Intense exercise increases the levels of two common neurotransmitters that are linked to depression.
Gamma-aminobutyric acid (GABA) and glutamate are both involved in depression and other neuropsychiatric disorders.
Professor Richard Maddock, the study’s first author, said:
“Major depressive disorder is often characterized by depleted glutamate and GABA, which return to normal when mental health is restored.
Our study shows that exercise activates the metabolic pathway that replenishes these neurotransmitters.”
The research involved 38 people who exercised on a stationary bicycle for a period.
Their neurotransmitter levels were compared with a control group who did not exercise.
Both glutamate and GABA levels increased in those who exercised compared with those who did not.
The brain actually uses vast quantities of energy when we are exercising, Professor Maddock said:
“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.
Apparently, one of the things it’s doing is making more neurotransmitters.”
The finding may help explain why people can become suddenly fatigued while exercising:
“It is not clear what causes people to ‘hit the wall’ or get suddenly fatigued when exercising.
We often think of this point in terms of muscles being depleted of oxygen and energy molecules.
But part of it may be that the brain has reached its limit.”
The study’s results are encouraging, concluded Professor Maddock:
“There was a correlation between the resting levels of glutamate in the brain and how much people exercised during the preceding week.
It’s preliminary information, but it’s very encouraging.
We are offering another view on why regular physical activity may be important to prevent or treat depression.
Not every depressed person who exercises will improve, but many will.
It’s possible that we can help identify the patients who would most benefit from an exercise prescription.”
The study was published in The Journal of Neuroscience (Maddock et al., 2016).
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