Ill, not mischievous As early as the late 19th century, the medical community had discovered hyperactivity, unpredictable behavior, and an inability to concentrate in people who had suffered injuries to the brain or the central nervous system.
早在十九世紀末期，醫學界就已發現，一些受過腦傷、中樞神經受損的病患，有過動、衝動、容易分心的現象。