The answer to this question is a bit more complex than it appears at first glance. The reasons for this is twofold; ADD or Attention Deficit Disorder is, in the psychological community, the old term for Attention Deficit Hyperactivity Disorder or ADHD. ADD is also, however, the term used by most lay people to describe people with attention deficit hyperactive disorder who are not hyperactive. In the psychiatric community, the terms are interchangeable. In the lay community, the terms may describe two very different problems.
ADD is the older psychiatric term, used by doctors and researchers for the condition that is today called ADHD. Doctors and researchers no longer use the term ADD at all. In the 80s the DSM, manual of psychiatric diagnosis was revised. The new DSM IV called the disorder that had been previously called ADD, ADHD to reflect the fact that most individuals with ADHD are hyperactive. The DSM IV describes three subtypes of ADHD. The hyperactive/impulsive subtype was labeled ADHD-HI, the Predominantly Inattentive subtype is calledADHD-PI, and the combined type was labeled as ADHD-C.
Lay people, as might be expected, don’t read the DSM IV. They often use the term ADD to refer to anyone with ADHD, and they also sometimes use the term ADD to refer to those who are inattentive, but who aren’t impulsive or hyperactive.
Despite the fact that these two terms are used interchangeably by certain people, there is a big difference between Hyperactive/Impulsive ADHD (ADHD-HI) or Combined type ADHD (ADHD-C) and ADHD-PI. Some psychiatrist believe that ADHD-PI is so different from the other subtypes of ADHD that the American Psychiatric Association is considering removing the Predominantly Inattentive subtype from the DSM category shared by the other ADHD sub-types and assigning it a new category when it publishes the new DSM V in 2013.
Russell Barkley, PhD, an ADHD expert, has said that Predominantly Inattentive ADHD is the real ADD. He has researched the inattentive subtype, and has discovered that the major symptom is a deficit in attention. They tend to not be hyperactive or impulsive, and these people respond to treatment differently. They also have different long term problems and comorbidities.
ADD is the old professional name for ADHD; it is also the label that many people use to name to what physicians now call Predominantly Inattentive ADHD. When the research and psychiatric community changed the terminology from ADD to ADHD, they intended for these label to be used interchangeably. Some of the lay community, however, has adopted the ADD name to describe people with inattentiveness without hyperactivity.