MILD HEAD-INJURY AND SPEED OF INFORMATION-PROCESSING - A PROSPECTIVE-STUDY OF PROFESSIONAL RUGBY LEAGUE PLAYERS

The sensitivity of several short tests of speed of information process ing to the effects of mild head injury in rugby league football was in vestigated. The measures used were the Symbol Digit Modalities Test, t he Digit Symbol Substitution Test, and the Speed of Comprehension Test . Two studies were conducted, the first to examine the effect of pract ice, the second to determine sensitivity to cognitive impairment immed iately following injury. The first study established alternate form eq uivalence and demonstrated that performance on the Speed of Comprehens ion and Digit Symbol Substitution tests improved with practice, wherea s the Symbol Digit Modalities test remained stable. A second study of 10 players who subsequently sustained mild head injuries showed that m easures of speed of information processing were sensitive to impairmen t in the postacute phase, whereas an untimed task of word recognition (Spot-the-Word) was not. Speed of Comprehension was more sensitive to postinjury impairment than either the Digit Symbol Substitution or Sym bol Digit Modalities tests. A repeated baseline assessment before inju ry using the higher score to reflect a player's potential, allowed mea surement of impaired performance on sensitive tests.