Sheer critical mass could be one reason why Chinese doctors had to come up with a definition of Internet addiction. Net users aged 18-30 make up half of China's estimated online population of some 250 million people, and 10% of that group of Netizens are addicted (about 70% of them male), China Daily reports. That's 12.5 million addicts. The announcement, by Dr. Tao Ran of Beijing's Military General Hospital, was one of two firsts for China: the first diagnostic definition of Internet addiction "amid efforts to address an increasing number of psychological problems that reportedly result from Internet overuse" and China's first Internet addiction clinic. "China could become the first country to classify Internet addiction as a clinical disorder and plans to lead the world by registering the condition with the World Health Organisation," the Times of London reports. Symptoms include "yearning to get back online, mental or physical distress, irritation and difficulty concentrating or sleeping." Dr. Tao "classifies as addicts those who spend at least six hours online a day and have shown at least one symptom in the past three months." He said 80% can be cured with treatment that "usually lasts about three months." The Times adds that "research by the internet media company InterActiveCorp showed that 42% of Chinese youngsters polled felt addicted to the internet, compared with 18% in the US."