It is possible to become pathologically addicted to video games without the use of drugs or other addictive substances. Video game users who are addicted usually use the virtual world supplied by video games in order to connect with others through the internet and world and it is quite common for this to occur because they struggle to interact socially and therefor use the video game world as a source of interaction. There are also statistics that show that men and boys are more likely to become addicted to video games compared to women and girls, although i believe that when some teen users are classed as addicts they aren't actually addicted they just thoroughly enjoy playing video games as a hobby that they can later discuss among their friends while still having other hobbies.
http://www.addictionrecov.org/Addictions/?AID=45
http://www.video-game-addiction.org/
http://www.addictionrecov.org/Addictions/?AID=45
http://www.video-game-addiction.org/