Neurometabolic Changes in the Acute Phase after Sports Concussions Correlate with Symptom Severity

Abstract

Sports concussion is a major problem that affects thousands of people in North America every year. Despite negative neuroimaging findings, many athletes display neurophysiological alterations and post-concussion symptoms such as headaches and sensitivity to light and noise. It is suspected that neurometabolic changes may underlie these changes. In this study we investigated the effects of sports concussion on brain metabolism using (1)H-MR spectroscopy by comparing a group of 12 non-concussed athletes with a group of 12 concussed athletes of the same age (mean 22.5 years) and education (mean 16 years). All athletes were scanned 1-6 days post-concussion in a 3T Siemens MRI, and were administered a symptom scale to evaluate post-concussion symptomatology. Participants also completed a neuropsychological test battery to assess verbal memory, visual memory, information processing speed, and reaction time, and no group differences were detected relative to controls. Concussed athletes showed a higher number of symptoms than non-concussed athletes, and they also showed a significant decrease in glutamate in the primary motor cortex (M1), as well as significant decreases in N-acetylaspartate in the prefrontal and primary motor cortices. No changes were observed in the hippocampus. Furthermore, the metabolic changes in M1 correlated with self-reported symptom severity despite equivalent neuropsychological performance. These results confirm cortical neurometabolic changes in the acute post-concussion phase, and demonstrate for the first time a correlation between subjective self-reported symptoms and objective physical changes that may be related to increased vulnerability of the concussed brain.

Neuro-Metabolite Changes in a Single Season of University Ice Hockey Using Magnetic Resonance Spectroscopy

“…The significant decrease in NAA, a marker of viable neurons, from pre- to postseason was observed regardless of sex or whether the player had an in-season concussion. This result does not directly corroborate the findings of previous researchers, which have demonstrated a transient decrease in NAA after concussion, followed by a recovery in NAA ( 8 , 33 ). The results of the present study suggest a persistent decrease in NAA that is still present at the end of the playing season, as opposed to a transient decrease followed by a recovery in NAA levels.…”

Neuro-Metabolite Changes in a Single Season of University Ice Hockey Using Magnetic Resonance Spectroscopy

“…The significant decrease in NAA, a marker of viable neurons, from pre- to postseason was observed regardless of sex or whether the player had an in-season concussion. This result does not directly corroborate the findings of previous researchers, which have demonstrated a transient decrease in NAA after concussion, followed by a recovery in NAA ( 8 , 33 ). The results of the present study suggest a persistent decrease in NAA that is still present at the end of the playing season, as opposed to a transient decrease followed by a recovery in NAA levels.…”

A Systematic Review of Proton Magnetic Resonance Spectroscopy Findings in Sport-Related Concussion

“…52 In the other study, a significant decrease in NAA was observed in the dorsolateral prefrontal cortex (DLPFC) and in the M1 in addition to significant decreases in Glu in M1. 50 The findings of decreases in NAA, in the above-mentioned acute studies, were consistent with the acute findings in other MRS studies that examined both acute and subacute phases. 51,53,57 Repeated or follow-up MRS was conducted in five of the 11 identified studies.…”

Low Prefrontal GABA Levels Are Associated With Poor Cognitive Functions in Professional Boxers

“…It is noteworthy that there were no statistical differences of the Glx/Cr ratio between the Boxers and CON groups. This result is partially consistent with previous findings which indicate that glutamate levels initially decrease during the acute stage and gradually return to the normal range in the chronic phase, at the time of 6 months after the exposure to rmTBI (Henry et al, 2010). Given that the duration of exposure to boxing-related rmTBI was more than 2 years for the participants recruited in the current study, it is plausible that alterations in Glx levels might have been present in the Boxer group prior to the study, and then normalized at the time of assessment.…”

Neuro-Metabolite Changes in a Single Season of University Ice Hockey Using Magnetic Resonance Spectroscopy

“…The significant decrease in NAA, a marker of viable neurons, from pre- to postseason was observed regardless of sex or whether the player had an in-season concussion. This result does not directly corroborate the findings of previous researchers, which have demonstrated a transient decrease in NAA after concussion, followed by a recovery in NAA ( 8 , 33 ). The results of the present study suggest a persistent decrease in NAA that is still present at the end of the playing season, as opposed to a transient decrease followed by a recovery in NAA levels.…”

A Systematic Review of Proton Magnetic Resonance Spectroscopy Findings in Sport-Related Concussion

“…52 In the other study, a significant decrease in NAA was observed in the dorsolateral prefrontal cortex (DLPFC) and in the M1 in addition to significant decreases in Glu in M1. 50 The findings of decreases in NAA, in the above-mentioned acute studies, were consistent with the acute findings in other MRS studies that examined both acute and subacute phases. 51,53,57 Repeated or follow-up MRS was conducted in five of the 11 identified studies.…”

Low Prefrontal GABA Levels Are Associated With Poor Cognitive Functions in Professional Boxers

“…It is noteworthy that there were no statistical differences of the Glx/Cr ratio between the Boxers and CON groups. This result is partially consistent with previous findings which indicate that glutamate levels initially decrease during the acute stage and gradually return to the normal range in the chronic phase, at the time of 6 months after the exposure to rmTBI (Henry et al, 2010). Given that the duration of exposure to boxing-related rmTBI was more than 2 years for the participants recruited in the current study, it is plausible that alterations in Glx levels might have been present in the Boxer group prior to the study, and then normalized at the time of assessment.…”

Neuro-Metabolite Changes in a Single Season of University Ice Hockey Using Magnetic Resonance Spectroscopy

“…The significant decrease in NAA, a marker of viable neurons, from pre- to postseason was observed regardless of sex or whether the player had an in-season concussion. This result does not directly corroborate the findings of previous researchers, which have demonstrated a transient decrease in NAA after concussion, followed by a recovery in NAA ( 8 , 33 ). The results of the present study suggest a persistent decrease in NAA that is still present at the end of the playing season, as opposed to a transient decrease followed by a recovery in NAA levels.…”

A Systematic Review of Proton Magnetic Resonance Spectroscopy Findings in Sport-Related Concussion

“…52 In the other study, a significant decrease in NAA was observed in the dorsolateral prefrontal cortex (DLPFC) and in the M1 in addition to significant decreases in Glu in M1. 50 The findings of decreases in NAA, in the above-mentioned acute studies, were consistent with the acute findings in other MRS studies that examined both acute and subacute phases. 51,53,57 Repeated or follow-up MRS was conducted in five of the 11 identified studies.…”

Low Prefrontal GABA Levels Are Associated With Poor Cognitive Functions in Professional Boxers

“…It is noteworthy that there were no statistical differences of the Glx/Cr ratio between the Boxers and CON groups. This result is partially consistent with previous findings which indicate that glutamate levels initially decrease during the acute stage and gradually return to the normal range in the chronic phase, at the time of 6 months after the exposure to rmTBI (Henry et al, 2010). Given that the duration of exposure to boxing-related rmTBI was more than 2 years for the participants recruited in the current study, it is plausible that alterations in Glx levels might have been present in the Boxer group prior to the study, and then normalized at the time of assessment.…”