• Inattention
• Hyperactivity
• Impulsivity⁴

Inattention may be the main problem with some people, while hyperactivity and impulsivity may be the main problems for others. Most people affected by ADHD have problems in all three symptom areas, hence the prevalence of the "combined" type of ADHD.

Difficulty in school or at work, troubled relationships with family and peers, and low self-esteem are some of the issues commonly faced by people with ADHD.⁹ Although ADHD is often diagnosed in childhood, many people are not diagnosed until they reach adulthood.

ADHD testing and diagnosis

Because everyone can, from time to time, show signs of inattention, hyperactivity and impulsivity, professionals use strict criteria when diagnosing ADHD. The Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision (DSM-IV-TR^®) specifies that for the diagnosis of ADHD to be made:

• The behaviors must appear early in life (before age 7)
• The behaviors must be present for more than 6 months
• ADHD behaviors must have a negative effect on the person's functioning at school, on the job, or in social situations⁴

ADHD diagnosis must be made by a trained professional, such as a psychiatrist, psychologist, or primary care  physician. Family members and teachers can be particularly helpful in aiding the ADHD diagnosis by providing detailed information about the history of behaviors they have observed in the patient.

Symptoms of ADHD in Children

Adult ADHD Symptoms

Symptoms of ADHD in Children

Inattention

• Fails to pay close attention to details or makes careless mistakes and is easily distracted
  
• Has difficulty maintaining attention in tasks or play activities, has difficulty organizing tasks or activities
• Does not seem to listen when spoken to directly
• Does not follow directions and fails to complete schoolwork, tests, chores, or on-the-job duties
• Is often forgetful in daily activities

Hyperactivity

• Fidgets with hands or feet or squirms in seat
• Leaves seat in classroom or in other situations in which remaining seated is expected
• Runs or climbs excessively when inappropriate
• Has difficulty playing or engaging in leisure activities quietly
• Often talks excessively

Impulsivity

• Blurts out answers before questions have been completed
• Has difficulty waiting for a turn
• Interrupts or intrudes on others (for example, butts into conversations or games)

Adult ADHD Symptoms

Inattention—More than occasionally "wandering off" mentally

• Distracted by irrelevant sights or sounds
• Misses details or makes careless mistakes
• Has difficulty following instructions
• Loses and forgets things

"Can't sit still."—The adult version of what you'd consider "hyperactivity" in a child

• Fidgets or gets up and roams around the room
• Attacks several tasks at once (and usually accomplishes none)

Impulsive behavior—Especially as a consistent part of your everyday actions

• Takes action before thinking about the consequences
• In conversation, interrupt others, or blurts out inappropriate comments
• Experiences difficulty waiting in line or for a turn