- One of the commonest psychiatric affliction of the school going population.
- It is thrice as common in boys
- The characteristic features are:
- Age inappropriate hyperactivity
- Class I: Hyperactivity, Impulsiveness and Inattention all three are present
- Class II: Hyperactivity and Impulsiveness present only
- ClassIII: Only Inattention present. It is the least common variant.
Predominantly inattentive type symptoms may include: 
- Be easily distracted, miss details, forget things, and frequently switch from one activity to another
- Have difficulty focusing on one thing
- Become bored with a task after only a few minutes, unless doing something enjoyable
- Have difficulty focusing attention on organizing and completing a task or learning something new
- Have trouble completing or turning in homework assignments, often losing things (e.g., pencils, toys, assignments) needed to complete tasks or activities
- Not seem to listen when spoken to
- Daydream, become easily confused, and move slowly
- Have difficulty processing information as quickly and accurately as others
- Struggle to follow instructions.
Predominantly hyperactive-impulsive type symptoms may include: 
- Fidget and squirm in their seats
- Talk nonstop
- Dash around, touching or playing with anything and everything in sight
- Have trouble sitting still during dinner, school, and story time
- Be constantly in motion
- Have difficulty doing quiet tasks or activities.
and also these manifestations primarily of impulsivity: 
- Be very impatient
- Blurt out inappropriate comments, show their emotions without restraint, and act without regard for consequences
- Have difficulty waiting for things they want or waiting their turns in games
Most people exhibit some of these behaviors, but not to the degree where such behaviors significantly interfere with a person’s work, relationships, or studies. The core impairments are consistent even in different cultural contexts
If the DSM IV criteria are used rather than the ICD 10 criteria, there is a 3-4 times greater chance of diagnosing ADHD.
IA. Six or more of the following signs of inattention have been present for at least 6 months to a point that is disruptive and inappropriate for developmental level:
- Often does not give close attention to details or makes careless mistakes in schoolwork, work, or other activities.
- Often has trouble keeping attention on tasks or play activities.
- Often does not seem to listen when spoken to directly.
- Often does not follow instructions and fails to finish schoolwork, chores, or duties in the workplace (not due to oppositional behavior or failure to understand instructions).
- Often has trouble organizing activities.
- Often avoids, dislikes, or doesn’t want to do things that take a lot of mental effort for a long period of time (such as schoolwork or homework).
- Often loses things needed for tasks and activities (such as toys, school assignments, pencils, books, or tools).
- Is often easily distracted.
- Often forgetful in daily activities.
IB. Six or more of the following signs of hyperactivity-impulsivity have been present for at least 6 months to an extent that is disruptive and inappropriate for developmental level:
- Often fidgets with hands or feet or squirms in seat.
- Often gets up from seat when remaining in seat is expected.
- Often runs about or climbs when and where it is not appropriate (adolescents or adults may feel very restless).
- Often has trouble playing or enjoying leisure activities quietly.
- Is often “on the go” or often acts as if “driven by a motor”.
- Often talks excessively.
- Often blurts out answers before questions have been finished.
- Often has trouble waiting one’s turn.
- Often interrupts or intrudes on others (example: butts into conversations or games).
II. Some signs that cause impairment were present before age 7 years.
III. Some impairment from the signs is present in two or more settings (such as at school/work and at home).
IV. There must be clear evidence of significant impairment in social, school, or work functioning.
V. The signs do not happen only during the course of a Pervasive Developmental Disorder, Schizophrenia, or other Psychotic Disorder. The signs are not better accounted for by another mental disorder (such as Mood Disorder, Anxiety Disorder, Dissociative Identity Disorder, or a Personality Disorder). 
To make the diagnosis of ADHD, a number of other possible medical and psychological conditions must be excluded.
Medical conditions that must be excluded include:
- lead poisoning,
- chronic illness,
- hearing or vision impairment,
- substance abuse,
- medication side effects,
- sleep impairment and
- child abuse and
- cluttering (tachyphemia) among others.
Methods of treatment often involve some combination of behavior modification, life-style changes, counseling, and medication. A 2005 study found that medical management and behavioral treatment is the most effective ADHD management strategy, followed by medication alone, and then behavioral treatment. 
Psychological therapies used to treat ADHD include psychoeducational input, behavior therapy, cognitive behavioral therapy (CBT), interpersonal psychotherapy (IPT), family therapy, school-based interventions, social skills training and parent management training.
Stimulants are the most commonly prescribed medications for ADHD. The most common stimulant medications are the chain subsitituted amphetamine
Other non-stimulant medications
- Atomoxetine and
are the only non-stimulant drug approved for the treatment of ADHD.
- “Attention Deficit Hyperactivity Disorder (ADHD).” Health & Outreach. Publications.http://www.nimh.nih.gov/health/publications/attention-deficit-hyperactivity-disorder/complete-index.shtml July 15, 2009
- Jensen PS, Garcia JA, Glied S (September 2005). “Cost-effectiveness of ADHD treatments: findings from the multimodal treatment study of children with ADHD”. The American Journal of Psychiatry 162(9): 1628–36. doi:10.1176/appi.ajp.162.9.1628. PMID 16135621