Why are Two Concussions Close in Time so Damaging?
On 11/16/14 Zachary Weil and colleagues from Ohio State University presented the answer to this question at the annual meeting of the Society for Neuroscience. Dr. Weil shared his research on how mice respond to two concussions. After the first concussion the mouse brain ramps us its use of glucose to power repair of damaged brain cells. This surge in glucose use is dependent upon the brain having normal signaling for the uptake of insulin. When the two concussions are 20 days apart the surge in glucose use has already occurred and the brain is protected. However, when the second concussion occurs just 3 days later brain signaling for uptake of insulin is disrupted, the brain becomes insulin resistant, and brain cells cannot utilize sugar. The result is lack of energy for brain repair, inflammation, and degeneration of brain cells with loss of attentional, memory, and learning abilities.
Dr. Weil says it appears that the surge in glucose utilization by the brain for self-repair appears about 6 days after a concussion. This not only means that soldiers and athletes with minor head injuries must be kept of out of action for more than a week. It also means that civilians must rest and not expose themselves to the risk of head injury for the same time frame. People with a brand new concussion should talk to their doctor about when it is wise to return to work and begin driving again. Being a driver or passenger in a car is definitely a risk factor for a second concussion.