Letter

I had some concerns I feel are necessary to share with readers regarding a story in which I was quoted (“Mild TBI Can Have Long-Term Effects,” March 2009, p. 1). There is no international consensus on the long-standing clinical problem of defining “concussion” or “mild traumatic brain injury,” making it challenging to do research and compare and analyze studies. Also, one cannot “lump” and compare studies of persons with single concussions or MTBI with studies on people who have had multiple concussions—they are two very distinct populations.