Prevalence of Invalid Performance on Baseline Testing for Sport-Related Concussion by Age and Validity Indicator

Importance

Estimated base rates of invalid performance on baseline testing (base rates of failure) for the management of sport-related concussion range from 6.1% to 40.0%, depending on the validity indicator used. The instability of this key measure represents a challenge in the clinical interpretation of test results that could undermine the utility of baseline testing.

Objectives

To determine the prevalence of invalid performance on baseline testing and to assess whether the prevalence varies as a function of age and validity indicator.

Design, Setting, and Participants

This retrospective, cross-sectional study included data collected between January 1, 2012, and December 31, 2016, from a clinical referral center in the Midwestern United States. Participants included 7897 consecutively tested, equivalently proportioned male and female athletes aged 10 to 21 years, who completed baseline neurocognitive testing for the purpose of concussion management.

Interventions

Baseline assessment was conducted with the Immediate Postconcussion Assessment and Cognitive Testing (ImPACT), a computerized neurocognitive test designed for assessment of concussion.

Main Outcomes and Measures

Base rates of failure on published ImPACT validity indicators were compared within and across age groups. Hypotheses were developed after data collection but prior to analyses.

Results

Of the 7897 study participants, 4086 (51.7%) were male, mean (SD) age was 14.71 (1.78) years, 7820 (99.0%) were primarily English speaking, and the mean (SD) educational level was 8.79 (1.68) years. The base rate of failure ranged from 6.4% to 47.6% across individual indicators. Most of the sample (55.7%) failed at least 1 of 4 validity indicators. The base rate of failure varied considerably across age groups (117 of 140 [83.6%] for those aged 10 years to 14 of 48 [29.2%] for those aged 21 years), representing a risk ratio of 2.86 (95% CI, 2.60-3.16; P < .001).

Conclusions and Relevance

The results for base rate of failure were surprisingly high overall and varied widely depending on the specific validity indicator and the age of the examinee. The strong age association, with 3 of 4 participants aged 10 to 12 years failing validity indicators, suggests that the clinical interpretation and utility of baseline testing in this age group is questionable. These findings underscore the need for close scrutiny of performance validity indicators on baseline testing across age groups.

High-fat feeding does not induce an autophagic or apoptotic phenotype in female rat skeletal muscle

Apoptosis and autophagy are critical in normal skeletal muscle homeostasis; however, dysregulation can lead to muscle atrophy and dysfunction. Lipotoxicity and/or lipid accumulation may promote apoptosis, as well as directly or indirectly influence autophagic signaling. Therefore, the purpose of this study was to examine the effect of a 16-week high-fat diet on morphological, apoptotic, and autophagic indices in oxidative and glycolytic skeletal muscle of female rats. High-fat feeding resulted in increased fat pad mass, altered glucose tolerance, and lower muscle pAKT levels, as well as lipid accumulation and reactive oxygen species generation in soleus muscle; however, muscle weights, fiber type-specific cross-sectional area, and fiber type distribution were not affected. Moreover, DNA fragmentation and LC3 lipidation as well as several apoptotic (ARC, Bax, Bid, tBid, Hsp70, pBcl-2) and autophagic (ATG7, ATG4B, Beclin 1, BNIP3, p70 s6k, cathepsin activity) indices were not altered in soleus or plantaris following high-fat diet. Interestingly, soleus muscle displayed small increases in caspase-3, caspase-8, and caspase-9 activity, as well as higher ATG12-5 and p62 protein, while both soleus and plantaris muscle showed dramatically reduced Bcl-2 and X-linked inhibitor of apoptosis protein (XIAP) levels. In conclusion, this work demonstrates that 16 weeks of high-fat feeding does not affect tissue morphology or induce a global autophagic or apoptotic phenotype in skeletal muscle of female rats. However, high-fat feeding selectively influenced a number of apoptotic and autophagic indices which could have implications during periods of enhanced muscle stress.

A maternal diet high in saturated fat impairs offspring hippocampal function in a sex-specific manner

While a maternal diet high in saturated fat is likely to affect foetal brain development, whether the effects are the same for male and female offspring is unclear. As a result, we randomly assigned female, Sprague-Dawley rats to either a control, or high-fat diet (HFD; 45% of calories from saturated fat) for 10 weeks. A range of biometrics were collected, and hippocampal function was assessed at both the tissue level (by measuring synaptic plasticity) and at the behavioural level (using the Morris water maze; MWM). Subsequently, a subset of animals was bred and remained on their respective diets throughout gestation and lactation. On post-natal day 21, offspring were weaned and placed onto the control diet; biometrics and spatial learning and memory were then assessed at both adolescence and young adulthood. Although the HFD led to changes in the maternal generation consistent with an obese phenotype, no impairments were noted at the level of hippocampal synaptic plasticity, or MWM performance. Unexpectedly, among the offspring, a sexually dimorphic effect upon MWM performance became apparent. In particular, adolescent male offspring displayed a greater latency to reach the platform during training trials and spent less time in the target quadrant during the probe test; notably, when re-examined during young adulthood, the performance deficit was no longer present. Overall, our work suggests the existence of sexual dimorphism with regard to how a maternal HFD affects hippocampal-dependent function in the offspring brain.

An updated review of the prevalence of invalid performance on the Immediate Post-Concussion and Cognitive Testing (ImPACT)

Objective: Performance validity assessment is an important component of concussion baseline testing and Immediate Post-Concussion and Cognitive Testing (ImPACT) is the most commonly used test in this setting. A review of invalid performance on ImPACT was published in 2017, focusing largely on the default embedded validity indicator (Default EVI) provided within the test. There has since been a proliferation in research evaluating the classification accuracy of the Default EVI against independently developed, alternative ImPACT-based EVIs, necessitating an updated review. The purpose of this study was to provide an up-to-date review of the prevalence of invalid performance on ImPACT and to examine the relative effectiveness of ImPACT-based EVIs. Method: Literature related to the prevalence of invalid performance on ImPACT and the effectiveness of ImPACT-based EVIs, published between January 2000 and May 2020, was critically reviewed. Results: A total of 23 studies reported prevalence of invalid performance at baseline testing using ImPACT. Six percent of baseline assessments were found to be invalid by the ImPACT's Default EVI, and between 22.31% and 34.99% were flagged by alternative EVIs. Six studies assessed the effectiveness of ImPACT-based EVIs, with the Default EVI correctly identifying experimental malingerers only 60% of the time. Alternative ImPACT-based EVIs identified between 73% and 100% of experimental malingerers. Conclusions: The ImPACT's Default EVI is not sufficiently sensitive, and clinicians should consider alternative indicators when assessing invalid performance. Accordingly, the base rate of invalid performance in athletes at baseline testing is likely well above the 6% previously reported.

This will only take a minute: Time cutoffs are superior to accuracy cutoffs on the forced choice recognition trial of the Hopkins Verbal Learning Test - Revised

OBJECTIVE

This study was designed to evaluate the classification accuracy of the recently introduced forced-choice recognition trial to the Hopkins Verbal Learning Test - Revised (FCR_HVLT-R) as a performance validity test (PVT) in a clinical sample. Time-to-completion (T2C) for FCR_HVLT-R was also examined.

METHOD

Forty-three students were assigned to either the control or the experimental malingering (expMAL) condition. Archival data were collected from 52 adults clinically referred for neuropsychological assessment. Invalid performance was defined using expMAL status, two free-standing PVTs and two validity composites.

RESULTS

Among students, FCR_HVLT-R ≤11 or T2C ≥45 seconds was specific (0.86-0.93) to invalid performance. Among patients, an FCR_HVLT-R ≤11 was specific (0.94-1.00), but relatively insensitive (0.38-0.60) to non-credible responding0. T2C ≥35 s produced notably higher sensitivity (0.71-0.89), but variable specificity (0.83-0.96). The T2C achieved superior overall correct classification (81-86%) compared to the accuracy score (68-77%). The FCR_HVLT-R provided incremental utility in performance validity assessment compared to previously introduced validity cutoffs on Recognition Discrimination.

CONCLUSIONS

Combined with T2C, the FCR_HVLT-R has the potential to function as a quick, inexpensive and effective embedded PVT. The time-cutoff effectively attenuated the low ceiling of the accuracy scores, increasing sensitivity by 19%. Replication in larger and more geographically and demographically diverse samples is needed before the FCR_HVLT-R can be endorsed for routine clinical application.