The headaches came back during that break, but they were less frequent and easier to tolerate. The forgetfulness was still alarming, but she knew she had access to help. The tranquility of her new life, with whole days spent in her dimly lit, quiet apartment, had eased her symptoms. But she also knew that they could flare up under stress and overstimulation. On one such occasion, last June, her baby had a severe fever and Becky rushed her to the emergency room. Forms and questions rang out and raspy beeps blared from the monitors as the baby whimpered on the bed. The lights above were brashly fluorescent, the worst kind for someone with brain damage. In the emergency room, Becky felt pressure build up behind her temples and forgot a few simple words. “I need to know my…” she dropped for a few seconds. “Choices.”
Almost everything we know that concussion and neurodegenerative diseases come from studying male brains. But some of the research we have, mostly on the brains of athletes, suggests that women may be more vulnerable to concussions than men. Concussions displace the brain’s gelatinous neuron mass, disrupting the circuits that affect mood, function, thinking and more. Men generally have more muscular necks that better absorb the acceleration of the head. There are also anatomical differences between male and female axons. Women’s axons — nerve fibers that unfold between neurons to form communication networks — have a generally more slender architecture that could shear more easily during trauma. Successive concussions can rupture them, releasing tangles of tau protein in the brain. But the differences are more than mechanical.
When Ramesh Raghupathi, a professor of neurobiology and anatomy at Drexel University College of Medicine, began studying concussions in female rats, he immediately noticed differences from males. The cellular changes were similar, but functionally the rats had different outcomes: the females experienced more intense anxiety and depression. “It had more to do with the circuitry and neurochemistry of the female brain compared to the male brain,” he says. “You can’t ignore the role of sex hormones.”
In a 2014 study, researchers found that women of childbearing age experienced worse post-concussive symptoms than postmenopausal women or women using hormonal birth control, especially when the concussion occurred during the luteal phase of the menstrual cycle (after ovulation, before menstruation begins). ). Progesterone levels are high during this time, and one theory is that progesterone disruption, perhaps caused by damage to the pituitary gland, can have a particularly harsh impact on neurons. In other words, when a victim is in her menstrual cycle at the time of the impact, it can have a significant effect on the outcome of her traumatic brain injury.
A study published last year analyzed female athletes during the immediate aftermath of concussions. Researchers measured levels of progesterone and noted menstrual phases at the time of injury. Their results were consistent with the association of progesterone disruption and worse outcomes, although more data is needed to understand why. (An estimated 31 to 50 percent of transgender people experience intimate partner violence, with higher numbers for transgender women, but no study has analyzed the impact of brain injury in this group.)
“So much money goes into researching concussions in sports that those protocols and documents shape the way concussions are generally thought of,” said Stephen Casper, a neurology historian at Clarkson University. “There is no money to be made from studying intimate partner violence.” When it comes to chronic neurodegenerative diseases like CTE, even less is known about what women can face after decades of abuse. A slight acceleration or tremor of the brain that does not register as a concussion, if repeated often enough, can cause a cascading, dementia-like disease process that continues for years after the trauma has subsided and is only discovered by postmortem examination.
At the VA-BU-CLF Brain Bank in Boston, the world’s first CTE-targeted brain repository, Ann McKee, the director, has collected about 1,250 copies. Her findings have helped change the way football is played and have helped move hundreds of millions of dollars into compensation for victims, bringing the neurological dangers of contact sports clearly into the public consciousness. But 14 years after the bank was founded, almost all of its specimens are still male. Female brains, McKee says, are hard to come by, especially from women like Becky. “If you have a situation of interpersonal violence, you need to get permission from the next of kin to get a brain donation,” she says. Domestic violence creates an embarrassment that can be difficult for families to confront, and if the next of kin are the abuser, there’s virtually no chance.