Sex Differences in Working Memory after Mild Traumatic Brain Injury: A Functional MR Imaging Study.
OBJECTIVE
To evaluate sex differences in mild traumatic brain injury (MTBI) with working memory functional magnetic resonance (MR) imaging.


METHODS
Research ethics committee approval and patient written informed consent were obtained. Working memory brain activation patterns were assessed with functional MR imaging in 30 patients (15 consecutive men and 15 consecutive women) with MTBI and 30 control subjects (15 consecutive men and 15 consecutive women). Two imaging studies were performed in patients: the initial study, which was performed within 1 month after the injury, and a follow-up study, which was performed 6 weeks after the first study. For each participant, digit span and continuous performance testing were performed before functional MR imaging. Clinical data were analyzed by using Kruskal-Wallis, Mann-Whitney U, Wilcoxon signed rank, and Fisher exact tests. Within- and between-group differences of functional MR imaging data were analyzed with one- and two-sample t tests, respectively.


RESULTS
Among female participants, the total digit span score was lower in the MTBI group than in the control group (P = .044). In initial working memory functional MR imaging studies, hyperactivation was found in the male MTBI group and hypoactivation was found in the female MTBI group compared with control male and female groups, respectively. At the 6-week follow-up study, the female MTBI group showed persistent hypoactivation, whereas the male MTBI group showed a regression of hyperactivation at visual comparison of activation maps. The male MTBI group was also found to have a higher initial ß value than the male control group (P = .040), and there was no significant difference between the male MTBI group and the male control group (P = .221) at follow-up evaluation, which was comparable to findings on activation maps. In the female MTBI group, average ß values at both initial and follow-up studies were lower compared with those in the female control group but were not statistically significant (P = .663 and P = .191, respectively).


CONCLUSIONS
Female patients with MTBI had lower digit span scores than did female control subjects, and functional MR imaging depicted sex differences in working memory functional activation; hypoactivation with nonrecovery of activation change at follow-up studies may suggest a worse working memory outcome in female patients with MTBI.
From the Department of Diagnostic Radiology and Brain and Consciousness Research Center, Taipei Medical University Shuang-Ho Hospital, No. 291, Jhong-Jheng Road, 235 Jhonghe District, New Taipei City, Taiwan, ROC.
Hui-Ling
HL
Hsu
From the Department of Diagnostic Radiology and Brain and Consciousness Research Center, Taipei Medical University Shuang-Ho Hospital, No. 291, Jhong-Jheng Road, 235 Jhonghe District, New Taipei City, Taiwan, ROC.
David Yen-Ting
DY
Chen
From the Department of Diagnostic Radiology and Brain and Consciousness Research Center, Taipei Medical University Shuang-Ho Hospital, No. 291, Jhong-Jheng Road, 235 Jhonghe District, New Taipei City, Taiwan, ROC.
Ying-Chi
YC
Tseng
From the Department of Diagnostic Radiology and Brain and Consciousness Research Center, Taipei Medical University Shuang-Ho Hospital, No. 291, Jhong-Jheng Road, 235 Jhonghe District, New Taipei City, Taiwan, ROC.
Ying-Sheng
YS
Kuo
From the Department of Diagnostic Radiology and Brain and Consciousness Research Center, Taipei Medical University Shuang-Ho Hospital, No. 291, Jhong-Jheng Road, 235 Jhonghe District, New Taipei City, Taiwan, ROC.
Yen-Lin
YL
Huang
From the Department of Diagnostic Radiology and Brain and Consciousness Research Center, Taipei Medical University Shuang-Ho Hospital, No. 291, Jhong-Jheng Road, 235 Jhonghe District, New Taipei City, Taiwan, ROC.
Wen-Ta
WT
Chiu
From the Department of Diagnostic Radiology and Brain and Consciousness Research Center, Taipei Medical University Shuang-Ho Hospital, No. 291, Jhong-Jheng Road, 235 Jhonghe District, New Taipei City, Taiwan, ROC.
Feng-Xian
FX
Yan
From the Department of Diagnostic Radiology and Brain and Consciousness Research Center, Taipei Medical University Shuang-Ho Hospital, No. 291, Jhong-Jheng Road, 235 Jhonghe District, New Taipei City, Taiwan, ROC.
Wei-Shuan
WS
Wang
From the Department of Diagnostic Radiology and Brain and Consciousness Research Center, Taipei Medical University Shuang-Ho Hospital, No. 291, Jhong-Jheng Road, 235 Jhonghe District, New Taipei City, Taiwan, ROC.
Chi-Jen
CJ
Chen
D000293:Adolescent; D000328:Adult; D000368:Aged; D001930:Brain Injuries / Q000175:diagnosis* / Q000523:psychology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term; D008875:Middle Aged; D011446:Prospective Studies; D012737:Sex Factors; D055815:Young Adult