Imaging of neuroinflammation due to repetitive head injury in currently active kickboxers

Gilles N Stormezand,Remco J Renken,Joukje Van Der Naalt,Jacoba M Spikman,David Vállez García,Sandra E Rakers,Chris W J Van Der Weijden,Rudi A J O Dierckx,Anouk Van Der Hoorn,Janine Doorduin,Berry P H Kremer

doi:10.1007/s00259-022-05715-x

Abstract

PurposeChronic traumatic encephalopathy refers to a neurodegenerative disease resulting from repetitive head injury of participants in contact sports. Similar to other neurodegenerative diseases, neuroinflammation is thought to play a role in the onset and progression of the disease. Limited knowledge is available regarding the neuroinflammatory consequences of repetitive head injury in currently active contact sports athletes. PET imaging of the 18-kDa translocator protein (TSPO) allows quantification of microglial activation in vivo, a marker of neuroinflammation.MethodsEleven rank A kickboxers and 11 age-matched controls underwent TSPO PET using [11C]-PK11195, anatomical MRI, diffusion tensor imaging, and neuropsychological testing. Relevant imaging parameters were derived and correlated with the outcomes of the neuropsychological testing.ResultsOn a group level, no statistically significant differences were detected in non-displaceable binding potential (BPND) using PET. Individually, 3 kickboxers showed increased BPNDs in widespread regions of the brain without a correlation with other modalities. Increased FA was observed in the superior corona radiata bilaterally. DTI parameters in other regions did not differ between groups.ConclusionDespite negative results on a group level, individual results suggest that neuroinflammation may be present as a consequence of repetitive head injury in active kickboxers. Future studies using a longitudinal design may determine whether the observed TSPO upregulation is related to the future development of neuropsychiatric symptoms.

Highlights

Chronic traumatic encephalopathy (CTE) refers to a neurodegenerative disease resulting from repetitive head injury in participants of contact sports [1]
Due to technical problems related to the PET scanning procedure (PET reconstruction problem (n = 1), failure to place arterial lining (n = 3)), 11 kickboxers and 11 controls remained for the final analysis
The current study fails to provide evidence of translocator protein (TSPO) upregulation in currently active kickboxers on a group level, but the widespread increased binding of [11C]-PK11195 in approximately 1 out of 4 kickboxers suggests that neuroinflammation may be present as a consequence of repetitive head injury

Summary

Introduction

Chronic traumatic encephalopathy (CTE) refers to a neurodegenerative disease resulting from repetitive head injury in participants of contact sports [1]. It can manifest with neuropsychiatric symptoms which may be affective. This article is part of the Topical Collection on Neurology (depression), behavioral (aggression), and/or cognitive (concentration, memory, or executive impairments). If these latter symptoms are severe, this can be qualified as dementia. The clinical presentation is correlated with different pathological stages (I–IV) [2]. The onset of the clinical syndrome is after the athletes have ended their careers [7]

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