Males take longer to recover after concussion than females, according to a study of mild traumatic brain injury (mTBI) published in the September issue of Radiology.

The study used diffusion tensor imaging (DTI) as a bias-free way to predict concussion outcome and assess recovery time without relying on subjective measures from the patient.

Approximately 15 percent of the more than 17 million Americans who suffer a mTBI each year will have symptoms persist beyond three months, however standard MRI and CT images can often appear normal, explained lead author Saeed Fakhran, MD, and colleagues from the University of Pittsburgh School of Medicine.

DTI, on the other hand, can measure the fractional anisotropy (FA) of water molecules moving along axons. Low FA—indicating more random water movement—has been associated with cognitive impairment in patients with brain injury.

Fakhran and colleagues’ study included 69 patients (47 male) diagnosed with mTBI between 2006 and 2013. More than two-thirds of the males and nearly half of the females in the study were injured playing a sport. A control group featuring 21 healthy volunteers (10 male) also was included. All participants received DTI of the brain as well as computerized neurocognitive testing.

DTI scan results showed that mTBI patients had abnormalities within the uncinate fasciculi (UF)—a white matter tract connecting the frontal and temporal lobes—and that males had significantly decreased FA values in the UF compared with females.

In fact, UF FA value was a stronger predictor of recovery time than initial symptom severity based on neurocognitive testing, according to the authors. Male gender was also directly correlated with an increase in recovery time; average recovery time for male patients was 66.9 days compared with 26.4 days for females.

“The correlation of UF injury with increased time to recovery in patients with mTBI, and an overall pattern of more pronounced UF injury in males, suggests that the degree of injury to the UF may be a potential explanation for previously observed sex differences in outcome following mTBI,” wrote Fakhran and colleagues. “It is significant that injury to the UF not only correlated with outcome but that the injury was different between males and females.”

The authors added that an understanding of patterns of white matter injury and the use of UF FA values could help physicians better define the clinical relevance of a given injury.