A Neurosurgery study shows that a standard experimental model of concussion in rats causes substantial brain damage, but no behavioral changes comparable to those seen in patients with concussion. According to a Science Daily news report, the results highlight the “disconnect” between preclinical and clinical studies of concussion and also adds concerns about the potential long-term effects of repeated “subconcussive” brain trauma in humans. For the study, researchers compared injured and uninjured animals on a wide range of functional and behavioral tests.

The tests were chosen to reflect symptoms and functions similar to those used in concussion diagnosis in humans, as indicated on the Science Daily news report. The results of the study reveal that despite a rather extensive pattern of brain injury, the rats had no significant abnormalities on any of the tests on the day of the injury as well as up to 1 week after. The researchers write, “The lack of functional deficits is in sharp contrast to neuropathological findings indicating neural degeneration, astrocyte reactivity, and microglial activation.”

The Science Daily news report notes that the new experiments support the concept that significant brain damage may be present in individuals who have normal results on symptom-based assessments presently used for concussion diagnosis. The authors of the study write, “It appears that even subconcussive injury, or injury below the current clinical threshold for detection using standard measures, may have lasting neurological effects.”

The researchers stress that this short-term study in rats does not provide direct evidence of long-term changes caused by “mild” traumatic brain injury (TBI) in humans. In addition, the research team discussed the need for further research to clarify the effects of TBI over time, and to develop new models for understanding the long-term effects of repeated head trauma.

[Sources: Science Daily, Neurosurgery]