A study compared magnetic resonance images of brains of 35 undergraduate students and found that imaging results were the same regardless of whether the students wore a face mask during the imaging processes or not. The study was published in Communications Biology.
The COVID-19 infections started in late 2019 and the World Health Organization (WHO) declared a global pandemic already in March 2020. One of the most prominent recommendations to curb the spread of the virus was to wear a face mask in situations of person-to-person contact. This sparked a heated debate around the world. Concerns were voiced that masks are uncomfortable, inconvenient, and interfere with daily living activities. Claims were made that they made breathing harder.
Masks were declared mandatory during medical procedures, including magnetic resonance imaging. Researchers examined effects of wearing N95 face masks on respiration and found a 3% increase in resistance during inhalation. Masks indeed make breathing a bit harder, but researchers concluded that this increase was too small to be of significance for the breathing process.
But do masks affect the results of magnetic resonance imaging of the brain? Oxygen and carbon dioxide concentrations in various areas of the brain are important for magnetic resonance imaging, particularly when the so-called blood oxygen level functional magnetic resonance imaging is used (BOLD fMRI). This procedure is used to study brain function and it does this by registering changes in oxygen concentrations in various areas of the brain as the person undergoing imaging performs various tasks.
“I became interested in this topic because many people have concerns about whether wearing a mask might affect their brain function and in turn their cognition, performance or even emotional states,” said study author Benjamin Klugah-Brown, research associate professor at the University of Electronic Science and Technology of China. “This is also relevant for several brain scientists, especially since many research institutes require participants to wear a mask during fMRI experiments to adhere to the COVID regulations and researchers wonder whether it can affect brain activations.
Klugah-Brown and his colleagues asked 37 of their undergraduate students (20 females, mean age was 23.8 years) to each undergo magnetic resonance imaging twice, once wearing a mask and once without a mask. The researchers randomly assigned students to wear or not wear a mask in the first imaging procedures. Students who wore a mask during the first imaging procedure did not wear it on the second and vice versa. Brain images from two students were excluded from the analysis because they were moving their heads too much during scanning and this resulted in degraded brain images.
Students underwent imaging in the so-called rest condition (they were asked to lie still and close their eyes), but also when performing cognitive tasks of finger tapping (student is told to focus on a picture of a small cross and then asked to move his/her finger), emotional face matching (student selects the face that expresses the same emotion as the “target” stimulus by pressing a button), and working memory n-back task (student is presented a character and then has to answer whether it is present in the string of characters presented thereafter). These tasks are known to lead to more intensive brain activations and these might be dependent on the oxygen availability, that might be reduced because the face mask makes the breathing harder.
The results showed no differences in brain activation patterns between when students were wearing masks and when they were not. Although the researchers compared a number of magnetic resonance imaging parameters, no statistically significant differences whatsoever were obtained between images for which students were wearing a mask and those where they were not.
The results indicate that wearing a face mask does not affect results off magnetic resonance imaging at rest and that it also has no effect on the execution of the studied cognitive tasks by the brain.
Klugah-Brown said the study has two primary findings: “First, we did not find significant differences in brain activity or performance between wearing a mask and not wearing one. This included several functional domains, including working memory processing, motor performance and processing of facial emotion signals as well as internal processes such as mind wandering. Second, in line with general recommendations thus wearing a standard surgical mask to contain the spread of the virus from person to person is a safe approach.”
“Although wearing a mask during fMRI does not significantly impact brain activation, we only tested a comparably short interval (approx. 1 hour),” Klugah-Brown noted. “Future studies should also measure subtle variations in breathing associated with mask wearing and test effects over longer time intervals.”
The study, “Effect of surgical mask on fMRI signals during task and rest“, was authored by Benjamin Klugah-Brow, Yue Yu, Peng Hu, Elijah Agoalikum, Congcong Liu, Xiqin Liu, Xi Yang, Yixu Zeng, Xinqi Zhou, Xin Yu, Bart Rypma, Andrew M. Michael, Xiaobo Li, Benjamin Becker, and Bharat Biswal.