It is not just the kind of head injury that matters, but the kind of head—even in children.

Martin et al 1 (pp) found that those children and adolescents who suffer a mild traumatic brain injury (mTBI) who were anxious before the mTBI do worse. They had almost 50% more symptoms at baseline and took almost twice as long as those without preinjury anxiety to return to school. The authors minimised the risk that reporting bias might explain the effect by examining preinjury medical records to confirm prior treatment for anxiety, and took into account the effect of confounders. Given that they studied fairly large numbers with only modest …