Written by Mayukha Kashyap
Researchers at John Hopkins Medicine are discovering new findings that can help scientists understand fatigue-related symptoms.
Picture source: www.healthline.com/health/fatigue.
We all have experienced fatigue at one point in our life. Maybe you stayed up too late one day to study and woke up feeling exhausted. Or maybe you took a trip and came back with severe jet lag, affecting your sleep schedule. Even worse, maybe you have an underlying health condition that causes you to experience fatigue regularly. But what causes fatigue, scientifically speaking, and how do we stop it? Scientists at John Hopkins Medicine have identified areas of the brain that may help with regulating fatigue.
According to Healthline, “Fatigue is a term used to describe an overall feeling of tiredness or lack of energy. It isn’t the same as simply feeling drowsy or sleepy” (O’Connell, 2020). While feeling tired is a symptom of fatigue, it is not the same.
Fatigue leads to a lack of motivation and energy, impacting productivity.
Many factors could lead to fatigue. Each factor is divided up into three categories: lifestyle, physical health, and mental health.
Lifestyle factors include physical exertion, lack of physical activity, boredom, not eating a balanced diet, and drugs. Physical health conditions include anemia, Addison’s disease, eating disorders, autoimmune disorders, and cancer. Mental health conditions include anxiety, depression, and seasonal affective disorder.
Sometimes making simple changes to one’s lifestyle is enough to combat fatigue. However, in other cases, medical professionals may have to intervene.
To better understand what part of the brain regulates fatigue, a team led by Vikram Chib, assistant professor of biomedical engineering at the Johns Hopkins University School of Medicine and research scientist at the Kennedy Krieger Institute, conducted a study with 20 people. Their ages ranged from 18 to 34, with the average age being 24, while nine out of the twenty people were female. Chib created a new way for the study patients to assess “how they feel.” Typically, medical professionals ask patients how they feel on a scale of 1 to 7; however, Chib believed this was too subjective and varied from patient to patient. He, therefore, asked the participants “to make risk-based decisions about exerting a specific physical effort” (Johns Hopkins Medicine, 2020).
Chib asked the participants to squeeze a sensor and associate their effort with how much they needed to squeeze, which standardized the entire group’s unit of effort. The participants repeated this for ten trials each until they felt fatigued. Once they felt fatigued, Chib offered them two choices. One was the “risky” choice where participants would flip a coin that would determine whether they would put no effort into their next task or put in a predetermined effort. When the predetermined effort was low, unsurprisingly, participants took the risk-free option so that they would have to put in less effort.
Using MRI scans, Chib’s team found that brain activity would increase in the insula, a part of the brain, when choosing between the two options. This finding matched up with previous research efforts. The team also found that the motor cortex was deactivated when patients were choosing between their choices.
Chib explained that when performing repeated actions that cause fatigue, the motor cortex’s activity decreases, and fewer signals are sent to the muscles.
Participants whose motor cortex activity did not change much were the most fatigued and took the risk-free option. Chib believes this means there is a discrepancy between what the participant believes they can achieve and the motor cortex’s activity.
“Essentially, the body attunes to the motor cortex when fatigued, because if the brain kept sending more signals to muscles to act, physiological constraints would begin to take over, for example, increased lactic acid, contributing to even more fatigue,” explains Chib.
In other words, the brain adjusts itself based on the motor cortex activity levels so that a person does not overdo themselves and cause physiological damage.
In the future, Chib believes their findings can help further research done about fatigue. Their findings can prompt others to find physical and chemical therapies to advance performance in people who display fatigue-related symptoms.
Sources:
Johns Hopkins Medicine. "Got fatigue? Study further pinpoints brain regions that may
control it." ScienceDaily. ScienceDaily, 26 August 2020.
<www.sciencedaily.com/releases/2020/08/200826113713.htm>.
O'Connell, Krista. “Fatigue: Causes, Diagnosis, Treatment & More.” Healthline,
Healthline Media, 22 July 2011, www.healthline.com/health/fatigue.
Patrick S. Hogan, Steven X. Chen, Wen Wen Teh, Vikram S. Chib. Neural mechanisms
underlying the effects of physical fatigue on effort-based choice. Nature
Communications,
2020; 11 (1) DOI: 10.1038/s41467-020-17855-5
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