This Publication Is Searchable The Merck Manual of Diagnosis and Therapy Section 19. Pediatrics Chapter 262. A persistent and frequent pattern of developmentally inappropriate inattention and impulsivity, with or without hyperactivity. Although validation of ADD as a specific diagnosis has been difficult, no study has been able to establish the converse. ADD is implicated in learning disorders and can influence the behavior of children at any cognitive level, except for moderate to profound mental retardation.
ADD tends to occur in families and is common in first-degree biological relatives.
ADD with hyperactivity and impulsivity is seen 10 times more frequently in boys than girls. Many now believe that ADD is a difference rather than a deficit or disorder in brain biochemistry resulting in a difference in approach to learning. Etiology Etiology is unknown. Several theories advocating biochemical, sensorimotor, physiologic, and behavioral correlates and manifestations have been proposed. The leading hypothesis suggests neurotransmitter abnormalities in dopaminergic and noradrenergic systems with decreased activity or stimulation in upper brain stem and frontal-midbrain tracts.