A Season of American Football Is Not Associated with Changes in Plasma Tau

American football athletes are routinely exposed to sub-concussive impacts over the course of the season. This study sought to examine the effect of a season of American football on plasma tau, a potential marker of axonal damage. Nineteen National Collegiate Athletic Association (NCAA) football athletes underwent serial blood sampling over the course of the 2014–2015 season at those times in which the number and magnitude of head impacts likely changed. Non-contact sport controls (NCAA men's swim athletes; n = 19) provided a single plasma sample for comparison. No significant differences were observed between control swim athletes and football athletes following a period of non-contact (p = 0.569) or a period of contact (p = 0.076). Football athletes categorized as starters (n = 11) had higher tau concentrations than non-starters (n = 8) following a period of non-contact (p = 0.039) and contact (p = 0.036), but not higher than swimmers (p = 1.000 and p = 1.000, respectively). No difference was noted over the course of the season in football athletes, irrespective of starter status. Despite routine head impacts common to the sport of American football, no changes were observed over the course of the season in football athletes, irrespective of starter status. Further, no difference was observed between football athletes and non-contact control swim athletes following a period of non-contact or contact. These data suggest that plasma tau is not sensitive enough to detect damage associated with repetitive sub-concussive impacts sustained by collegiate–level football athletes

Effect of Docosahexaenoic Acid on a Biomarker of Head Trauma in American Football

PURPOSE: American football athletes are exposed to subconcussive impacts over the course of the season resulting in elevations in serum neurofilament light (NFL), a biomarker of axonal injury. Docosahexaenoic acid (DHA) has been reported to reduce axonal trauma associated with traumatic brain injury in rodent models. However, the optimal dose in American football athletes is unknown. This study examined the effect of differing doses of DHA on serum NFL over the course of a season of American football. METHODS: In a randomized, double-blind, placebo-controlled, parallel design, 81 National Collegiate Athletic Association Division I American football athletes were assigned to ingest either 2, 4, 6 g·d−1 of DHA or placebo. Blood was sampled at specific times over the course of 189 d, coincident with changes in intensity, hours of contact, and likely changes in head impacts. Standardized magnitude-based inference was used to define outcomes. RESULTS: DHA supplementation increased plasma DHA in a dose-dependent manner (2 g·d⁻¹: mean difference from baseline; ±90% CL; 2 g·d⁻¹: 1.3; ±0.6; 4 g·d⁻¹: 1.6; ±0.7%; 6 g·d⁻¹: 1.6; ±0.7%; 6 g·d⁻¹) versus nonstarters (1398 ± 581 pg·mL⁻¹; P = 0.024). Irrespective of dose, supplemental DHA likely attenuated serum NFL coincident with increases in serum NFL by likely small and moderate magnitude (effect size = 0.4–0.7). CONCLUSIONS: Findings from this study, the first large-scale study examining potential prophylactic use of DHA in American football athletes, include identification of optimal dose of DHA, suggesting a neuroprotective effect of DHA supplementation

Serum Neurofilament Light in American Football Athletes over the Course of a Season

Despite being underreported, American football boasts the highest incidence of concussion among all team sports, likely due to exposure to head impacts that vary in number and magnitude over the season. This study compared a biological marker of head trauma in American football athletes with non-contact sport athletes and examined changes over the course of a season. Baseline serum neurofilament light polypeptide (NFL) was measured after 9 weeks of no contact and compared with a non-contact sport. Serum NFL was then measured over the course of the entire season at eight time-points coincident with expected changes in likelihood of increased head impacts. Data were compared between starters (n = 11) and non-starters (n = 9). Compared with non-starters (mean ± standard deviation) (7.30 ± 3.57 pg•mL-1) and controls (6.75 ± 1.68 pg•mL-1), serum NFL in starters (8.45 ± 5.90 pg•mL-1) was higher at baseline (mean difference; ±90% confidence interval) (1.69; ± 1.96 pg•mL-1 and 1.15; ± 1.4 pg•mL-1, respectively). Over the course of the season, an increase (effect size [ES] = 1.8; p < 0.001) was observed post-camp relative to baseline (1.52 ± 1.18 pg•mL-1), which remained elevated until conference play, when a second increase was observed (ES = 2.6; p = 0.008) over baseline (4.82 ± 2.64 pg•mL-1). A lack of change in non-starters resulted in substantial differences between starters and non-starters over the course of the season. These data suggest that a season of collegiate American football is associated with elevations in serum NFL, which is indicative of axonal injury, as a result of head impacts

Desire and Dread from the Nucleus Accumbens: Cortical Glutamate and Subcortical GABA Differentially Generate Motivation and Hedonic Impact in the Rat

Background: GABAergic signals to the nucleus accumbens (NAc) shell arise from predominantly subcortical sources whereas glutamatergic signals arise mainly from cortical-related sources. Here we contrasted GABAergic and glutamatergic generation of hedonics versus motivation processes, as a proxy for comparing subcortical and cortical controls of emotion. Local disruptions of either signals in medial shell of NAc generate intense motivated behaviors corresponding to desire and/or dread, along a rostrocaudal gradient. GABA or glutamate disruptions in rostral shell generate appetitive motivation whereas disruptions in caudal shell elicit fearful motivation. However, GABA and glutamate signals in NAc differ in important ways, despite the similarity of their rostrocaudal motivation gradients. Methodology/Principal Findings: Microinjections of a GABAA agonist (muscimol), or of a glutamate AMPA antagonist (DNQX) in medial shell of rats were assessed for generation of hedonic ‘‘liking’ ’ or ‘‘disliking’ ’ by measuring orofacial affective reactions to sucrose-quinine taste. Motivation generation was independently assessed measuring effects on eating versus natural defensive behaviors. For GABAergic microinjections, we found that the desire-dread motivation gradient was mirrored by an equivalent hedonic gradient that amplified affective taste ‘‘liking’ ’ (at rostral sites) versus ‘‘disliking’ ’ (at caudal sites). However, manipulation of glutamatergic signals completely failed to alter pleasure-displeasure reactions to sensory hedonic impact, despite producing a strong rostrocaudal gradient of motivation

Coordination Cost and Super-Efficiency in Teamwork: The Role of Communication, Psychological States, Cardiovascular Responses, and Brain Rhythms

To advance knowledge on the psychophysiological markers of “coordination cost” in team settings, we explored differences in meta-communication patterns (i.e., silence, speaking, listening, and overlap), perceived psychological states (i.e., core affect, attention, efficacy beliefs), heart rate variability (i.e., RMSSD), and brain rhythms (i.e., alpha, beta and theta absolute power) across three studies involving 48 male dyads (Mage = 21.30; SD = 2.03). Skilled participants cooperatively played three consecutive FIFA-17 (Xbox) games in a dyad against the computer, or competed against the computer in a solo condition and a dyad condition. We observed that playing in a team, in contrast to playing alone, was associated with higher alpha peak and global efficiency in the brain and, at the same time, led to an increase in focused attention as evidenced by participants’ higher theta activity in the frontal lobe. Moreover, we observed that overtime participants’ brain dynamics moved towards a state of “neural-efficiency” or “flow”, characterized by increased theta and beta activity in the frontal lobe, and high alpha activity across the whole brain. Our findings advance the literature by demonstrating that (1) the notion of coordination cost can be captured at the neural level in the initial stages of team development; (2) by decreasing the costs of switching between tasks, teamwork increases both individuals’ attentional focus and global neural efficiency; and (3) communication dynamics become more proficient and individuals’ brain patterns change towards neural efficiency over time, likely due to team learning and decreases in intra-team conflict