Premorbid intellectual functioning impacts baseline concussion screening performance

Journal of the International Neuropsychological Society. 2018 Nov;

24(s1):55.

Ritchie, K. A., Hoelzle, J., Nelson, L. D. and Mccrea, M. A..

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Abstract:

Objective: Intellectual ability influences neuropsychological test performance. This study investigates the rate at which healthy individuals of below average, average, and above average intellectual functioning obtain impaired scores on the Standardized Assessment of Concussion (SAC; McCrea et al., 2000) and Immediate Post-Concussion and Cognitive Testing (ImPACT, 2013). Participants and Methods: An archival sample of pre-season, baseline test data from healthy amateur athletes [N = 1988, M age = 17.82(1.90)] was utilized that included the SAC, ImPACT, and the Wechsler Test of Adult Reading (WTAR; Wechsler, 2001). Participants were stratified into groups based on WTAR performance. Chi-square tests for independence determined whether rates of obtaining one or more impaired score (i.e. scores below the 5th percentile) varied among groups. Results: Pearson Chi-square tests indicated a significant association between estimated IQ group and observed frequency of impaired scores on both the SAC [÷2 = 36.38, p < .05, Cramer’s V = 0.14] and ImPACT [÷2 = 25.63, p < .05, Cramer’s V = 0.14]. On the SAC, participants with below average estimated IQ obtained impaired scores at a higher rate than anticipated, while those with above average estimated IQ obtained impaired scores at a lower rate than would be expected. On ImPACT, participants with average estimated IQ obtained impaired scores at a higher rate than would be expected, while individuals with above average estimated IQ obtained impaired scores at a significantly lower rate than anticipated. Conclusions: Although concussion screening instruments are designed to detect cognitive impairment due to injury, this study suggests that intellectual ability meaningfully influences performance on these instruments at baseline. These findings are relevant to consider when using these instruments for clinical decision-making as intellectual ability may influence the likelihood of obtaining impaired scores, rather than the injury characteristics.

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