What is the definition or description of: add/adhd?

Simple description: Adhd is a clinical disorder which research has supported is a dysfunction of the pre-frontal cortex of the brain; the brain's 'filter'. Patient's have trouble filtering incoming data. Difficulty in three areas: 1 - prioritizing incoming information/ paying attention, 2 - regulating physical reactions and impulses and 3- regulating emotional impulses and reactions.

Poor regulation : Impulsivity, innattention /distractability and for adhd-hyperactivity before the age of 7(or for dsm5-age 12) that causes significant dysfunction-with no identifiable reason.