The Professional Fighters Brain Health Study has generated much useful data. The study, conducted out of the Cleveland Clinic Luo Ruvo Center for Brain Health in Las Vegas has been compiling data since 2011 giving insight into the tolls professional fighting takes on athletes’ brains.
The latest data, published in Neurotrauma Reports, canvasses brain volume reduction reviewing data from both professional boxers and mixed martial artists and comparing the data across lower, mid range and heavier weight classes.
In the recent study, titled Effect of Weight Class on Regional Brain Volume, Cognition, and Other Neuropsychiatric Outcomes among Professional Fighters, the authors followed fifty-three boxers and 103 MMA ﬁghter. The fighters underwent volumetric magnetic resonance imaging (MRI) and neuropsychological testing. When comparing the data, broken down into light weight, middleweight, and heavyweight fighters, the authors noted that while heavier fighters had greater annual reduction of regional brain volume lower weight class fighters “suffered greater reductions in regional brain volume on a per-ﬁght basis“.
The authors noted further research is needed on this finding but hypothesized that the tolls of extreme weight cutting could be playing a roll with the following comments
In certain regions (left thalamus in boxers, right putamen in MMA ﬁghters), lightweight ﬁghters demonstrated greater yearly reductions in volume on a perﬁght basis. The widespread practice of rapid weight loss through dehydration and caloric restriction among professional ﬁghters to meet weight class requirements may be more common in lighter-weight-class ﬁghters and underlie their increased susceptibility to brain injury with increasing number of ofﬁcial ﬁghts. Although ﬁghters may begin re-feeding and re-hydration immediately after weigh-in, previous studies have found dehydration to be highly prevalent among ﬁghters at the time of competition.
Dehydration secondary to rapid cutting of weight may worsen TBI-induced neurotrauma, potentially contributing to the observed association of lighter weightclass with worse outcomes on a per-ﬁght basis. This effect would likely only persist during the acute period following dehydration, and as such would only alter the impact of TBIs sustained during professional bouts. It has been proposed that dehydration-induced changes in brain morphology may alter mechanical cushioning and strain mitigation provided in part by cerebrospinal ﬂuid within the subarachnoid space and lateral ventricles.
Although the exact mechanisms are unclear, the present ﬁndings are consistent with this hypothesis and highlight the need for future research into the inﬂuence of weight-cutting on the long-term brain health of professional ﬁghters. It should also be considered that heavyweights may have more comorbidities (i.e. diabetes, metabolic syndrome, etc.) potentially exacerbating neurodegenerative processes through pro-inﬂammatory pathways. This might contribute to greater yearly decrements in heavyweights despite the greater volume of strikes absorbed by lightweights on a per-ﬁght basis and the possible exacerbations from effects of weight-cutting. Future work is required to elucidate these complex relationships
The full abstract reads as follows:
Traumatic brain injury (TBI) is a common source of functional impairment among athletes, military personnel, and the general population. Professional ﬁghters in both boxing and mixed martial arts (MMA) are at particular risk for repetitive TBI and may provide valuable insight into both the pathophysiology of TBI and its consequences. Currently, effects of ﬁghter weight class on brain volumetrics (regional and total) and functional outcomes are unknown. Fifty-three boxers and 103 MMA ﬁghters participating in the Professional Fighters Brain Health Study (PRBHS) underwent volumetric magnetic resonance imaging (MRI) and neuropsychological testing. Fighters were divided into lightweight (£139.9 lb), middleweight (140.0–178.5 lb), andheavyweight (>178.5 lb). Compared with lightweight ﬁghters, heavyweights displayed greater yearly reductions in regional brain volume (boxers: bilateral thalami; MMA:leftthalamus, right putamen) and functional performance (boxers: processing speed, simple and choice reaction; MMA:TrailsA and B tests). Lightweights suffered greater reductions in regional brain volume on a per-ﬁght basis(boxers: left thalamus;MMA:rightputamen).Heavyweight ﬁghtersbore greater yearly burden of regional brain volume and functional decrements, possibly related to differing ﬁght dynamics and force of strikes in this division. Lightweights demonstrated greater volumetric decrements on a per-ﬁght basis. Although more research is needed, greater per-ﬁght decrements in lightweights may be related to practices of weightcutting, which may increase vulnerability to neurodegeneration post-TBI. Observed decrements associated with weight class may result in progressive impairments in ﬁghter performance, suggesting interventions mitigating the burden of TBI in professional ﬁghters may both improve brain health and increase professional longevity