Attention-Deficit/Hyperactivity Disorder (ADHD)

Attention Deficit Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder, usually first diagnosed in childhood, characterized by inattention, impulsivity, and/or hyperactivity.


The general prevalence of ADHD is estimated at between 5-9% (average 7%) for children and adolescents,[1] 3-5% for adults, and a world-wide prevalence of 5%.[2][3]


Childhood ADHD has been found to be associated with worse educational occupational economic, social, and health related outcomes.


70% of school-aged children with ADHD have at least one other co-morbid psychiatric disorder such as generalized anxiety disorder, oppositional defiant disorder, obsessive-compulsive disorder, tic disorders or depression.

Risk Factors

Genetic factors are most important in ADHD. There is heritability is about 75%. Parents with ADHD have a >50% chance of having a child with ADHD. Close to 25% of children with ADHD have parents who meet the formal diagnostic criteria for ADHD. Twin studies have placed the heritability of ADHD at 76%. First-degree relatives of diagnosed ADHD individuals being somewhere between 30 to 40%. Genes that are implicated include DAT1, DRD4, DRD5, DBH, 5-HTT, 
HTR1B, and SNAP-25.[4] Non-genetic risk factors include perinatal stress and low birth weight, traumatic brain injury, maternal smoking during pregnancy, severe early deprivation, and frequent digital media use.[5][6] The influence of later birthdate on ADHD diagnoses has also been investigated, suggesting that children may be diagnosed due to their relative age differences within their peer group at a certain grade level.[7]

Criterion A

A persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development, as characterized by the (1) inattention category and/or (2) hyperactivity and impulsivity category:


At least 6 of the following symptoms have persisted for at least 6 months to a degree that is inconsistent with developmental level and that negatively impacts directly on social and academic/occupational activities:

  1. Often fails to give close attention to details or makes careless mistakes in schoolwork, at work, or during other activities (e.g. - overlooks or misses details, work is inaccurate).
  2. Often has difficulty sustaining attention in tasks or play activities (e.g. - has difficulty remaining focused during lectures, conversations, or lengthy reading)
  3. Often does not seem to listen when spoken to directly (e.g. - mind seems else where, even in the absence of any obvious distraction)
  4. Often does not follow through on instructions and fails to finish schoolwork, chores, or duties in the workplace (e.g. - starts tasks but quickly loses focus and is easily sidetracked).
  5. Often has difficulty organizing tasks and activities (e.g. - difficulty managing sequential tasks; difficulty keeping materials and belongings in order; messy, disorganized work; has poor time management; fails to meet deadlines).
  6. Often avoids, dislikes, or is reluctant to engage in tasks that require sustained mental effort (e.g. - schoolwork or homework; for older adolescents and adults, preparing reports, completing forms, reviewing lengthy papers).
  7. Often loses things necessary for tasks or activities (e.g. - school materials, pencils, books, tools, wallets, keys, paperwork, eyeglasses, mobile telephones).
  8. Is often easily distracted by extraneous stimuli (for older adolescents and adults, may include unrelated thoughts).
  9. Is often forgetful in daily activities (e.g., doing chores, running errands; for older adolescents and adults, returning calls, paying bills, keeping appointments).
Note: The symptoms are not solely a manifestation of oppositional behaviour, defiance, hostility, or failure to understand tasks or instructions. For older adolescents and adults (age 17 and older), at least 5 symptoms are required.
Hyperactivity and Impulsivity

At least 6 of the following symptoms have persisted for at least 6 months to a degree that is inconsistent with developmental level and that negatively impacts directly on social and academic/occupational activities:

  1. Often fidgets with or taps hands or feet or squirms in seat.
  2. Often leaves seat in situations when remaining seated is expected (e.g. - leaves his or her place in the classroom, in the office or other workplace, or in other situations that require remaining in place).
  3. Often runs about or climbs in situations where it is inappropriate (Note: In adolescents or adults, may be limited to feeling restless.)
  4. Often unable to play or engage in leisure activities quietly
  5. Is often “on the go,” acting as if “driven by a motor” (e.g. - is unable to be or uncomfortable being still for extended time, as in restaurants, meetings; may be experienced by others as being restless or difficult to keep up with)
  6. Often talks excessively
  7. Often blurts out an answer before a question has been completed (e.g. - completes people’s sentences; cannot wait for turn in conversation).
  8. Often has difficulty waiting his or her turn (e.g. - while waiting in line)
  9. Often interrupts or intrudes on others (e.g. - butts into conversations, games, or activities; may start using other people’s things without asking or receiving per mission; for adolescents and adults, may intrude into or take over what others are doing).
Note: The symptoms are not solely a manifestation of oppositional behaviour, defiance, hostility, or a failure to understand tasks or instructions. For older adolescents and adults (age 17 and older), at least 5 symptoms are required.
Criterion B

Several inattentive or hyperactive-impulsive symptoms were present prior to age 12 years.

Criterion C

Several inattentive or hyperactive-impulsive symptoms are present in at least 2 settings (e.g. - home, school, work, with friends or relatives, in other activities).

Criterion D

There is clear evidence that the symptoms interfere with, or reduce the quality of, social, academic, or occupational functioning.

Criterion E

The symptoms do not occur exclusively during the course of schizophrenia or another psychotic disorder and are not better explained by another mental disorder.


When the child is inattentive, you CALL FOR FRED, this can be used to remember the inattention criteria. When the child is impulsive and hyperactive, he or she RUNS FASTT, this can be used to remember the hyperactivity-impulsivity criteria.[8]

Inattention Criteria

  • C - Careless mistakes
  • A - Attention difficulty
  • L - Listening problems
  • L - Loses things
  • F - Fails to finish what he/she starts
  • O - Organizational skills lacking
  • R - Reluctance to do tasks that need sustained mental effort
  • FR - Forgetful in routine activities
  • ED - Easily distracted

Hyperactivity-Impulsivity Criteria

  • R - Runs or is restless
  • U - Unable to wait for his or her turn
  • N - Not able to play quietly
  • S - Slow? – Oh no! He's on the go!
  • F - Fidgets with hands or feet
  • A - Answers blurted out
  • S - Staying seated is difficult
  • T - Talks excessively
  • T - Tends to interrupt

ADHD is likely overdiagnosed.[9][10][11][12][13] It is important to be aware of diagnostic creep and overdiagnosis! True ADHD is a debilitating condition that presents largely in childhood and absolutely should be treated. However, we are likely in a culture of overdiagnosis right now, especially with the ease of prescribing stimulants and short assessments in primary care settings. A short or incomplete assessment means a thorough differential diagnosis has not been considered! Since individuals both with and without ADHD can experience improved attention and decreased restlessness while taking stimulants, medication response alone is not a basis for diagnosing the disorder.[14] However, this is often a common diagnostic fallacy that many clinicians make.

Father of ADHD on Current Diagnosis and Treatment of the Condition

“The numbers make it look like an epidemic. Well, it’s not. It’s preposterous … This is a concoction to justify the giving out of medication at unprecedented and unjustifiable levels.”

– Dr. Keith Conners[15], child psychologist and father of the modern conceptualization of ADHD. New York Times: The Selling of Attention Deficit Disorder

Although many ADHD guidelines continue to suggest that prevalence rates are stable, and that overdiagnosis is not occurring, the epidemiological data is increasingly showing the opposite. A 2015 systematic review and meta-analysis (the most comprehensive to date) provided a conservative benchmark overall pooled estimate prevalence of 7.2% using 36 years of ADHD studies[16] In the United States, from 1997 to 2016, the estimated prevalence of diagnosed attention-deficit/hyperactivity disorder in US children and adolescents increased from 6.1% in 1997 to 10.2% in 2016.[17] This far exceeds the baseline estimated prevalence rates from the systematic review, suggesting that overdiagnosis may be occurring.

“If diagnoses from national or state population surveys exceed our estimate, then prima facie overdiagnosis of ADHD may be occurring for some children. If fewer, then underdiagnosis may be occurring.”[18]

Thomas, R., Sanders, S., Doust, J., Beller, E., & Glasziou, P. (2015). Prevalence of attention-deficit/hyperactivity disorder: a systematic review and meta-analysis. Pediatrics, 135(4), e994-e1001.
“Over the 20-year period, the estimated prevalence of diagnosed ADHD in US children and adolescents increased from 6.1% in 1997-1998 to 10.2% in 2015-2016 (P for trend <.001)”[19]

Xu, G., Strathearn, L., Liu, B., Yang, B., & Bao, W. (2018). Twenty-year trends in diagnosed attention-deficit/hyperactivity disorder among US children and adolescents, 1997-2016. JAMA network open, 1(4), e181471-e181471.
Adult ADHD

The most recent research has also called into question the validity of adult-onset ADHD diagnoses itself.[20] Once considered a rare condition, the prevalence of adult ADHD has increased significantly.[21]

Schools and Birth Month

Children, in particular boys, with summer birthdays (e.g. - August) entering kindergarten with a September 1st cut off date are more likely to have teachers who perceive them as having more behavioural or academic difficulties. As a result, immature but age-normal behaviours may be mistaken for ADHD symptoms. These youngest children have a 34% higher chance of an ADHD diagnosis and a 32% higher chance of ADHD treatment than children with a September birthday (i.e - children are 1 year older than them).

Misuse and Diversion

Consider also the role of stimulant misuse and diversion.[22][23] Long-term concurrent use of stimulants and opioids among adults with ADHD is common.[24]


Finally, consider also how the role of technology like smartphones and the Internet could be shaping and changing our attention spans.[25] [26][27] Our collective attention spans are getting shorter.[28]

  • Medication with cognitive dulling side effect
  • Medication with psychomotor activation
    • Think about decongestants and beta agonists
Other Factors
  • Unsafe or disruptive learning environment
  • Family dysfunction or poor parenting
  • Child abuse or neglect
General Medical Conditions
    • Since underlying ADHD can increase risk for head trauma, it is important to look for timing of cognitive symptoms apparition (present before, or appeared or worsened after head trauma).
  • Hearing impairment or vision impairment
    • Order audiology and vision assessment if there are any concerns
    • Order TSH levels to check for hypothyroidism or hyperthyroidism
  • Hypoglycemia
    • Check blood glucose levels
  • Anemia
    • Order CBC
  • Lead poisoning
    • Order blood lead levels
    • Molecular genetic testing for the FMR-1 gene confirms the diagnosis of Fragile X.
  • Phenylketonuria
  • Neurofibromatosis
  • Fetal alcohol spectrum disorder (FASD) and Intellectual disability
    • Consider the presence of intellectual disability and FASD by observing for growth deficiency and facial features and FASD. Ask a thorough developmental history around prenatal alcohol exposure risk. Further psychoeducational testing may also be helpful.

Recent research has shown that there are bilateral amygdala, accumbens, and hippocampus reductions in ADHD.[29] However, these findings have been scrutinized and remain under debate.[30][31] Like all psychiatric disorders, there is no single pathophysiological cause for ADHD.[32] ADHD diagnosis based on behavioural criteria that are sensitive to subjectivity and cognitive biases.

Stimulants and Risk of Psychosis

In adolescents and young adults with ADHD, the risk of new-onset psychosis occurs in approximately 1 in 660 patients, and amphetamine use is associated with a two-fold greater risk of psychosis than with methylphenidate.[33]

There is some evidence that supplementing diets of pediatric ADHD patients with fatty fish high in omega-3s or commercial preparations containing at least 500 mg of EPA can reduce symptoms.[34]

8) Child and Adolescent Psychiatry (Practical Guides in Psychiatry) 1st Edition, pg. 58, Dorothy Stubbe, MD