Beyond Measures of Central Tendency: Novel Methods to Examine Sex Differences in Neuropsychological Performance Following Sports-Related Concussion in Collegiate Athletes

Abstract

Objective:The purpose of this study was to examine sex differences in neuropsychological functioning after sports-related concussion using several approaches to assess cognition: mean performance, number of impaired scores, and intraindividual variability (IIV).Method:In the study, 152 concussed college athletes were administered a battery of neuropsychological tests, on average, 10 days post-concussion (SD = 12.75; Mdn = 4 days; Range = 0–72 days). Mean performance was evaluated across 18 individual neuropsychological variables, and the total number of impaired test scores (>1.5 SD below the mean) was calculated for each athlete. Two measures of IIV were also computed: an intraindividual standard deviation (ISD) score and a maximum discrepancy (MD) score.Results:Analyses of covariance revealed that, compared with males, females had significantly more impaired scores and showed greater variability on both IIV indices (ISD and MD scores) after adjusting for time since injury and post-concussive symptoms. In contrast, no significant effects of sex were found when examining mean neuropsychological performance.Conclusion:Although females and males demonstrated similar mean performance following concussion, females exhibited a greater level of cognitive impairment and larger inconsistencies in cognitive performance than males. These results suggest that evaluating cognitive indices beyond mean neuropsychological scores may provide valuable information when determining the extent of post-concussion cognitive dysfunction.

Loss of Consciousness is Associated with Elevated Cognitive Intra-Individual Variability Following Sports-Related Concussion

“…Until recently, cognitive performance following SRC has primarily been evaluated using measures of central tendency (i.e., mean performance). However, as measures of acrosstest IIV, or cognitive dispersion, become more readily utilized in other clinical populations (Bangen et al, 2019;Gleason et al, 2018;Hilborn et al, 2009;Holtzer et al, 2008;Jones et al, 2018), researchers have started applying these novel metrics to SRC samples (Merritt et al, 2019;Rabinowitz & Arnett, 2013). Our current results add to this burgeoning SRC-IIV literature by establishing a potentially important relationship between the presence of LOC and increased cognitive variability acutely following injury.…”

“…All athletes were administered a comprehensive neuropsychological assessment that encompassed both computerized and paper-and-pencil tests, spanning the domains of attention, processing speed/reaction time, executive functioning, and memory (see Merritt et al, 2019 In total, 18 variables were derived from the above measures and were used to generate the IIV indices, our primary outcomes of interest. Prior to computing the IIV indices, the 18 neuropsychological variables were converted from raw scores to standard scores using sex-specific normative data generated from a sample of college athletes evaluated at baseline (Merritt et al, 2017).…”

“…Converting all raw scores to standard scores ensured that all variables could be interpreted on the same scale and in a uniform direction (i.e., higher standard score values reflect better performance). After verifying that all raw neuropsychological variables were converted to standard scores, two IIV indices were computed using similar procedures as described in Merritt et al (2019)-an intraindividual standard deviation (ISD) score and a range, or maximum discrepancy (MD), score. Briefly, the standard deviation of the 18 standard scores was used to compute the ISD score for each athlete, and the difference between each athlete's highest and lowest score represented the MD score.…”

“…Furthermore, neuropsychologists routinely administer a wide range of tests during a single evaluation and utilize this information clinically when making diagnostic recommendations; thus, cognitive dispersion scores may be easily generated from a standard battery of tests. Although few studies within the SRC literature have examined cognitive dispersion, the small body of existing research indicates that IIV may be an important marker of cognitive dysfunction in this unique population and offer information above and beyond that of mean performance (Merritt et al, 2019;Rabinowitz & Arnett, 2013).…”

Presenting features of female collegiate sports-related concussion in South Africa: a descriptive analysis

“…However, comparative studies also report small female collegiate SRC cohort sizes. [13,18,[20][21][22][23] The small sample size is in spite of the multiyear time period under consideration in this study. This should not be construed as an indication of overall low female SRC incidence.…”