Veronica, Found some information related to AD/HD from add.org that explains the criteria for being diagnosed with these conditions as opposed to just being hyperactive. Hope this helps...
AD/HD is a diagnosis applied to children and adults who consistently display certain characteristic behaviors over a period of time. The most common core features include:
distractibility (poor sustained attention to tasks)
impulsivity (impaired impulse control and delay of gratification)
hyperactivity (excessive activity and physical restlessness)
In order to meet diagnostic criteria, these behaviors must be excessive, long-term, and pervasive. The behaviors must appear before age 7, and continue for at least 6 months. A crucial consideration is that the behaviors must create a real handicap in at least two areas of a person's life, such as school, home, work, or social settings. These criteria set ADHD apart from the "normal" distractibility and impulsive behavior of childhood, or the effects of the hectic and overstressed lifestyle prevalent in our society.
According to the DSM-IV (the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) some common symptoms of ADHD include: often fails to give close attention to details or makes careless mistakes; often has difficulty sustaining attention to tasks; often does not seem to listen when spoken to directly; often fails to follow instructions carefully and completely; losing or forgetting important things; feeling restless, often fidgeting with hands or feet, or squirming; running or climbing excessively; often talks excessively; often blurts out answers before hearing the whole question; often has difficulty awaiting turn.
Please keep in mind that the exact nature and severity of AD/HD symptoms varies from person to person. Approximately one-third of people with AD/HD do not have the hyperactive or overactive behavior component, for example.
And it appears that the most effective treatment for ADHD is a combination of medication (when necessary), therapy or counseling to learn coping skills and adaptive behaviors, and ADD coaching for adults. If you're worried about going the Ritalin route, you may want to try counseling or coaching first. You can find more about coaching for AD/HD here.
And according to emedicine, boys are more likely to be diagnosed than girls although numbers are starting to level out.
Boys are much more likely than girls to be diagnosed with ADHD. At one time, the ratio of boys to girls with ADHD was thought to be as high as 4:1 or 3:1. This ratio has been decreasing, however, as more is known about ADHD. For instance, greater recognition of the inattentive form of ADHD has increased the number of girls diagnosed with the disorder.
Has your nephew been exposed to any type of coaching or counseling yet?