London, October 6 : A systematic review of observational studies has shown that the evidence suggesting that amateur boxing leads to chronic traumatic brain injury is not strong.

The team of sports physicians and clinical academics, which carried out the study, though expressing their inability to firmly prove or reject the theory that amateur boxing led to chronic brain injury, insisted that the evidence linking the two was not strong.

During the study, the researchers 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.

The researchers say that the studies defined chronic traumatic brain injury as any abnormality in neurological examination, brain imaging, psychometric testing, or electroencephalography.

According to them, overall 15 of the 36 studies concluded that relevant abnormalities were present, but the quality of evidence was generally poor.

The researchers said that the best quality studies were the ones that had involved psychometric tests. They said that such studies yielded the most conclusive negative results i.e. boxing does not affect brain function in the long-term.

Only four of the 17 better quality studies found any indication of chronic traumatic brain injury in a minority of boxers studied, the researchers added.

It was also observed that only one of the six studies, wherein magnetic resonance imaging was used, confirmed the presence of relevant abnormality. The researcher said that the abnormality was a cyst in a single boxer, which was possibly congenital.

The authors of the study insist that the link between amateur boxing and chronic brain injury was generally confirmed by studies of poorer quality and design, while studies of sufficient quality showed a weak association.

The review has been published in the online edition of the British Medical Journal. (ANI)