Detailed Instructions: Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.
Q: What happens inside the skull of a soccer player who repeatedly heads a soccer ball? That question motivate a challenging new study of the brains of experienced players that has caused discussion and debate among soccer players, and some anxiety among those of us with soccer-playing children. For the study, researchers at the Albert Einstein College of Medicine in New York selected 34 adults,men and women. All of the volunteers had played soccer since childhood and now competed year-round in adult soccer leagues. Each filled out a detailed questionnaire developed especially for this study to determine how many times they had headed a soccer ball in the previous year, as well as whether they had experienced any known concussions in the past. Then the players completed computerized tests of their memory and other learning skills and had their brains scanned, using a complicated new MRI technique which can find structural changes in the brain that can't be seen during most scans. According to the data they presented at a Radiological Society of North America meeting last month,the researchers found that the players who had headed the ball more than about 1,100 times in the previous 12 months showed significant loss of white matter in parts of their brains involved with memory,attention and the processing of visual information, compared with players who had headed the ball fewer times. This pattern of white matter loss is "similar to those seen in traumatic brain injury" , like that after a serious concussion, the researchers reported,even though only one of these players was reported to have ever experienced a conc ussion. The players who had headed the ball about 1,100 times or more in the past year were also generally worse at recalling lists of words read to them, forgetting or _ the words far more often than players who had headed the ball less.
A:
What is likely to be the cause of memory loss?