Overtraining not linked to altered brain chemistry
Athletes who overtrain their bodies do not seem to have changes in brain levels of serotonin, suggesting that serotonin alterations don’t cause the depression and other symptoms these athletes commonly develop.
This finding suggests that the depression that may occur in overtrained athletes may be a unique variant and may need to be treated as such, the researchers report in the International Journal of Sports Medicine.
Athletes who push their bodies too hard, or “overtrain,” can end up with a host of physical and mental symptoms that take months or even years to recover from. The effects include heart rhythm disturbances, disabling muscle and nerve pain, stomach pain and ulcers, insomnia despite heavy fatigue, and depressive symptoms.
No one is sure how these problems arise, but one theory has been that overtraining alters the brain’s transmission of the chemical serotonin—which might explain athletes’ sleep, appetite and mood disturbances.
Serotonin is believed to play an important role in depression. A class of drugs called selective serotonin reuptake inhibitors (SSRIs) treat depression by slowing down the reabsorption, or “reuptake,” of serotonin into the brain cells, making more serotonin available to act on other cells.
In the new study, researchers in Finland used an advanced brain-imaging technique to measure serotonin reuptake in 12 overtrained athletes and 11 healthy ones. The athletes were scanned at the start of the study, and again one year into the overtrained athletes’ recovery.
In addition to their physical symptoms, all of the overtrained athletes had some degree of depression.
Despite this, however, there were no clear differences in serotonin reuptake between the two groups of athletes, according to the researchers. What’s more, they found no correlation between serotonin transmission and the severity of the athletes’ depression.
This was a surprise finding, suggesting that the depression of overtrained athletes “may be its own variant,” write Dr. Arja Uusitalo of Helsinki University Central Hospital and colleagues.
It’s too soon to say serotonin plays no role in the effects of overtraining, Uusitalo told Reuters Health. Other aspects of serotonin activity in the brain should also be studied, the researcher said.
But if serotonin does have little to do with overtraining, it could affect the treatment of athletes’ depression.
“According to this finding,” Uusitalo said, “it is possible that some other kind of depression medication than SSRIs would be better for the overtrained athletes.”
SOURCE: International Journal of Sports Medicine, September 2006.
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