Citation

Meehan WP, Zhang J, Mannix R, Whalen MJ. Neurosurgery 2012; 71(4): 885-891.

Affiliation

Sports Concussion Clinic, Division of Sports Medicine, Department of Orthopedics Division of Emergency Medicine, Department of Medicine, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts, USA Neuroscience Center Department of Pediatrics, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts, USA 5Brain Injury Center, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts, USA 6The Micheli Center for Sports Injury Prevention, Boston, MA.

Copyright

(Copyright © 2012, Congress of Neurological Surgeons)

DOI

10.1227/NEU.0b013e318265a439

PMID

22743360

Abstract

BACKGROUND:: While previous evidence suggests that the cognitive effects of concussions are cumulative, the effect of time interval between repeat concussions is largely unknown. OBJECTIVE:: To determine the effect of time interval between repeat concussions on the cognitive function of mice. METHODS:: We used a weight-drop model of concussion to subject anesthetized mice to 1, 3, 5, or 10 concussions, each a day apart. Additional mice were subjected to 5 concussions at varying time intervals: daily, weekly, and monthly. Morris water maze (MWM) performance was measured 24 hours, 1 month, and 1 year after final injury. RESULTS:: After 1 concussion, injured and sham-injured mice performed similarly in the MWM. As the number of concussions increased, injured mice performed worse than sham-injured mice. Mice sustaining 5 concussions either 1 day or 1 week apart performed worse than sham-injured mice. When 5 concussions were delivered at 1 month time intervals, no difference in MWM performance was observed between injured and sham-injured mice. After a 1 month recovery period, mice that sustained 5 concussions at daily and weekly time intervals continued to perform worse than sham-injured mice. One year after final injury, mice sustaining 5 concussions at a daily time interval still performed worse than sham-injured mice. CONCLUSION:: When delivered within a period of vulnerability, the cognitive effects of multiple concussions are cumulative, persistent, and may be permanent. Increasing the time interval between concussions attenuates the effects on cognition. When multiple concussions are sustained by mice daily, the effects on cognition are long-term.

Language: en