Concussion and long-term cognitive impairment among professional or elite sport-persons: a systematic review

Abstract

IntroductionUnderstanding whether concussion in sport is associated with worsening cognitive function in later life will likely have immediate repercussion on sports concussion prevention and management policy and sporting rules and regulations. This systematic review aims to summarise the evidence on the association between concussion sustained by professional/elite athletes and long-term cognitive impairment.MethodsEmbase, PubMed and Web of Science were used to search for eligible studies. Studies including professional/elite athletes from any sport were considered. Three comparison groups were considered: internal comparison (concussed vs non-concussed athletes within the same sample); between-sport comparison (contact sport athletes vs non-contact sports ones); external comparison (athletes vs samples of the general population or population norms).Results14 studies were included (rugby, American football, ice hockey players, boxers and marital art fighters). The general quality of the evidence was poor. The overall evidence, weighted for type of comparison and study quality, points towards an association between sustaining a sport-related concussion and poorer cognitive function later in life in rugby, American football and boxing, although it is unclear to what extent this is clinically relevant. Data on ice hockey and martial arts were too sparse to allow conclusions to be drawn.ConclusionHigh-quality, appropriately designed and powered epidemiological studies are urgently needed to assess the association between sustaining a sport-related concussion and cognitive impairment later in life. Particular emphasis should be put on the clinical translational value of findings.

Predictors and Correlates of Perceived Cognitive Decline in Retired Professional Rugby League Players

“…The extent to which repetitive neurotrauma from earlier in life participation in contact and collision sports is related to later-in-life cognitive decline and impairment is not well-understood ( 1 , 2 ). Most of the research published to date has been conducted in former amateur and professional American football players ( 2 , 3 ), while there are fewer studies in other contact and collision sports.…”

A population‐based study of head injury, cognitive function and pathological markers

“…Establishing long-term associations between HI and pathological markers observed in dementia-free individuals may further help explain subtle cognitive deficits observed or indicate potential future decline. [11][12][13] ª 2021 The Authors. Annals of Clinical and Translational Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association…”

“…Given that studies of HI in older populations are at risk of reverse causality, where cognitive impairment or ageing processes such as frailty may cause HI, 14 the timing of HI needs to be taken into account to help establish long‐term effects from HI incidents, or effects from HI coupled with ageing processes. Establishing long‐term associations between HI and pathological markers observed in dementia‐free individuals may further help explain subtle cognitive deficits observed or indicate potential future decline 11‐13 …”

Episodic memory deficits are associated with impaired insight in traumatic encephalopathy syndrome: Initial findings of the SNAP-CTE study

“…Although there is a clear need for neuropathological biomarkers to identify CTE, what is also needed is a clearer neuropsychological profile of this dementia. There is a growing body of literature investigating whether multiple concussive or subconcussive events contribute to longterm neuropsychological impairment in athletes (12,13). Studies assessing the prevalence of cognitive impairment indicate that clinically diagnosed mild cognitive impairment (MCI) is more frequent in contact-sport athletes than would be expected, according to population estimates (14) or when compared to age-matched, non-contact, sport controls (15).…”