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Photo Credit: Bob Kozel
Scientific Frontline: Extended "At a Glance" Summary: Sex-Based Differences in Concussion EEG Profiles
The Core Concept: Recent neuroscientific research demonstrates that biological sex fundamentally influences the brain's baseline electrical profile. This physiological variance indicates that male and female athletes require distinct baseline metrics for the accurate assessment and management of sport-related concussions.
Key Distinction/Mechanism: Traditional concussion protocols rely heavily on subjective symptoms or cognitive and physical performance tests, which can be easily skewed by athlete motivation or fatigue. Conversely, utilizing resting-state electroencephalograms (EEGs) provides an objective physiological measure, revealing that female athletes inherently present higher baseline beta wave power than males, rendering generic, cross-sex baselines neurologically inaccurate.
Major Frameworks/Components:
- Electroencephalography (EEG): A quantitative method used to record the electrical profile of the brain, offering an objective assessment of neurophysiological state and injury recovery.
- Beta Waves: Rapid brain waves (12–30 hertz) associated with alertness, vigilance, and acute stress, which researchers identified as naturally higher in young female athletes prior to any injury.
- Theta Waves: Slower brain waves linked to critical cognitive functions such as attention, working memory, and decision-making. Researchers observed a downward trend in theta wave activity across both sexes following a concussive impact.
- Autonomic Nervous System Indicators: Physiological markers, such as heart rate variability, which scientists are proposing to combine with EEG data to formulate a more comprehensive, multi-system diagnostic tool.
Branch of Science: Neuroscience, Psychology, and Sports Medicine.
Future Application: The targeted development of objective, sex-specific clinical tools that synthesize EEG readings with cardiovascular metrics to accurately track brain recovery and establish strict, biologically sound criteria for returning athletes to active play.
Why It Matters: Because the outward symptoms of a concussion are highly subjective and vary widely from person to person, objective diagnostic criteria are imperative for athlete safety. Recognizing the intrinsic biological differences in brain activity prevents the misinterpretation of post-injury data, keeping athletes off the field while crucial cognitive functions—such as short-term memory and rapid decision-making—remain compromised.
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| Mariane Doucet Photo Credit: Courtesy of Mariane Doucet |
Concussions are among the most difficult injuries to assess in sports. The symptoms—fatigue, trouble concentrating, headaches, and anxiety—vary widely from one athlete to the next, which can make a safe return to play hard to navigate.
A research team based at Université de Montréal worked with Cégep Montmorency to better understand what happens inside an athlete’s brain before and after a concussion and to determine whether these changes differ between young women and men.
The team, led by Mariane Doucet, then a doctoral student supervised by Michelle McKerral, a professor in UdeM’s Department of Psychology, examined the resting electroencephalograms (EEGs) of 115 student-athletes between the ages of sixteen and twenty-two.
Of those, thirty-one were women. Thirty of the athletes, eight of whom were women, later suffered a concussion during training or competition and were re-evaluated using the same measures.
One of the most striking findings of the study was the pre-concussion differences between the sexes. At baseline, the young women had higher beta wave power—rapid waves between 12 and 30 hertz (Hz)—than the young men.
High levels of low-beta power (between 12 and 20 Hz) are generally associated with heightened alertness and vigilance, though in certain contexts they can also signal stress or anxiety.
An increase in high-beta power (between 20 and 30 Hz) is more specifically associated with stress or anxiety.
A Different Approach
This finding is significant because EEG analyses have often lumped men and women together to calculate average baselines, an approach that may obscure significant biological differences.
“The brains of female and male athletes do not necessarily have the same ‘electrical profile’ at the outset,” Doucet said. “This distinction is important when we are trying to detect the effects of a concussion.”
The observed postconcussion changes must be interpreted with greater caution, Doucet said. As the number of concussed athletes in the sample was smaller, the conclusions remain exploratory.
While no statistically significant differences can be confirmed with certainty, a trend did emerge: there was a decrease in theta waves following injury in both males and females.
Theta waves are often linked to attention, working memory, and decision-making—functions that are frequently disrupted after a concussion.
“A decrease in theta waves could reflect disturbances in certain cognitive functions, such as the ability to concentrate, retain information in the short term, or make quick decisions,” Doucet said.
In a sports context, these functions are crucial, she added. Players who come back too soon may have more trouble following the action, anticipating movements, or reacting effectively, even if their subjective symptoms appear to have faded.
No Single Profile
Doucet believes there is probably no single brain signature indicative of concussion. There may be multiple profiles, depending on the individual, the type of impact, and the person’s history.
Scientists are therefore looking for tools that are more objective than the tests currently in use, which are often based on cognitive or physical performance. The results of these tests can vary depending on the athlete’s motivation, level of fatigue, and performance on the baseline test taken before the season began.
EEGs could potentially offer a more objective physiological measure of recovery that could be used to track the brain’s progress after an injury. However, Doucet remains cautious: a clinical tool ready for use in the field is still a distant prospect.
“The next step could involve combining several types of physiological measurements,” she said. “We’re particularly interested in heart rate variability, which is an indicator of autonomic nervous system function.”
This approach could eventually improve athlete monitoring and provide more reliable criteria for deciding when it is safe to start playing again, she added.
Published in journal: Neuroscience
Authors: Mariane Doucet, Hélène Brisebois, Anne-Catherine Gauthier-Lamer, and Michelle McKerral
Source/Credit: Université de Montréal | Béatrice St-Cyr-Leroux
Edited by: Scientific Frontline
Reference Number: ns061926_02