ADD and ADHD are behavioral disorders that are characterized by a variety of forms of inattentiveness, impulsiveness, and forgetfulness.  Unlike other neurological disorders, where the symptoms are a clearly defined set of behaviors or indications, AD(H)D is not especially well defined.  It may not even be a single definable disorder, but instead a collection of distinct ones that have been collected under a single definition.  As a result of this, a single set of conditions has not been defined.  Instead, several compilations of symptoms have been set down over the past decades, including that present in the DSM-IV and the definition used by the American Psychiatric Association.  What follows is the definition used by the latter, as of 1994:
 
 

The clinical features of ADHD include the following:
 

• often shifts from one uncompleted activity to another
• often loses things necessary for tasks
• the individual has difficulty sustaining attention
• is easily distracted
• often does not seem to listen
• often shifts from one uncompleted activity to another
• often loses things necessary for tasks
• often interrupts or intrudes on others
• has difficulty awaiting turn in groups
• often blurts out answers to questions
• often engages in physically dangerous activities without considering the consequences or often talks excessively
• has difficulty playing quietly
• has difficulty remaining seated
• often fidgets or squirms in seat
• has difficulty following instructions.

Taking a sample of these, one should immediately note that these skills are a necessity to succeed at school and in the workforce.

It should be noted that the symptoms differ in each case, especially in adult ADHD.  The common thread in most cases is a deficit in what could be described as "executive functions."  There are five major areas under which these can be grouped:

• Organization
• Sustained Focus
• Sustaining Motivation
• Anger and emotional control (not included in DSM-IV)
• Working Memory and retrieval

As a result of this difficulty, Ciba and Novartis, makers of Ritalin and Ritalin SR state the following in their product description:
1: the diagnosis of this syndrome (ADHD) should not be made with finality when these symptoms are of comparably recent origin
2: Adequate Diagnosis requires the use of not only medical but of special psychological, educational, and social resources
3: Drug treatment is not indicated for all children with this syndrome
4: Ritalin should not be used in children under six years
5: drug treatment (should only be considered in light of the complete history and evaluation of the child)
Prescription should not depend solely on the presence of one or more of the behavioral characteristics ⁽³⁾
 

As can be seen from the warnings of the manufacturers of Ritalin, the use of the drug should not be the first method of treatment for suspected ADHD.  Unfortunately, the manufacturer's directions are not always followed.
 
 
 
 

1: The American Psychiatric Association (1994), Diagnostic and Statistical Manual of Mental Disorders, 4th edition, pp. 78-85. American Psychiatric Association, Washington D.C.

2: Bowes, Mark. "ADHD in adults: Definition and Diagnosis." NeuroPsychiatry Reviews. Volume 2, number 1, February 2001. Link

3: Ritalin Prescribing information.  Novartis.  Revised January 2001.    Link