Sports Concussions Lessen Blood Reaching Kids' Brains

Nov. 30, 2011— -- Concussions can reduce blood flow to young athletes' brains for a month or more, although their brains also appear more resilient in many ways than those of similarly injured adults, researchers report.

A single sports-related concussion in a young person generally produces minor trauma, which the researchers described as more of a disruption to brain function than the structural and metabolic damage similar concussions inflict on adult brains.

The findings come from a study assessing the effects of concussions on nine boys and three girls, ages 11 to 15, who'd been injured during football, soccer or wrestling. The study group comprised three girls injured while playing soccer, one boy injured while wrestling and seven boys injured on the football field. Two football players were knocked unconscious during the incidents; three of the football players had suffered previous concussions more than a year earlier.

When the researchers, led by Dr. Todd Maugans, a pediatric neurosurgeon at Cincinnati Children's Hospital Medical Center, compared injured athletes' brains to brains of healthy youngsters of the same age and sex, MRIs found less blood flowing through the injured athletes' brains in the immediate aftermath of their head injuries. The brain-injured athletes also had slower reaction times.

However, by the two-week mark, blood flow for 27 percent of the injured athletes returned nearly to the levels of healthy subjects and most of their symptoms had resolved. Follow-up at a month or more found 64 percent of the injured athletes had normal blood flow again, and everyone's reaction times were normal, according to results published online today in the journal Pediatrics.

With 36 percent of the group experiencing persistent blood flow reductions a month or more after their injuries, the findings "suggest that the brain may not be fully recovered from a physiological injury for more than a month," Maugans told ABCNews.com "Ours is the first study to suggest that, by examining the pathophysiology (biological nature of the injury) rather than just the clinical manifestations such as symptoms and neuropsychological alterations."

The authors theorized that diminished blood flow produces some of the symptoms associated with concussions, most of which resolve with time. They were unable to say what long-term effects might result from lessened blood flow. Maugans said that in addition to further studying altered blood flow in the brains of kids who have suffered concussions in organized sports, "it needs to be studied in adults (college and pro athletes) who have not been studied at all."

The 13-year-old wrestler suffered a severe concussion, which left him with a few minutes of weakness in his arms and legs, followed by confusion, severe headache and vomiting. Emergency MRI studies of his brain, spinal cord and blood vessels in his neck were normal, but two weeks after his injury, blood flow remained about 35 percent of normal, and he left the study for medical treatment, the authors wrote.

Attention has increased in recent years to the long-term cognitive effects of brain injuries, particularly blows to the head during sports. With that has come increased use of Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT), which was among the tools used by Maugans and his fellow researchers to assess the effects of concussions on young athletes. A computerized, 20-minute quiz, ImPACT evaluates health history, symptoms, sleep and medications, along with word recall and reaction time. An athlete takes the test to establish a baseline level of brain function and can repeat it after a concussion to detect impairments in cognition and other brain functions.

Larger Studies, Longer Follow-up Needed to Understand Effects on Young Brains

Although the small number of subjects limited their findings, Maugans and his co-authors said their work represented a significant step in understanding the biological effects of sports-related head injuries among pre-teens and teens. Most concussion studies have focused on symptoms of adults, rather than children, whose developing brains are both vulnerable, and according to this study, resilient as well.

The two youngest subjects in the concussion study, ages 11 and 12, showed no lessening of blood flow through their brains, which actually had more blood flow than that of healthy subjects. The study authors suggested that this initially high blood flow might be a characteristic response in the brains of younger children. They said the next step would be to conduct larger studies with longer periods of follow-up.

An estimated 3.8 million youngsters suffer sports- and recreation-related concussions each year. Studies have linked these brain injuries to such neurological disorders as dementia and Parkinson's disease, along with a newly identified condition, chronic traumatic encephalopathy, blamed for suicides by some pro athletes.

New research linking repeatedly heading a soccer ball to potential cognitive impairment and brain trauma to adds to the body of evidence about the brain's vulnerability to being hit. Researchers from Albert Einstein College of Medicine in New York concluded from their study of 32 amateur soccer players that brain changes from heading the ball more than 1,000 to 1,500 times in a year "may represent a form of repetitive mild trauma and may be associated with cognitive impairment." Exceeding that threshold could create "brain abnormalities" akin to those seen in traumatic brain injuries, according to a presentation being made today at the Radiological Society of North America annual meeting in Chicago.The researchers said the threshold could form the basis of public health interventions to minimize damage from head blows.