Memory in repeat sports-related concussive injury and single-impact traumatic brain injury

ABSTRACT

Background: Repeat sports-related concussive/subconcussive injury (RC/SCI) is related to memory impairment.

Objective & Methods: We sought to determine memory differences between persons with RC/SCI, moderate-to-severe single-impact traumatic brain injury (SI-TBI), and healthy controls. MRI scans from a subsample of participants with SI-TBI were used to identify the neuroanatomical correlates of observed memory process differences between the brain injury groups.

Results: Both brain injury groups evidenced worse learning and recall in contrast to controls, although SI-TBI group had poorer memory than the RC/SCI group. Regarding memory process differences, in contrast to controls, the SI-TBI group evidenced difficulties with encoding, consolidation, and retrieval, while the RC/SCI group showed deficits in consolidation and retrieval. Delayed recall was predicted by encoding, with consolidation as a secondary predictor in the SI-TBI group. In the RC/SCI group, delayed recall was only predicted by consolidation. MRI data showed that the consolidation index we used mapped onto hippocampal atrophy.

Conclusions: RC/SCI is primarily associated with consolidation deficits, which differs from SI-TBI. Given the role of the hippocampus in memory consolidation and the fact that hyperphosphorylated tau tends to accumulate in the medial temporal lobe in RC/SCI, consolidation deficits may be a cognitive marker of chronic traumatic encephalopathy in athletes.

KEYWORDS:

• Concussion
• traumatic brain injury
• memory
• sport

Author Contributions

Study concept and design: M.J.W.; data acquisition and analysis: M.J.W., D.F.K., K.G., D.J.H., P.M.V., D.A.H., W.D.L., M.M.M., E.S.L.; drafting manuscript and figures: M.J.W., M.M.M., E.S.L.; review and editing the manuscript: M.J.W., M.M.M., E.S.L., P.Y.L., D.J.H., D.F.K., K.G., R.C.C., P.M.V., D.A.H., W.D.L., C.W., R.S., J.M.F.

Competing of Interests

We declare no competing of interests.

Data availability

Data from this study will be made available upon request to M.J.W.

Additional information

Funding

This research was supported by National Operating Committee on Standards for Athletic Equipment, the National Center for Research Resources (M01 RR 19975), the National Institutes of Health (NS049471 & NS02089), the California State Neurotrauma Initiative, and the Los Angeles Biomedical Research Institute.