Boxing-acute complications and late sequelae: from concussion to dementia.

BACKGROUND: Boxing has received increased public attention and acceptance in recent years. However, this development has not been accompanied by a critical discussion of the early and late health complications.
METHODS: We selectively review recent studies on the acute, subacute, and chronic neuropsychiatric consequences of boxing.
RESULTS: Cerebral concussions ("knock-outs") are the most relevant acute consequence of boxing. The number of reported cases of death in the ring seems to have mildly decreased. Subacute neuropsychological deficits appear to last longer than subjective symptoms. The associated molecular changes demonstrate neuronal and glial injury correlated with the number and severity of blows to the head (altered total tau, beta-amyloid, neurofilament light protein, glial fibrillary acidic protein, and neuron-specific enolase). The risk of a punch-drunk syndrome (boxer's dementia, dementia pugilistica) as a late effect of chronic traumatic brain injury is associated with the duration of a boxer's career and with his earlier stamina. There are similarities (e.g. increased risk with ApoE4-polymorphism, beta-amyloid pathology) and differences (more tau pathology in boxers) compared with Alzheimer's disease.
CONCLUSION: Protective gear has led to a remarkable reduction of risks in amateur boxing. Similar measures can also be used in professional boxing, but may decrease the thrill, which does appeal to many supporters.