Longitudinal Changes in Regional Brain Volumes and Cognition of Professional Fighters With Traumatic Encephalopathy Syndrome.

BACKGROUND AND OBJECTIVES: Due to current limitations in diagnosing chronic traumatic encephalopathy (CTE) clinically, traumatic encephalopathy syndrome (TES) has been proposed as the clinical presentation of suspected CTE. This study aimed to determine whether there was an association between a clinical diagnosis of TES and subsequent temporal decline in cognitive or MRI volumetric measures. METHODS: This was a secondary analysis of the Professional Athletes Brain Health Study (PABHS), inclusive of active and retired professional fighters older than 34 years. All athletes were adjudicated as TES positive (TES+) or TES negative (TES-) based on the 2021 clinical criteria. General linear mixed models were used to compare MRI regional brain volumes and cognitive performance between groups. RESULTS: A total of 130 fighters met inclusion criteria for consensus conference. Of them, 52 fighters (40%) were adjudicated as TES+. Athletes with a TES+ diagnosis were older and had significantly lower education. Statistically significant interactions and between-group total mean differences were found in all MRI volumetric measurements among the TES+ group compared with those among the TES- group. The rate of volumetric change indicated a significantly greater increase for lateral (estimate = 5,196.65; 95% CI = 2642.65, 7750.66) and inferior lateral ventricles (estimate = 354.28; 95% CI = 159.90, 548.66) and a decrease for the hippocampus (estimate = -385.04, 95% CI = -580.47, -189.62), subcortical gray matter (estimate = -4,641.08; 95% CI = -6783.98, -2498.18), total gray matter (estimate = -26492.00; 95% CI = -50402.00, -2582.32), and posterior corpus callosum (estimate = -147.98; 95% CI = -222.33, -73.62). Likewise, the rate of cognitive decline was significantly greater for reaction time (estimate = 56.31; 95% CI = 26.17, 86.45) and other standardized cognitive scores in the TES+ group. DISCUSSION: The 2021 TES criteria clearly distinguishes group differences in the longitudinal presentation of volumetric loss in select brain regions and cognitive decline among professional fighters 35 years and older. This study suggests that a TES diagnosis may be useful in professional sports beyond football, such as boxing and mixed martial arts. These findings further suggest that the application of TES criteria may be valuable clinically in predicting cognitive decline.

Traumatic encephalopathy syndrome: application of new criteria to a cohort exposed to repetitive head impacts.

OBJECTIVE: To examine the characteristics of those who fulfil the recent National Institute of Neurological Disease and Stroke (NINDS) Consensus Diagnostic Criteria for Traumatic Encephalopathy Syndrome (TES) and test whether they show differences in MRI-based regional brain volumes, cognitive domains, and certain plasma biomarkers. METHODS: Professional fighters 35 years of age or older and/or retired were included. Participants were categorised as either having TES (TES+) or not (non-TES). TES+ participants were further subtyped by their cognitive profile. Multiple linear regression models were used to compare MRI-based regional brain volumes, cognitive performance, plasma tau and neurofilament light levels between TES- and TES+ groups. RESULTS: 176 participants (110 boxers and 66 MMA) were included in the analysis. 72 (41%)/176 were categorised as having TES, the likelihood of TES increasing with age. TES+ participants tended to be boxers, started fighting at a younger age, had more professional fights and knocked out more frequently. The TES+ group had lower regional brain volumes including both grey and white matter structures. TES+ also had lower scores on simple and choice reaction time, psychomotor speed and Trails A . CONCLUSION: The new TES criteria does distinguish a group of fighters with differences in regional brain volumes and reduced cognitive function. Our findings support the use of the NINDS criteria for TES in further research of the long-term effects of repetitive head impacts.

Deficits in comprehension of speech acts after TBI: The role of theory of mind and executive function.

Theory of mind (ToM) is critical to effective communication following traumatic brain injury (TBI) however, whether impairments are specific to social cognition, or reflective of executive demands is unclear. This study examined whether ToM impairments are predicted by executive function difficulties using everyday conversation tasks. Twenty-five individuals with severe-TBI were compared to 25 healthy controls on low- and high-ToM tasks across four conditions: (1) low cognitive load, (2) high flexibility, (3) high working memory (WM) and (4) high inhibition. TBI individuals were impaired on high-ToM tasks in the WM condition. When the WM demands of the task were controlled, the impairments were no longer apparent. TBI individuals were not impaired on high-ToM tasks in the inhibition and flexibility conditions, suggesting these tasks may not have been sufficiently demanding of ToM abilities. The results suggest that ToM impairments in everyday communication may arise due to WM demands, in individuals with TBI.

Cognitive factors underpinning poor expressive communication skills after traumatic brain injury: theory of mind or executive function?

OBJECTIVE: The ability to see things from another's perspective, that is, have a theory of mind (ToM), is essential to effective communication. So too is the ability to regulate verbal output, that is, to exercise executive control. People with traumatic brain injuries (TBIs) have impaired communication abilities, but the extent to which this reflects ToM versus executive dysfunction is unclear. This study explored the relative contributions of executive abilities, specifically flexibility and inhibition and ToM abilities in language production post-TBI. METHOD: Twenty-five adults (18 males: mean age of 48.2 years, SD = 12.0 years) with moderate to severe TBI (posttraumatic amnesia = 69.2, SD = 54.6 days) and 28 noninjured adults (19 males: mean age 49.0, SD = 12.2 years) completed three sets of communication tasks with low executive demands, high flexibility, and high inhibition demands. Within each, parallel versions had low or high ToM requirements. RESULTS: For low executive and high flexibility tasks, scores on the high ToM versions were predicted by scores on the low ToM versions, suggesting that poor performance was explained by the executive demands the parallel tasks had in common. The exception was the high inhibition task. In this case, speakers with TBI had differential difficulty with the high ToM version, that is, they had specific difficulty inhibiting self-referential thoughts in order to cater for another's perspective. CONCLUSION: We found problems with inhibiting the self-perspective accords with descriptive accounts of the egocentric nature of some communication patterns following TBI, which points to potential targets for remediation.

Impaired emotional contagion following severe traumatic brain injury.

Empathy deficits are widely-documented in individuals after severe traumatic brain injury (TBI). This study examined the relationship between empathy deficits and psychophysiological responsivity in adults with TBI to determine if impaired responsivity is ameliorated through repeated emotional stimulus presentations. Nineteen TBI participants (13 males; 41 years) and 25 control participants (14 males; 31 years) viewed five repetitions of six 2-min film clip segments containing pleasant, unpleasant, and neutral content. Facial muscle responses (zygomaticus and corrugator), tonic heart rate (HR) and skin conductance level (SCL) were recorded. Mean responses for each viewing period were compared to a pre-experiment 2-min resting baseline period. Self-reported emotional empathy was also assessed. TBI participants demonstrated identical EMG response patterns to controls, i.e. an initial large facial response to both pleasant and unpleasant films, followed by habituation over repetitions for pleasant films, and sustained response to unpleasant films. Additionally, an increase in both arousal and HR deceleration to stimulus repetitions was found, which was larger for TBI participants. Compared to controls, TBI participants self-reported lower emotional empathy, and had lower resting arousal, and these measures were positively correlated. Results are consistent with TBI producing impairments in emotional empathy and responsivity. While some normalisation of physiological arousal appeared with repeated stimulus presentations, this came at the cost of greater attentional effort.

Assessing social cognition and pragmatic language in adolescents with traumatic brain injuries.

Traumatic brain injuries (TBI) in children and adolescents can impair social cognition and communication skills but there are few assessment tools suitable for adolescents. The Awareness of Social Inference Test (TASIT) uses professionally enacted audiovisual vignettes of everyday conversational exchanges and is a valid measure of social perception disorders in adults. This study examined its utility for assessing impairments in social cognition in a group of 16 adolescents with TBI, compared to a group of 16 typically developing (TD) adolescents. Adolescents with TBI were, on average, no different to their TD peers on TASIT 1 (emotion recognition) and TASIT 3 (recognizing lies and sarcasm when provided with additional cues) but performed more poorly on TASIT 2 which required them to interpret sarcastic and sincere conversational exchanges with few cues other than the demeanor of the speakers. Within the TBI group, poor performance on TASIT correlated to both relative and self-reported communication difficulties at home. It also correlated with IQ, face recognition and severity of injury as indexed by duration of post-traumatic amnesia. Overall, this study suggests TASIT is a valid measure for adolescents although it raised questions as to how effective normative data is for comparing performance in social cognition during childhood and adolescence.