Answer:
ADHD or attention-deficit hyperactivity-disorder (sometimes referred to as ADD) is a neurobehavioral developmental disorder. ADHD is not contagious; individuals with ADHD have had it since birth. Pre-mature birth, hereditary factors (parents who have ADHD), and exposure to toxic chemicals can contribute to the likelihood of acquiring ADHD. ADHD can also be influenced by environmental factors, including amount of time spent watching television, and possibly video games. Scientific studies prove conclusively that screen time is associated with attention problems.
ISU study finds TV viewing, video game play contribute to kids' attention problems - http://www.news.iastate.edu/news/2010/jul/TVVGattention