1. Novel ImPACT Validity Indices Identify Sandbagging Regardless of ADHD Status
Angela Zachman, Lisa Manderino & John Gunstad1
1Kent State University, Kent, OH
Background
Figure 1.
Results
Athletes with ADHD did not perform significantly worse than athletes without ADHD on either of the new validity indices, F(2, 947)=0.98, p=0.91.
The current ImPACT validity indices flagged 3.4% of protocols as invalid, with a significantly higher rate of protocol invalidity in athletes with (8.0% invalid) than without (2.9% invalid) ADHD, 2(1)=6.44, p<0.05.
The rate of protocol invalidity as identified by DMTCD was significantly greater than that identified by traditional indices, 2(1)=7.40, p<0.01.
Though non-significant, a trend of higher invalidity rate using WMTCD than using traditional indices was observed, 2 (1)=3.47, p=0.06. Using WMTCD, 21.2% of protocols in the overall sample were marked as invalid.
This rate was not significantly different between athletes with (23.0%) and without (21.0%) ADHD, 2(1)=0.19, p=0.37.
Using DMTCD, 28.6% of protocols were flagged as invalid, without differences between athletes with (28.7%) and without (28.6%) ADHD.
The Immediate Post-Concussion Assessment and Cognitive Test (ImPACT) assesses neurocognitive functioning to aid diagnosis of sport-related concussion. The test includes five low-score thresholds to detect minimal effort. A person intentionally underperforming to hide future impairments post-concussion is referred to as “sandbagging”.
Individuals with Attention Deficit Hyperactivity Disorder (ADHD) often show worse ImPACT scores, even with full effort, making it difficult to determine baseline validity.
Two additional validity indices have been developed to differentiate sandbagging from genuine effort poor performance as would be expected in athletes with ADHD – Word Memory Total Correct Distractors (WMTCD) and Design Memory Total Correct Distractors (DMTCD).
The present study examines whether these novel validity indices better differentiate a genuine poor baseline from a sandbagging baseline.
Figure 2.
Conclusions
Both novel validity indices on the ImPACT identified an equal number of student-athletes as having sub-optimal performance, regardless of ADHD status.
However, DMTCD identified more baseline profiles as invalid overall, raising the possibility that it may be more sensitive to sandbagging.
The addition of the WMTCD and DMTCD may aid in differentiating athletes performing at their best from those with naturally-occurring low baselines.
Methods
This study examines three seasons of baseline ImPACT scores from 950 student-athletes (age=19.5±1.44y; 9.2% ADHD).
The traditional five ImPACT validity indices and the two novel indices (WMTCD and DMTCT) were compared in student-athletes with and without reported histories of ADHD.
Chi-squared tests determined whether rates of protocol invalidity were the same in student-athletes with and without ADHD.