Quantifying head impacts and neurocognitive performance in collegiate boxers.

Head impacts and neurocognition were quantified in 27 intercollegiate male boxers engaged in two, two-minute sparring rounds. Head impacts were measured using Instrumented Boxing Headgear (IBH). Pre and post-sparring neurocognitive performance was compared using two computerized neuropsychological test batteries (CNTs): Immediate Post-concussion Assessment and Cognitive Testing (ImPACT™) and Automated Neuropsychological Assessment Metrics - Military Battery (ANAM4® MIL). An average of 27.63 ± 17.87 impacts above the 9.6 g IBH threshold were recorded per boxer, with average peak linear acceleration of 23.48 ± 15.20 g and average peak rotational acceleration of 1761.40 ± 1064.34 rad/s2. Small, but measurable declines in delayed memory and improvement in response time from pre- to post-bout were noted. Number of impacts and concussion history predicted degraded memory performance. This is a unique quantification of head impacts in collegiate boxing, which were similar in frequency and location, but lower in magnitude as compared to amateur boxing. Improved understanding of impact kinematics may enhance safety in boxing and other contact sports. Subtle post-bout decrements in delayed memory performance and mild improvement in response time reinforce prior research and provide evidence of congruence in our two CNT assessments, which may facilitate comparisons of outcomes across settings utilizing these tests.

Permethrin exposure from fabric-treated military uniforms under different wear-time scenarios.

The objective of the project was to ascertain whether urinary biomarkers of permethrin exposure are detected after wearing post-tailored, fabric-treated military uniforms under two different wear-time exposure scenarios. Study A occurred over 3.5 days and involved six participants wearing treated uniforms continuously for 30-32 h. Urine collection occurred at scheduled time points before, during, and after wearing the uniform. Study B, conducted over 19 days, included 11 participants wearing treated uniforms for 3 consecutive days, 8 h each day (with urine collection before, during, and after wear). Urinary biomarkers of permethrin (3-phenoxybenzoic acid (3PBA), cis- 2,2-(dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (cDCCA), trans- 2,2-(dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (tDCCA)) were detected during and after wear. Biomarker detection generally occurred over the 10- to 12-h period after putting on the uniform and subsided 24 h following uniform removal (in both Study A and B scenarios). Those wearing permethrin-treated uniforms under the longer wear-time scenario (Study A) excreted significantly higher cumulative mean levels compared with those in Study B (3.29 times higher for 3PBA and 2.23 times higher for the sum of c/tDCCA (P≤0.001)). Findings suggest that wearing permethrin-treated clothing does increase absorbed, internal dose levels of permethrin above population levels and is significantly related to wear-time duration.

Effects of 2 adenosine antagonists, quercetin and caffeine, on vigilance and mood.

Quercetin, a phenolic flavonoid found in small quantities in some fruits and vegetables, is an adenosine receptor antagonist in vitro marketed as a dietary supplement for purported caffeine-like effects. A double-blind, placebo-controlled, between-subjects study was conducted to compare the behavioral effects of quercetin to a central adenosine receptor antagonist, caffeine. Fifty-seven volunteers received either 2000 mg of quercetin dihydrate (a dose estimated based on in vitro receptor binding to be equivalent in potency to 200 mg of caffeine), placebo, or 200 mg of caffeine. One hour later, a 45-minute visual vigilance task was administered. The Profile of Mood States questionnaire was completed before treatment and immediately after vigilance testing. On the vigilance task, caffeine increased the number of stimuli detected (P < 0.02) and decreased the reaction time (P = 0.001). Caffeine increased self-reported vigor and reduced fatigue and total mood disturbance Profile of Mood States scores compared with placebo. Quercetin did not significantly alter any parameter, but values were typically intermediate between caffeine and placebo on those tests affected by caffeine. Quercetin is unlikely to have any effects when consumed by humans in quantities present in the diet or in dietary supplements. Caffeine (200 mg) administration resulted in the expected effects on vigilance and mood.

A double-blind, placebo-controlled test of 2 d of calorie deprivation: effects on cognition, activity, sleep, and interstitial glucose concentrations.

BACKGROUND: Anecdotal information and limited research suggest that short-term caloric deprivation adversely affects cognition. However, this issue has not been studied using double-blind, placebo-controlled procedures, because the formulation of a calorie-deficient feeding regimen identical to one with calories is impossible using ordinary foods. Therefore, test meals varying in caloric content, but indistinguishable in sensory characteristics, were formulated using hydrocolloid-based gels as the principal structural component. OBJECTIVE: The purpose of this study was to examine the effects of 2 d of near-total caloric deprivation on cognitive function, satiety, activity, sleep, and glucose concentrations in a controlled environment. DESIGN: A double-blind, placebo-controlled crossover study of caloric deprivation was conduced in a controlled environment for 48 h. Cognitive function in 27 healthy young subjects was assessed repeatedly with standardized tests of vigilance, reaction time, learning, memory, logical reasoning, mood, and satiety. Wrist-worn monitors were used to assess ambulatory vigilance, activity, and sleep. Interstitial glucose concentrations were assessed continuously with a minimally invasive monitor. RESULTS: When the subjects received the near calorie-free diets, mean calorie consumption totaled 1311 kJ (313 kcal) over the testing period. During the fully fed treatment sessions, the subjects consumed a mean of 9612 kJ/d (2294 kcal/d), which matched their individual, daily energy requirements. Satiety and interstitial glucose concentrations were lower during the calorie-deprived diet (P < 0.001) than during the fully fed diet. There were no detectable effects of calorie deprivation on any aspect of cognitive performance, ambulatory vigilance, activity, or sleep. The mood states assessed, including fatigue, were not affected by calorie deprivation. CONCLUSIONS: Cognitive performance, activity, sleep, and mood are not adversely affected in healthy humans by 2 d of calorie-deprivation when the subjects and investigators are unaware of the calorie content of the treatments.

Hydration effects on cognitive performance during military tasks in temperate and cold environments.

Body water deficits or hypohydration (HYP) may degrade cognitive performance during heat exposure and perhaps temperate conditions. Cold exposure often induces HYP, but the combined effects of cold and HYP on cognitive performance are unknown. This study investigated whether HYP degrades cognitive performance during cold exposure and if physical exercise could mitigate any cold-induced performance decline. On four occasions, eight volunteers completed one hour of militarily-relevant cognitive testing: 30 min of simulated sentry duty/marksmanship, 20 min of a visual vigilance task, a self-report workload assessment, and a mood questionnaire. Testing was conducted in a cold (2 degrees C) or temperate (20 degrees C) environment before and after cycle ergometer (60 min at 60% of VO(2peak)) exercise. Each trial was preceded by 3 h of passive heat stress (45 degrees C) in the early morning with (euhydration, EUH) or without (hypohydration, HYP; 3% body mass) fluid replacement followed by prolonged recovery. HYP did not alter any cognitive, psychomotor, or self-report parameter in either environment before or after exercise. Cold exposure increased (p<0.05) target detection latency in the sentry duty task, adversely affected mood and workload ratings, but had no impact on any other cognitive or psychomotor measure. After completing the exercise bout, there were modest improvements in friend-foe discrimination and total response latency in the sentry duty task, but not on any other performance measures. Moderate HYP had no effect on cognitive and psychomotor performance in either environment, cold exposure produced equivocal effects, and aerobic exercise improved some aspects of military task performance.