If you think you have ADHD, you'll need to be thoroughly evaluated by a psychologist or psychiatrist to confirm the diagnosis. ADHD has many symptoms. Some symptoms at first may look like normal behaviors for a child, but ADHD makes them much worse and occur more often. Have a look at this huge list of symptoms about ADHD, many teens who struggle with ADHD will exhibit some of these following behaviors. ADHD is one of the most common neurobehavioral disorders of childhood. It is usually first diagnosed in childhood and often lasts into adulthood.