Using diffusion tensor imaging (DTI), an advanced form of MRI, researchers studied the imaging results and medical records of 47 male and 22 female patients diagnosed with concussions, also known as mild traumatic brain injury (mTBI). They also studied the results of 22 control participants, 11 women and 10 men.
DTI gives scientists a measure of the movement of water molecules along axons, nerve fibers in white matter that allow communication between various areas of the brain. Healthy brains have a high value of this measurement, called fractional anisotropy (FA); in patients with brain injuries, a low FA is linked to cognitive impairment.
Researchers found male patients with concussions had much lower FA levels within a white matter tract that connects the frontal and temporal lobes of the brain, called the uncinate fasciculi (UF). They also found that FA levels in that particular area of the brain were the best predictor of recovery time, better than patient reports of their own symptoms.
“There are many factors that influence how a patient reports their symptoms, such as ulterior motives for financial gain, a desire to return to play, or post traumatic stress disorder,” says Dr. Saeed Fakhran, assistant professor of neuroradiology at the University of Pittsburgh School of Medicine. “We found that the initial symptoms were unreliable in predicting how one would recover after a concussion, but that the findings on advanced MR imaging do predict how one does after a concussion—you can't lie to the MRI magnet.”
In this study, average recovery time was 54 days, but the difference in recovery times between the sexes was significant; for women, an average of 26.3 days, and for men, 66.9 days.
It’s possible that the female hormome progesterone has something to do with the disparity. The UF connects the two areas of the brain with the most progesterone receptors, which “may suggest a protective role of progesterone in concussion, putting males at a disadvantage,” Fakhran says.
Though the role of progesterone in concussion recovery needs further study, Fakhran believes that DTI imaging should absolutely be used in standard concussion treatment.
“Before the use of DTI in concussion, we had patients who were obviously suffering significant symptoms, but simply couldn't understand why because we couldn't see the injuries in the brain with the imaging tools we commonly use,” he says.