Gronwall D, Wrightson P
Lancet. 1975 Nov 22;2(7943):995-7. doi: 10.1016/s0140-6736(75)90288-3.
Twenty young adults were studied after a second concussion. The rate at which they were able to process information was reduced more than in controls who had been concussed only once, and they took longer to recover than the controls. The effects of concussion seem to be cumulative, and this has important implications for sports where concussion injury is common.
