Particularly in young children, inattentive, impulsive or hyperactive behaviors can be developmentally inappropriate for their age group:

• • Poorly sustained attention or persistence of effort, particularly if tasks are boring, tedious, repetitive or take too long. Individuals with ADHD may shift from one uncompleted activity to another, lose concentration or fail to complete routine assignments without supervision. They may find their concentration is interrupted by irrelevant thoughts or external events, making it more difficult to resist distractions. 
  • Impaired impulse control or delayed gratification are often noted in  individuals being unable to think before acting, wait their turn while playing or talking with others, work for larger, longer-term rewards and inhibit behaviors as a situation demands. 
  • Excessive, unfocused or unregulated activity. Individuals find it difficult to control their activity level. They may be excessively fidgety or restless and engage in behaviors either not relevant nor appropriate for the task or situational demands. Younger children may squirm in their seats, tap things or shift position while performing tasks. Hyperactivity may decline with age and, by adulthood, be a more subjective feeling of needing to be busy.

While ADHD appears to arise from multiple causes, the evidence for its genetic basis is overwhelming and irrefutable—accounting for 65-75% of all clinical cases. ADHD:

• Occurs far more among biological family members, shows increasing co-occurrence as genetic similarity increases (from siblings to identical twins, for example) and might be associated with variations in genes that regulate dopamine activity in the brain.
• Probably arises from a combination of risk genes, likely to be better identified in the future. Genetic testing may eventually lead to more accurate diagnosis, subtyping and treatment, with different medications targeting different genetic subtypes.

In 35% of cases, ADHD stems from early brain injuries or such disruptions to brain development as:

• Maternal alcohol consumption or smoking during pregnancy
• Pregnancy or birth complications
• Lead poisoning
• Atypical autoimmune reactions to bacterial infections
• Head trauma, brain tumors or stroke

Individuals with seizures or epilepsy have a 2-3 times greater likelihood of ADHD. Sedatives or anticonvulsant drugs may lead to ADHD as a side effect or make pre-existing ADHD features worse.

Research does not support ADHD being caused by consuming food additives, preservatives or sugar—though allergies can worsen symptoms. 

Now recognized as occurring in children, adolescents and adults, ADHD is more common in individuals with a history of:

• • Oppositional defiant disorder (ODD) 
  • Conduct disorder
  • Learning disabilities 
  • Bipolar disorder in children
  • Tourette’s syndrome

Individuals with ADHD can be successful in school, work and life. However, the condition can lead to an array of serious consequences. For example:

School failure:

• This includes poor academic productivity, underachievement and learning disabilities. 
• Because students with ADHD produce far less schoolwork than peers and perform at lower achievement levels relative to their intellectual abilities, 35-50% will also have a learning disability:

• • 30% have reading disorders
  • 10-25% have academic difficulties in spelling, math or writing
  • 10-25% have language problems, including verbal interactions with others

• Elementary school children with ADHD who also show aggressiveness, defiance, lying or stealing are most likely at risk for later antisocial behavior problems.
• Well-behaved children may also be at risk, most commonly in educational performance and attainment, and are more likely to: 

• • Be held back a grade (25-50%)
  • Need special education (50-80%)
  • Be suspended for inappropriate conduct (10-20%)
  • Be expelled (10-15%) 
  • Quit before completing high school (30-40%)

Delinquency, aggression or conduct problems:

• Studies suggest 45-84% of those with ADHD also have anti-social and aggressive behavior (see oppositional defiant disorder or ODD) shown by arguing, defiance toward adults or other authorities, stubbornness, disobedience, temper outbursts, destructiveness and verbal or physical aggression. 

Excessive emotional displays or immaturity:

• Children in particular may show exaggerated emotions, overreacting to frustrating, provocative or stressful situations. 
• They may have lower frustration tolerance, be more moody and emotionally sensitive, or be quicker to show anger, sadness, elation or other normal emotions than is normal for their age. 
• Low self-esteem is common by late childhood or early adolescence. 
• Children, adolescents and adults are at risk for depression and other anxiety and mood disorders.

Social relationship problems:

• At least half of those with ADHD have problems beginning or maintaining social relationships or resolving conflicts with family members, peers or other adults, causing stress and disruption. 
• They may be described as self-centered, demanding, insensitive to the feelings of others and unappreciative of assistance (especially common in ODD cases).

Other challenges associated with ADHD:

• Accidental injuries
• Substance abuse
• Job failure

Combined type, the most common type of ADHD, where both inattention and hyperactivity/impulsivity are present, as well as inattention and distractibility and early onset of symptoms.

Predominantly hyperactive type, including impulsivity, where a child seems to move about constantly, including in inappropriate situations; or excessively fidgets, taps or talks. In adults, it may be extreme restlessness or wearing others out with constant activity.

Predominantly inattentive type, where a person is easily distracted, has trouble paying attention to details, organizing or finishing tasks and often forget routine chores (paying bills on time or returning phone calls).

Evaluation

Individuals with ADHD can lead complete and successful lives. However, without diagnosis and treatment, ADHD may have serious consequences (read about risks). For a diagnosis, several symptoms must be present before age 12, with children having at least six symptoms and adolescents age 17+ and adults having at least five symptoms. 

While there is no cure, ADHD treatments can be effective in either reducing the level of symptoms or the degree to which they impair adjustment. Care begins with a behavioral/psychological, educational and/or medical evaluation. Beyond observational data and paper-and-pencil questionnaires, neuropsychological assessment, in particular, may be helpful in identifying underlying neurocognitive mechanisms associated with ADHD. 

Learn more about CFI’s Assessment Center

Treatment

Evaluation is followed by multi-disciplinary treatment from the mental health, education and medical professions—provided periodically over long intervals—so individuals with ADHD can learn to better cope with their behavioral disability. Effective ADHD treatments include supports and skills-building to help children, adolescents and adults cope with the disorder and related challenges, including: 

• Attentional difficulties and impulse control problems
• Organizational and time-management difficulties
• Executive function (EF) deficits
• Learning disorders and academic difficulties
• Social skills difficulties 
• School observation and consultation, including IEP/504 planning and school placement issues

More specifically:

For children:

• Behavioral parent training 
• Executive functioning (EF) and organizational skills training 
• Behavioral interventions in educational settings
• Special educational placements
• Information-based counseling of clients and family members

For adults:

• • Learning practical methods of coping with disability
  • Enlisting others to help organize/structure work-related activities
  • Medication: Stimulants and nonstimulants can be effective for children, adolescents and adults.

Little or no evidence of effectiveness:

• • Popular but ineffective treatments include: elimination of sugar or food additives, long-term psychotherapy, biofeedback or neurotherapy, high-dose vitamins, sensory integration or cognitive therapy, self-instruction training.
  • Social skills training has shown less promise and contradictory research findings. 

References

Association for Behavioral and Cognitive Therapies (ABCT)

Centers on Disease Control (CDC)

Healthline

Mayo Clinic

National Institute of Mental Health (NIMH)

National Institute of Mental Health (NIMH) health statistics

National Resource Center on ADHD