It doesn't affect just kids. That's one often-surprising fact about ADHD, or attention-deficit hyperactivity disorder. About 9 million adults in the USA have it, and yet the condition is often unrecognized in an older population. Here are four more things you may not know about adult ADHD:Symptoms start young. Even if you were never diagnosed, all adults with ADHD had it as kids. Some children outgrow symptoms; in others, they decrease in severity with age. But about one-third will continue to have significant symptoms as adults. Signs include restlessness, impulsive behavior, trouble concentrating, disorganization, mood swings and tempers, and trouble coping with stress.It's difficult to diagnose in adults. Symptoms tend to be more varied and less clear-cut. Plus, at some point, most of us will feel scattered and easily distracted, and we'll probably blame it on a stressful, over-extended lifestyle. But if inattention, hyperactivity or impulsive behavior continually disrupts your life, talk to your doctor. No single test can confirm a diagnosis; your doctor may perform a physical exam, ask you questions, look at your childhood history, and interview spouses or partners. For a diagnosis, health professionals look for a persistent pattern beginning no later than age 7. The most effective treatment includes a combination of medication and psychotherapy.Don't blame sugar. Research discounts excess sugar, poor parenting or food allergies as causes, as some theories suggest. The exact cause of ADHD is a mystery, but evidence has shown that genetics plays a big role - if one person in a family has it, there's about a 25% probability that another family member will be diagnosed. Structural differences in the brain also may be a factor.Linked to dementia, creativity. Those are the findings from two separate studies published last year: The first, out of Argentina, suggests adults with ADHD are more than three times as likely to develop a common form of dementia later in life; more research is needed. On a more positive note, a study of 60 undergraduate students found that those with ADHD showed more creativity compared with those who did not. Researchers found the individuals with the condition liked generating ideas, but weren't as good at completing the tasks.- The Doctors is an Emmy-winning daytime TV show with pediatrician Jim Sears, OB-GYN Lisa Masterson, ER physician Travis Stork, and plastic surgeon Andrew Ordon. Check www.thedoctorstv.com for local listings.