O mental fatigue it can be a problem for thousands of people around the world, especially after a stressful day at work. Now, according to a study published in the scientific journal Current Biologythe cause of the mental exhaustion may have finally been found.
According to the researchers, prolonged cognitive work over several hours helps build up toxic byproducts in the brain, which can alter control over decisions and, for example, make a person choose actions that require less cognitive effort as a result of mental fatigue.
“Influential theories have suggested that fatigue is a kind of illusion invented by the brain to make us stop what we are doing and turn to a more fulfilling activity. But our findings show that cognitive work results in a real functional change – accumulation of harmful substances,” said one of the researchers at Pitié-Salpêtrière University, Mathias Pessiglione.
Researcher Antonius Wiehler, along with Pessiglione and other colleagues, sought to understand what mental fatigue is and why our brain accumulates fatigue — unlike computers, which can work continuously. So they used magnetic resonance spectroscopy (MRE) to understand brain chemistry in stages of mental fatigue.
Two groups were analyzed during the study, one with people who had to mentally strain themselves to accomplish cognitive tasks and the other with participants who had simpler tasks. After the research, they noticed that the group that wore out the most showed signs of fatigue and higher levels of glutamate in the prefrontal cortex.
Thus, research points out that the accumulation of glutamate may be responsible for the symptoms caused after mental fatigue. In future studies, the researchers want to find out why the prefrontal cortex is so susceptible to glutamate and, consequently, to fatigue.
For now, they say there is no miraculous way to solve the problem of cognitive fatigue. “I would use good old recipes: rest and sleep! There is good evidence that glutamate is cleared from synapses during sleep.”
ARTICLE Current Billology: doi.org/10.1016/j.cub.2022.07.010