In recent years there has been a dramatic increase in the use of neuropsychological tests to evaluate the effects of concussion in competitive athletes and assist in return to play decisions. In this chapter, we focus on one factor that can limit the sensitivity of neuropsychological tests to concussion--practice effects. The data we present suggests that the HVLT-R, Trails B, Stroop 2, and SDMT are most susceptible to practice effects upon repeated administration. Nonetheless, we show that even for these tests, a majority of control athletes do not show significant practice effects after several administrations when the reliability of the measures and regression to the mean are controlled for. Still, the fact that a significant minority of athletes show practice effects on these tests should serve as a note of caution for interpreting these commonly used clinical neuropsychological tests postconcussion. In contrast to these test indices, the Stroop 1 and Trails A showed little evidence for practice effects even when administered several times. Because the Stroop I also showed evidence for sensitivity to concussion, it emerged as perhaps the best test in terms of combined resistance to practice effects and concussion sensitivity. In terms of return to play decisions, because we found that a negligible number of controls displayed evidence for reliable decline from baseline on all six test indices, the data we present in this chapter strongly suggest that when concussed athletes continue to show performance reliably below baseline performance at one-week postconcussion on any of the noted test indices, great caution should be exercised in recommending return to play. Additionally, any athlete who is still reliably below baseline on two of the test indices at one-week postconcussion should not return to play because residual persisting cognitive effects from the concussion are highly likely. Future work can extend this research by using larger samples, better matching on overall cognitive ability.
