attention deficit hyperactivity disorder (ADHD)
introduction
AD/HD consists of a pattern of behavior that is present in multiple settings where it gives rise to social, educational or work performance difficulties
it is a developmental disorder and it would appear over 99% have symptom onset prior to 7yrs of age, and most fit the criteria before age 3 yrs, although recall of such symptoms in adult life can be poor with only 50% recalling symptoms prior to age 7yrs while 95% can recall symptoms prior to age 12 years
it is now regarded as a persistent neurodevelopmental disorder impairing executive functioning (EF), or the “management system” of the brain, that usually persists into adulthood and can be an important co-morbid factor in adult psychiatric illnesses and substance abuse
it is estimated to affect 3-5% of children.
the gene Homer1 may have an important role in genetic variances in attention
a mouse study in 2025 found that reducing expression of Homer1 in prefrontal cortex neurons where attention is based, caused those cells to upregulate GABA receptors-the molecular brakes of the nervous system. This shift created a quieter baseline and more focused bursts of activity when cues appeared: instead of firing indiscriminately, neurons conserved their activity for moments that mattered, enabling more accurate responses.
1)
evolution of the diagnostic criteria
1st evidence of documention was in 1775 by Melchior Adam Weikard, a prominent German physician
the treatment of children with similar behavioral problems who had survived the epidemic of encephalitis lethargica from 1917 to 1918 and the pandemic of influenza from 1919 to 1920 led to terminology which referred to “brain damage” although this was later removed when it was realised many had this condition without evidence of brain damage.
DSM-II (1968) it was the “Hyperkinetic Reaction of Childhood”
research in the 1970s and 1980s began to show there are different types of attention deficit
DSM-III (1980) “ADD (Attention-Deficit Disorder) with or without hyperactivity” was introduced and specified a maximum age for its onset
in 1987 this was changed to ADHD in the DSM-III-R
DSM IV (1994) introduced ADHD with sub-types and added the criteria that impairment must be present prior to age 7 yrs not just symptoms
ICD-10 came into use 1994 after being ratified in 1990
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DSM V (2012 proposed) changed sub-types to “presentations” and increased age cut-off from 7yrs to 12yrs while changing age cut-off criteria from impairment to symptoms. These changes will thus increase the prevalence as it is more inclusive.
associations and sequeleae
adult sequelae
persistence of ADHD symptoms into adulthood varies:
adult symptoms usually relate to distractibility, impulsiveness, poor concentration, inability to persist at tasks, and difficulties with working memory, organization, and planning.
2)
often easily distracted by extraneous stimuli or irrelevant thoughts
often makes decisions impulsively
often has difficulty stopping activities or behaviors when they should do so
often starts a project or task without reading or listening to the directions carefully
often shows poor follow-through on promises or commitments made to others
often has trouble doing things in their proper order or sequence
often more likely to drive a motor vehicle much faster than others
often has difficulty engaging in leisure activities or doing fun things quietly
often has difficulty sustaining attention in tasks or play activities
often has difficulty organizing tasks and activities
significant impairment in social, educational, domestic (eg, dating, marriage, cohabitation, financial, driving, childrearing), occupational, or community functioning
3)
40-60% of adolescents with ADHD and 24-35% of clinically referred adults with criteria for ADHD also meeting criteria for Oppositional Defiant Disorder (ODD) and up to 25% meeting criteria for Conduct Disorder
many develop Antisocial Personality Disorder with higher risk of Substance Use Disorder (at least 2x the risk of adults without ADHD).
~25% of adults with drug dependence meet the ADHD criteria
~20% of adults with bipolar disorder, dysthymia or agoraphobia meet the ADHD criteria
13% of adults with social phobia or post-traumatic stress disorder meet the ADHD criteria
proposed DSM V criteria
age cut off increased to 12 years and only requires symptoms not impairment
“sub-types” changed to “presentations” in an attempt to make the classification more stable for an individual as it became evident that HT subtype children generally migrated to CT subtype as school demands increased.
4th “presentation added “restrictive”
item E has been modified to remove PDD
A
A1. Inattention
Six (or more) of the following symptoms have persisted for at least 6 months to a degree that is inconsistent with developmental level and that impact directly on social and academic/occupational activities.
a. 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).
b. Often has difficulty sustaining attention in tasks or play activities (e.g., has difficulty remaining focused during lectures, conversations, or reading lengthy writings).
d. 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; fails to finish schoolwork, household chores, or tasks in the workplace).
e. Often has difficulty organizing tasks and activities (e.g., difficulty managing sequential tasks; difficulty keeping materials and belongings in order; messy, disorganized, work; poor time management; tends to fail to meet deadlines).
f. 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, or reviewing lengthy papers).
g. Often loses things necessary for tasks or activities (e.g., school materials, pencils, books, tools, wallets, keys, paperwork, eyeglasses, or mobile telephones).
i. Is often forgetful in daily activities (e.g., chores, running errands; for older adolescents and adults, returning calls, paying bills, keeping appointments).
A2. Hyperactivity and Impulsivity
Six (or more) of the following symptoms have persisted for at least 6 months to a degree that is inconsistent with developmental level and that impact directly on social and academic/occupational activities.
hyperactivity
b. Often leaves seat in situations when remaining seated is expected (e.g., leaves his or her place in the classroom, office or other workplace, or in other situations that require remaining seated).
e. Is often “on the go,” acting as if “driven by a motor” (e.g., is unable or uncomfortable being still for an extended time, as in restaurants, meetings, etc; may be experienced by others as being restless and difficult to keep up with).
impulsivity
i. 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 permission, adolescents or adults may intrude into or take over what others are doing).
B
Several inattentive or hyperactive-impulsive symptoms were present prior to age 12. (in DSM IV the age criteria was 7 years, and evidence of impairment was required)
over 96% of cases are captured by age 12-14 yr cut-off
as adults, only 50% can recall what they were like before age 7yrs while 95% can recall behaviour prior to 12 years
age 7yrs had no validity and excluded valid cases
the DSM IV additional criteria of requiring impairment had little evidence to support it
this criteria only requiring symptoms and not impairment is more consistent with ICD, and a requirement for impairment would create issues with assessment of this, and variation of school standards
in the study by Applegate et al in 1997, whilst nearly all youths who met symptom criteria for HT also met the impairment criteria before age 7yrs, only 18% of those with CT and 43% of those with IT did so.
C
Criteria for the disorder are met in two or more settings (e.g., at home, school or work, with friends or relatives, or in other activities).
D
There must be clear evidence that the symptoms interfere with or reduce the quality of social, academic, or occupational functioning.
E
The symptoms do not occur exclusively during the course of schizophrenia or another psychotic disorder and are not better accounted for by another mental disorder (e.g., mood disorder, anxiety disorder, dissociative disorder, or a personality disorder).
Specify Based on Current Presentation
Combined Presentation:
Predominantly Inattentive Presentation:
If Criterion A1 (Inattention) is met but Criterion A2 (Hyperactivity-Impulsivity) is not met and 3 or more symptoms from Criterion A2 have been present for the past 6 months.
formerly Predominantly Inattentive Type (IT)
Inattentive Presentation (Restrictive):
Predominantly Hyperactive/Impulsive Presentation:
pharmacologic Rx
Australian PBS approved medications for Rx of ADHD
dexamphetamine
clonidine (Catapres®), an alpha-2 noradrenergic agonist, is sometimes prescribed to reduce persisting aggression and hyperactivity in children with ADHD, or for children with ADHD who are experiencing sleep disturbances.
Ritalin®, a short-acting methylphenidate was added in August 2005
Attenta®, a cheaper short-acting methylphenidate formulation was added in December 2005 but discontinued in November 2008
Concerta®, an extended release formulation of methylphenidate was added in April 2007
Strattera®, atomoxetine, is the only non-stimulant medication approved for ADHD and was listed on PBS July 2007
Ritalin LA®, an extended release formulation of methylphenidate was added in April 2008
NB. authority for the extended release forms is only available to those between 6-18 yrs age, whilst authority of the short-acting formulations are subject to prescription in accordance with local State/Territorial laws.