MR Spectroscopy Findings in Retired Professional Rugby League Players

Abstract

The aim of this study was to examine brain neurometabolite concentrations in retired rugby league players who had a history of numerous self-reported concussions. Participants were 16 retired professional rugby league players (ages 30-45 years) with an extensive history of concussion and participation in contact sports, and 16 age- and education-matched controls who had no history of neurotrauma or participation in contact sports. All completed a clinical interview, psychological and cognitive testing, and magnetic resonance spectroscopy (MRS) investigation. MRS voxels were placed in posterior cingulate grey matter and parietal white matter. Neurometabolite concentrations were quantified using LCModel. It was hypothesized that retired athletes would differ on N-acetyl aspartate, myo-inositol, choline, glutamate, and glutathione. Retired players had significantly lower concentrations of grey matter glutathione (p=0.02, d=0.91). They did not significantly differ in concentrations of other neurometabolites. There were no significant differences between groups on measures of depression, anxiety, or cognitive functioning. The retired athletes reported significantly greater alcohol use (p<0.01; Cohen's d=1.49), and they had worse manual dexterity using their non-dominant hand (p=0.03; d=1.08). These preliminary findings suggest that MRS might be modestly sensitive to biochemical differences in athletes after their athletic careers have ended in the absence of clinical differences in cognitive performance and self-reported psychological functioning.

History of Sport-Related Concussion and Long-Term Clinical Cognitive Health Outcomes in Retired Athletes: A Systematic Review

“…* In 7 studies, retired rugby players were investigated. 13,15,17,22,31,33,54 Participants in the remaining studies included boxers (n ¼ 3) 29,57,58 and soccer athletes (n ¼ 4), 26,32,38,56 whereas other authors examined a combination of former professional and amateur athletes, including university and high school football and hockey athletes (n ¼ 12). † Of the 46 studies, 33 included a control group, ‡ and 13 did not.…”

“…Language. Eight groups 16,17,21,23,24,39,43,49 reviewed language tests, including tests of naming, speech production, and verbal fluency. The Boston Naming Test was used in 4 (50%) studies.…”

“…39,49 Esopenko et al 16 used the Phonemic Word List Generation (verbal phonemic fluency test) and found no differences between retired contact-sport athletes and control participants. The Controlled Oral Word Association Test was used in 5 investigations, 17,23,24,43,49 and no differences were identified between the retired athlete and control groups. Overall, our review showed mixed evidence of language deficits in retired athletes.…”

“…Psychomotor Function. Psychomotor function was assessed by 6 groups, 13,17,22,31,45,56 with 4 sets of researchers 13,17,22,45 reporting decreases in retired athletes compared with control participants. Pearce et al 13 used the Cambridge Neuropsychological Test Automated Battery-Visuomotor Reaction Time subtest and found that retired rugby players reacted more slowly to the stimulus than the control group (P , .01).…”

“…Pearce et al 13 used the Cambridge Neuropsychological Test Automated Battery-Visuomotor Reaction Time subtest and found that retired rugby players reacted more slowly to the stimulus than the control group (P , .01). McMillan et al 22 observed that retired rugby players had decreased fine motor coordination in the dominant hand on the Grooved Pegboard test, a measure of visual-motor coordination, whereas Gardner et al 17 reported worse scores for the nondominant hand (P ¼ .03). Pearce et al 45 assessed fine motor control and learned that reaction time (both reaction to stimulus and movement time on the O'Connor Finger Dexterity Test) was better in the healthy control group than in the retired elite and amateur Australian football players (P ¼ .003).…”