According to new research published in the journal Radiology, women’s brains are more vulnerable than men’s to injury from repeated soccer heading. The study found that regions of damaged brain tissue were five times more extensive in female layers than in males.
Female soccer players exhibit more extensive changes to brain tissue after repetitive ‘heading’ of the soccer ball. Image credit: Keith Johnston.
Soccer is the most popular competitive sport in the world, and female participation in the sport is on the rise.
Heading, in which players field the soccer ball with their heads, is a key component of the game.
Heading-related impacts have been associated with abnormalities in the brain’s white matter that are similar to those seen in patients with traumatic brain injury. Cumulative heading over a one-year period has been associated with cognitive dysfunction and microstructural changes to the brain’s white matter.
“In general, men do a lot more heading than women, but we wanted to specifically examine if men and women fare similarly or differently with a similar amount of exposure to repeated impacts to the head,” said led author Professor Michael Lipton, from the Albert Einstein College of Medicine and Montefiore Medical Center.
In the study, Dr. Lipton and co-authors performed diffusion tensor imaging (DTI), a form of MRI, on 49 male and 49 female amateur soccer players.
Both groups ranged in age from 18-50 with a median age of 26, and both groups reported a similar number of headings over the previous year (an average of 487 headings for the men and 469 for the women).
DTI produces a measurement, called fractional anisotropy (FA), which characterizes the movement of water molecules in the brain. In healthy white matter, the direction of water movement is fairly uniform and measures high in FA. When water movement is more random, FA values decrease.
“A decline in FA is an indicator of changes in the white matter microstructure that may be indicative of inflammation or loss of neurons, for example,” Dr. Lipton said.
For the study, the team compared white matter FA values among the male and female soccer players.
The analysis revealed that while both men and women experienced lower FA values related to more repetitive heading, women exhibited lower FA levels across a much larger volume of brain tissue.
“In both groups, this effect we see in the brain’s white matter increased with greater amounts of heading. But women exhibit about five times as much microstructural abnormality as men when they have similar amounts of heading exposure,” Dr. Lipton said.
Just why women might be more sensitive to head injury than men isn’t known. The scientists speculate that differences in neck strength, sex hormones or genetics could play a role.
The changes in FA were subclinical, meaning they didn’t produce overt clinical findings such as altered thinking ability. But those FA changes are still cause for concern.
“In various brain injuries, including chronic traumatic encephalopathy [a degenerative brain disease found in athletes, military veterans, and others with a history of repetitive brain trauma], subclinical pathology develops before we can detect brain damage that affects function,” Dr. Lipton said.
“So before serious dysfunction occurs, it’s wise to identify risk factors for cumulative brain injury — such as heading if you’re female — so that people can act to prevent further damage and maximize recovery.”
The researchers were also able to identify specific regions of the brain where frequent heading was associated with lower FA: three brain regions in men and eight brain regions in women.
“The important message from these findings is that there are individuals who are going to be more sensitive to heading than others. Our study provides preliminary support that women are more sensitive to these types of head impacts at the level of brain tissue microstructure,” Dr. Lipton said.
_____
Todd G. Rubin et al. MRI-defined White Matter Microstructural Alteration Associated with Soccer Heading Is More Extensive in Women than Men. Radiology, published online July 31, 2018; doi: 10.1148/radiol.2018180217
