Bucking the emerging belief that females are more vulnerable to concussion, a new study finds that irrespective of the severity of initial concussive symptoms, girls and women who've suffered mild traumatic brain injury recover faster than do boys and men.
In a group of 47 men with concussions who were tracked, tested and brain-scanned immediately after their diagnoses and followed until they were fully recovered, the average "time to symptom resolution" was 66.9 days (with a median of 41 days). Among the 22 female patients with concussions, the average recovery time was 26.3 days (with a median of 21 days).
While subjects in the study ranged from 10 to 50 years old, the average age of male and female subjects did not differ significantly, and neither did the severity of their earliest post-injury symptoms. The principal difference between the genders was the speed with which they were able to shake off such problems as headaches, dizziness, irritability or concentration or memory difficulties.
The gender difference that appears to play a crucial role in concussion recovery lies at the heart of the brain, in the uncinate fasciculus, a hook-shaped bundle of neural cables that connect the brain's primitive limbic system with its seat of higher reasoning, the frontal lobes. In female subjects who sustained blows to the head, a brain-scanning technique called diffusion tensor imaging revealed that the uncinate fasciculus was far less likely to be stretched, torn and frayed than was the case in male subjects with concussions.
Male or female, a subject whose uncinate fasciculus showed clear signs of shearing was in for a longer recovery time, the researchers found. But even with concussive symptoms just as extreme, brain-injured females were less likely than their injured male peers to show such damage.
The researchers also compared the integrity of the concussion victims' uncinate fasciculi with that of a control group of healthy subjects: In concussed males, that bundle of connective tissue was dramatically more torn and frayed than it was in healthy controls; comparing that tissue's integrity in healthy female control subjects with concussed women, they saw little differerence.
Past research has suggested that when women suffer concussions, they initially report more symptoms than do men. But scientists have long suspected that progesterone, a female reproductive hormone believed to protect the brain during stroke or injury, should make women more resilient after concussions than are men. Observational studies that have relied on subjective reports have yielded inconsistent results on which sex fared better.
The current study, published in the journal Radiology, appears to be among the first to offer an objective measure of concussion injury that bypasses social expectations and subjective reports. It zeroes in on the most promising means of gauging such injury -- by diffusion tensor imaging. And it give physicians trying to predict a patient's prognosis a specific place in the brain -- the uncinate fasciculus -- to look for injury. While researchers have been focusing increasingly on white matter as a measure of concussion injury, there are many such tracts to assess.