Chronic Effects of Boxing: Diffusion Tensor Imaging and Cognitive Findings

Abstract

We used magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) to evaluate the effects of boxing on brain structure and cognition in 10 boxers (8 retired, 2 active; mean age = 45.7 years; standard deviation [SD] = 9.71) and 9 participants (mean age = 43.44; SD = 9.11) in noncombative sports. Evans Index (maximum width of the anterior horns of the lateral ventricles/maximal width of the internal diameter of the skull) was significantly larger in the boxers (F = 4.52; p = 0.050; Cohen's f = 0.531). Word list recall was impaired in the boxers (F(1,14) = 10.70; p = 0.006; f = 0.84), whereas implicit memory measured by faster reaction time (RT) to a repeating sequence of numbers than to a random sequence was preserved (t = 2.52; p < 0.04). Fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) measured by tractography did not significantly differ between groups. However, DTI metrics were significantly correlated with declarative memory (e.g., left ventral striatum ADC with delayed recall, r = -0.74; p = 0.02) and with RT to the repeating number sequence (r = 0.70; p = 0.04) in the boxers. Years of boxing had the most consistent, negative correlations with FA, ranging from -0.65 for the right ventral striatum to -0.92 for the right cerebral peduncle. Years of boxing was negatively related to the number of words consistently recalled over trials (r = -0.74; p = 0.02), delayed recall (r = -0.83; p = 0.003), and serial RT (r = 0.66; p = 0.05). We conclude that microstructural integrity of white matter tracts is related to declarative memory and response speed in boxers and to the extent of boxing exposure. Implications for chronic traumatic encephalopathy are discussed.

A systematic review of potential long-term effects of sport-related concussion

“…However, high-frequency soccer heading (>885 per year) was associated with lower memory scores and lower FA in three regions of interest in the temporo-occipital white matter. In a study of 10 boxers (8 retired, 2 active), there were no group differences in FA between the boxers and non-contact sport controls, although DTI metrics were associated with declarative memory and reaction time 26. Using whole-brain tract-based spatial statistics analysis, 18 retired professional football players were compared with 17 healthy controls 27.…”

Systematic review on the characterization of chronic traumatic encephalopathy by MRI and MRS

“…Ten studies based on chronic TBI individuals examined a mixed gender experimental group and one did not provide information on the sex of study participants . All studies focusing on contact sports athletes investigated solely male experimental groups, and the two ex vivo studies did not provide any information on gender . Contact sports athletes included soccer players, boxers, American football players, baseball players, and wrestlers.…”

“…The age range of all studies was from school level to retirement age (13.5–74 years). Of all included in vivo studies, 22 used an age‐matched control group . All articles were published between 1994 and 2018.…”

“…From the 25 included studies, 14 used diverse MR techniques . Twenty‐one studies applied structural MRI, including T 1 ‐weighted (T 1 ‐w), T 2 ‐weighted (T 2 ‐w), fluid attenuated inversion recovery (FLAIR), susceptibility weighted imaging (SWI), and proton‐density weighted (PD‐w) imaging . Thirteen studies used diffusion MRI, specifically diffusion tensor imaging (DTI), generalized q‐sampling imaging (GQI), diffusion kurtosis imaging (DKI), and diffusion weighted imaging (DWI) .…”

“…Five articles using contact sports as the experimental group discussed diffusion MRI results . Herweh et al and Wilde et al both investigated male boxers as the experimental group .…”