessions lasting between 8 and 20 minutes, and made similar measurements for a control group that did not exercise. Glutamate or GABA levels increased in the participants who exercised, but not among the non-exercisers. Significant increases were found in the visual cortex, which processes visual information, and the anterior cingulate cortex, which helps regulate heart rate, some cognitive functions and emotion. While these gains trailed off over time, there was some evidence of longer-lasting effects.
“There was a correlation between the resting levels of glutamate in the brain and how much people exercised during the preceding week,” Maddock said. “It’s preliminary information, but it’s very encouraging.”
These findings point to the possibility that exercise could be used as an alternative therapy for depression. This could be especially important for patients under age 25, who sometimes have more side effects from selective serotonin reuptake inhibitors (SSRIs).
For follow-up studies, Maddock and the team hope to test whether a less-intense activity, such as walking, offers similar brain benefits. They would also like to use their exercise-plus-imaging method on a study of patients with depression to determine the types of exercise that offer the greatest benefit.
http://www.ucdmc.ucdavis.edu/publish/news/newsroom/10798
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