symptoms similar to the symptoms of addiction, such as tolerance (increased Facebook use over time), withdrawal (irritability when unable to access Facebook), and cravings to access the site. "Our findings suggest that there may be shared mechanisms underlying both substance and behavioral addictions," Hormes added. The prevalence of internet addiction varies considerably between countries and is inversely related to the quality of life. Many countries in Asia (particularly China, South Korea, and Japan) have raised public concern over the recent rise in internet addictions. Eating disorders One study found that the more time teenage girls spend on Facebook, the higher their risk of developing negative body images and eating disorders. Other studies have also found a correlation between social media use and disordered eating. In women college students, social media use predicts disordered-eating symptomatology and other related variables (such as the drive for thinness and body dissatisfaction). For men, media use predicted endorsement of personal thinness and dieting. Social media and ADHD An emerging body of research suggests that internet addiction and unhealthy social media activity may be more prevalent in ADHD individuals. Male college students are more likely than women college students to be screened positively for adult ADHD; however, the overall association between Internet addiction and attention deficit is more significant in females. Clinical psychologist Michelle Frank stated, "The ADHD brain is already one that struggles with motivation, activation, organizing behaviors, managing time, and maintaining focus...Technology, left un-managed, makes these struggles considerably more difficult. The unique challenges that result are prime vulnerabilities to the common pitfalls of technology use." Although many factors contribute to ADHD (including genes, teratogens, parenting styles, etc.), a sedentary lifestyle centered on television, computer games, and mobile devices may increase the risk for ADHD. In the view of Dr. Robert Melillo, founder of the Brain Balance Program, "When kids play computer games, their minds are processing information in a much different way than kids who are, say, running around on a playground... Recent studies have shown that playing computer games only builds very short-term attention that needs to be rewarded frequently." Positive correlates of social media use Several positive psychological outcomes are related to Facebook use. People can derive a sense of social connectedness and belongingness in the online environment. Importantly, this online social connectedness was associated with lower levels of depression and anxiety, and greater levels of subjective well-being. Messaging can also be