“Attention-deficit/hyperactivity disorder, or ADHD, is a mental illness that affects the way you act and focus. ADHD is usually diagnosed in school-aged children, but it can continue to cause problems into adulthood. About two-thirds of people living with ADHD continue to experience symptoms as an adult. As we learn more about the course of ADHD, it’s becoming more common for teens and adults to be diagnosed with the illness.”