Objective Accurate concussion management relies on the integrity of baseline and after injury assessments to reflect actual cognitive abilities. This study assessed performance differences in optimal versus malingering conditions, and evaluated the ability of embedded effort indicators in the Axon Sports Computerised Cognitive Assessment Tool (CCAT) to detect suboptimal effort.

Design Within-subject, randomised, with Optimal and Feigned impairment conditions.

Setting Cognitive testing with the CCAT was completed at a university clinic.

Subjects A healthy adult sample aged between 16 and 30 years.

Intervention Subjects were randomly assigned to one of two conditions: (1) Practice-Optimal-Feigned or (2) Practice-Feigned-Optimal. All subjects were instructed to perform to the best of their abilities during the Practice and Optimal test sessions, and were instructed to feign a malingering condition where they were seeking compensation for a head injury in the Feigned test session.

Outcome Measurements Mean reaction times and accuracy scores on each of the four CCAT tasks for the Optimal versus Feigned conditions. Overall test validity and individual integrity criteria on the CCAT for assessment of the embedded effort indictors.

Results Subjects displayed reduced reaction times and decreased accuracy during the Feigned condition versus the Optimal condition. The CCAT had 100% sensitivity identifying intentional suboptimal effort in this sample, with 93% specificity.

Conclusions Identifiable changes in cognitive performance occurred when subjects feigned impairment during cognitive testing. Embedded effort indicators in the CCAT detected this suboptimal effort with exception sensitivity. Acceptable results on CCAT baseline testing reflect tests where subjects were not malingering.

Competing interests Drs Maruff and Cromer are full time employees of CogState, Ltd, manufacturer of the Axon Sports CCAT.