The evidence linking amateur boxing and chronic traumatic brain injury is not strong, concludes a study published on bmj.com.
As such, the researchers say they cannot firmly prove nor reject the theory that amateur boxing leads to chronic brain injury.
Although the evidence for chronic traumatic brain injury in amateur boxing is less clear cut than that in professional boxing, the safety of amateur boxing continues to be questioned.
The British Medical Association wants a complete ban on boxing (amateur and professional), mainly because of the purported risk of cumulative brain injury. However, no recent or systematic review has been performed to assess the evidence for this in the amateur sport.
So a team of sports physicians and clinical academics reviewed the evidence to determine whether amateur boxing leads to chronic traumatic brain injury.
They identified 36 observational studies of amateur boxing and chronic traumatic brain injury. Differences in study design and quality were taken into account to minimise bias. They defined chronic traumatic brain injury as any abnormality in neurological examination, brain imaging, psychometric testing, or electroencephalography (a measurement of the brain's electrical activity).
Overall, 15 (42%) of the 36 studies concluded that relevant abnormalities were present, at least in a proportion of boxers studied. However, the quality of evidence was generally poor.
The best quality studies were those involving psychometric tests and these yielded the most conclusive negative results (no long-term effect of boxing on brain function). Only four of 17 (24%) better quality studies found any indication of chronic traumatic brain injury in a minority of boxers studied.