Is adhd characterized by extreme hyperactivity?

It Certainly can be: Adhd stands for attention deficit hyperactivity disorder so yes, adhd can be characterized by extreme hyperactivity. Of course, not all children with adhd will exhibit this. Some children with adhd can seem like they are the "energizer bunny". They are always on the go, have difficulty sitting still, fidget, and talk excessively. There are other disorders in children that can mimic adhd.

Sometimes: Hyperactivity, as it is usually thought of, diminishes dramatically as the person ages. So presence or absence of hyperactivity is academic. Adhd is a neurologic problem associated with poor executive brain function. So management of brain is what's impeded. Activity can be mismanaged leading to underactivity or over activity. Later in life, the problem is more internal than external.

SOMETIMES: There is often a confusion of terms of add and adhd . There is attention issues with inattentiveness and then there may also be a mix of inattentiveness and hyperactivity. The level of hyperactivity can certainly vary.