South Korean experts warn that young people's reliance on technology is causing them to forget everyday details such as their phone numbers. Experts say those who rely on technology suffer a deteroriation in cognitive abilities more commonly seen in patients who have suffered a head injury or psychiatric illness. Overuse of technology is said to develop the left side of the brain, but leave the right side of the brain underdeveloped. Researchers say, "The right side of the brain is associated with concentration and underdevelopment affects attention and memory span, which could in as many as 15-percent of cases lead to the early onset of dementia." Researchers say those at highest risk of problems are between the ages of ten and 19 who use their smartphones for more than seven hours each day.