Overview

Concussions are the most common type of mild traumatic brain injury, and they usually occur in sport-related accidents. Despite this, both men and women can experience concussions outside the world of sports. 

But, do concussions affect males and females differently?

This article aims to address the sex differences related to concussions, by highlighting variations in brain structure and hormones, as well as the incidence rates and symptom presentation of concussions in men and women.

What is a concussion?

A concussion is a form of traumatic brain injury (TBI), whereby a forceful impact to the head can damage nerves and blood vessels, leading to altered brain function.¹ Whilst categorising concussions under TBI can sound distressing, this form of head injury is often not serious and the symptoms are usually short-term. 

Each concussive event is unique due to different forces and orientations of the body changing the parts of the brain that are affected. However, concussions generally involve either a direct impact from a moving object or the individual hitting a stationary object. 

Common causes 

Concussions are most often caused by direct trauma to the head, which may come in the form of:¹

• Falling over
• Being in a car accident
• Whiplash
• Getting hit
• Sport-related collision

Typical symptoms 

Typical symptoms of concussion include:¹

• A brief loss of consciousness (does not have to be related to a diagnosis)
• Headache
• Confusion
• Memory loss before, during and after the impact
• Vision problems such as blurry vision, seeing stars or double vision

Do symptoms differ between males and females?

Both sexes can present with similar symptoms in response to a concussion. Nonetheless, research suggests that females are more likely to experience headaches and fatigue, whilst their male counterparts report feelings of restlessness and a greater sensitivity to noise.²

Females are also more likely to experience long-term negative symptoms, including memory problems and headaches, up to one year after their concussion when compared to males.³

Sex differences in concussion incidence 

Worldwide, it is estimated that almost 56 million people will suffer a concussion each year.⁴ Measuring concussion statistics between males and females is challenging, as there are many questions that come into play in order to determine accurate values…

What is the percentage of males vs females who get concussed? 

Who is more likely to get concussed from the same incident/sport? 

Who is more likely to report symptoms of concussion? 

Or conversely, who is more likely to keep symptoms to themselves?

Recent research has suggested that when competing in the same sport, females are 1.4x more likely to sustain a concussion than males.⁵ This doubles in game settings.⁶

Additionally, the disparity in concussion incidence is in part related to gender differences, as well as biological sex.⁷ Men tend to make up the majority of those that visit A&E, although this is likely due to their greater participation in high-risk sports (e.g. boxing, rugby).⁸ 

Concussion incidence data is also largely dependent on self-reporting, and it is known that women have a greater intention of reporting symptoms than men.⁵ Therefore, it is difficult to say whether the statistics are accurate or have been influenced by reporting bias.⁹

Physiological and anatomical differences between the sexes

Brain structure 

The differences in brain structure between the sexes could explain why females are more prone to concussion than males.

Communication between the two hemispheres of the brain occurs along a central passage called the corpus callosum.¹⁰ This is a thick bundle of cell protrusions called axons, that are individually wrapped in an insulating layer to allow for quick signalling between cells (i.e., myelin sheath).¹⁰ If the myelin sheath becomes damaged, cell signalling slows down. This can lead to the feelings of confusion or brain fog, seen after a concussion.¹¹

Research suggests that females have a larger proportion of smaller axons when compared to males, meaning that they are more vulnerable to axonal damage.⁸ This is a possible explanation to why females are more likely to become concussed than males, after the same incident.⁸

Additionally, females have been shown to use both sides of their brain for most tasks, whereas males tend to use one side.¹² Concussions put a strain on the corpus callosum (i.e., the part of the brain connecting both hemispheres), and since women seem to have more activity in this brain area, women might experience more concussion symptoms than men. 

Hormones

Surprisingly, hormones are thought to have a considerable effect on the intensity of symptom presentation for concussions. The menstrual cycle is controlled by several hormones, each having different roles to play across its four phases:¹³

1. Menstruation
2. Follicular phase
3. Ovulation
4. Luteal phase

Research into concussion and the menstrual cycle has highlighted particular interest in the luteal phase; where the level of progesterone is at its highest. Concussions occurring during the luteal phase, or the last 2 weeks of the menstrual cycle, are associated with worse symptoms when compared to concussion in the first 2 weeks of the cycle.¹⁴

Researchers believe that a concussion during the luteal phase causes progesterone to suddenly drop.^{14, 15}  It is this ‘progesterone withdrawal’ that is thought to trigger more intense symptoms when compared to males, who have continually low progesterone, and females who are in the first half of their menstrual cycle.¹⁴

Anatomy 

Another factor that influences concussion incidence is neck strength. Males are associated with greater neck girth and stronger neck muscles than females.¹⁶ This reduces the risk of concussion by increasing the stability of the head to prevent whiplash.¹⁶

Repetitive concussions 

Particularly in those who participate in high-risk sports, the possibility of sustaining multiple concussions in their lifetime is greater. Whilst one-off concussions are unlikely to cause any long lasting damage, repetitive mild traumatic brain injuries can lead to a disorder called chronic traumatic encephalopathy (CTE).¹⁷

Previously mistaken for Alzheimer’s disease due to its dementia-like symptoms, CTE is the progressive degradation of the brain tissue from damage to neurons caused by repetitive injury.¹⁷ High-risk sports have been historically male-dominated, there is a strong male bias in the number of CTE cases.¹⁸ However, if females are more susceptible to concussion than males, the number of females with CTE are likely to increase, as more women compete in such high-risk sports over the coming years. 

Summary

Acknowledging the ways in which males and females are differently affected by concussions is vital in our understanding of the condition. By using the information that females are at a greater risk of concussion during sport, health asafety measures should be adjusted to ensure adequate prevention is taken. Symptom presentation is also slightly different between the sexes, with men being less inclined to report their symptoms than women, possibly due to social pressure. Understanding these differences will help to better support individuals both when seeking treatment, and in their  recovery.