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LONDON (AP) — A British study has highlighted degenerative brain damage from repeated blows to the head in a small number of retired soccer players who developed dementia.

Fourteen former players were part of the research that began around 40 years ago, and six brains, which underwent post-mortem examinations, had signs of Alzheimer's disease.

Four were found to have chronic traumatic encephalopathy (CTE) pathology, a possible consequence of repeated impacts to the brain, including heading the ball and concussion injuries from head-to-head collisions.

A previous study of 268 brains from the general population in Britain found a far lower CTE detection rate of 12 percent.