Purpose: The Immediate Post-Concussion Assessment and Cognitive Test (ImPACT) assesses neurocognitive functioning in diagnosing sport-concussion. It includes low-score thresholds to detect poor effort or intentional underperformance to hide post-concussion impairments (“sandbagging”). However, individuals with Attention Deficit Hyperactivity Disorder (ADHD) often show lower ImPACT scores regardless of effort. Two previously proposed validity indices may better differentiate sandbagging from genuine poor performance.
Procedure: This study examines three seasons of baseline scores from 950 student-athletes. Rates of protocol invalidity produced by the traditional ImPACT indices and the external indices (Word-Memory Total Correct Distractors [WMTCD] and Design-Memory Total Correct Distractors [DMTCD]) were compared in athletes with and without ADHD using chi-squared tests.
Results: Athletes with ADHD did not perform worse than athletes without ADHD on either external index, F(2, 947)=0.98, p=0.91. The ImPACT validity indices flagged 3.4% of protocols as invalid, with a higher rate in athletes with (8.0% invalid) than without (2.9% invalid) ADHD, c2(1)=6.44, p2(1)=7.40, p2 (1)=3.47, p=0.06, though was not significantly different between athletes with (23.0%) and without (21.0%) ADHD, c2(1)=0.19, p=0.37.
Conclusions: External validity indices identified sub-optimal performance equally, suggesting they may aid in differentiating athletes performing at their best from those with naturally-occurring low baselines.
Dr. John Gunstad
The ImPACT scores Word Memory Correct-Distractors and Design Memory Correct-Distractors have been proposed to better differentiate sandbagging, or intentional under-performance to hide post-concussive impairments, from genuine-effort performances. They were examined as validity indices in athletes with and without ADHD, who tend to score lower regardless of effort. Rates of protocol invalidity were compared chi-squared tests. The traditional validity indices flagged 3.4% of protocols as invalid, with a higher rate in athletes with ADHD. Protocol invalidity identified by DMTCD was significantly greater than that identified by traditional indices, though not significantly different between athletes with and without ADHD. Both identified sub-optimal performance equally in the groups, suggesting they may aid in differentiating athletes performing at their best from those with naturally-occurring low baselines.
Zachman, A., Manderino, L., & Gunstad, J. (2017). Novel ImPACT Validity Indices Identify Sandbagging Regardless of ADHD Status. https://oaks.kent.edu/node/5521
Zachman, Angela, Lisa Manderino, and John Gunstad. 2017. “Novel ImPACT Validity Indices Identify Sandbagging Regardless of ADHD Status”. https://oaks.kent.edu/node/5521.
Zachman, A., L. Manderino, and J. Gunstad. Novel ImPACT Validity Indices Identify Sandbagging Regardless of ADHD Status. 21 Mar. 2017, https://oaks.kent.edu/node/5521.