title: A two-factor theory for concussion assessment using ImPACT: memory and speed.
abstract: We present the initial validation of a two-factor structure of Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) using ImPACT composite scores and document the reliability and validity of this factor structure. Factor analyses were conducted for baseline (N = 21,537) and post-concussion (N = 560) data, yielding "Memory" (Verbal and Visual) and "Speed" (Visual Motor Speed and Reaction Time) Factors; inclusion of Total Symptom Scores resulted in a third discrete factor. Speed and Memory z-scores were calculated, and test-retest reliability (using intra-class correlation coefficients) at 1 month (0.88/0.81), 1 year (0.85/0.75), and 2 years (0.76/0.74) were higher than published data using Composite scores. Speed and Memory scores yielded 89% sensitivity and 70% specificity, which was higher than composites (80%/62%) and comparable with subscales (91%/69%). This emergent two-factor structure has improved test-retest reliability with no loss of sensitivity/specificity and may improve understanding and interpretability of ImPACT test results.
authors.affiliation: Saint Joseph's University, Philadelphia, PA, USA.
authors.forename: Philip
authors.initials: P
authors.lastname: Schatz
authors.forename: Arthur
authors.initials: A
authors.lastname: Maerlender
mesh_terms: D000293:Adolescent; D056352:Athletes / Q000523:psychology; D001924:Brain Concussion / Q000175:diagnosis* / Q000523:psychology*; D016022:Case-Control Studies; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory; D009483:Neuropsychological Tests; D011930:Reaction Time; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: ImPACT; concussion; neurocognitive testing; reliability; validity