Dr. Susannah Hills, a pediatric airway surgeon and professor at Columbia University Irving Medical Center, joined CBS News to discuss what's known about these long-lasting illnesses.
Dr. Monica Bhatia is Johnny's doctor and the chief of pediatric stem cell transplantation at NewYork-Presbyterian/Columbia University Irving Medical Center.
"There is enormous worldwide concern for brain injury in general and in the potential for soccer heading to cause long-term adverse brain effects in particular," said study author Dr. Michael Lipton.
According to Kimberly Kleinman, a psychologist at NewYork-Presbyterian/Columbia University Irving Medical Center, seasonal affective disorder, or SAD, is a type of depression with a seasonal pattern.
Editor's Note: Gordana Vunjak-Novakovic is a University Professor, a professor at the College of Dental Medicine, and a faculty member of the Vagelos College of Physicians and Surgeons.
