Attention-deficit/hyperactivity disorder (ADHD) is a fairly common disorder characterized by inattention, impulsivity and/or hyperactivity. It is estimated to affect 5-15% of school-aged children. There are three major subtypes: predominantly inattentive (pI), predominantly hyperactive-impulsive (pHI) and combined (C). The predominantly inattentive subtype is sometimes just called attention-deficit disorder (ADD). ADHD is usually treated with medications along with behavioural and education interventions. It is believed to be caused by reduced dopamine and noradrenergic activity in the prefrontal cortex (PFC), along with other brain abnormalities.[1]


For psychiatric disorders there are two major diagnostic manuals: the DSM-5 and ICD-10. ADHD is a term used in the DSM-5, but not the ICD-10. The ICD-10 instead describes a condition called hyperkinetic disorder[2] which is believed to be a more severe form of the disorder with combined features and affects significantly fewer children.[3]:26

Signs and symptomsEdit

Source: DSM-5.[4]

Either one of two features (or both features) are required: inattentive and/or hyperactivity/impulsive features. Inattentive features must persist for at least 6 months, must adversely affect education or work activities and include at least six of the following features:

  • Fails to give adequately close attention to details, or makes careless mistakes.
  • Has a short attention span (e.g., making it difficult to remain focused in class)
  • Being often seems distracted when spoken to directly, without an obvious cause.
  • Being often does not follow through on instructions and fails to complete tasks. For example they might forget to complete an assignment.
  • Disorganized work; leading to failing to meet deadlines, poor time management, keeping things in order, etc.
  • Avoids, dislikes or is reluctant to perform tasks that require sustained attention, like paperwork, reading long pages, school work or homework, etc.
  • Looses things required for day-to-day talks like glasses, mobile phones, paperwork, wallets, etc.
  • Easily distracted
  • Being often forgetful in daily activities like paying bills, doing chores, etc.

Hyperactive and impulsive features which includes (at least six of these features are required):

  • Excessive talking
  • Completes people's sentences or interrupts people while talking.
  • Restlessness manifesting, in children, as running around, or climbing inappropriately; in adolescents and adults it may be limited to feeling restless.
  • Leaving one's seat even when it is inappropriate
  • Unable to perform leisure activities quietly.
  • Being constantly, "On the go"
  • Being unable to wait in line
  • Often invades or interrupts others; for example they may butt into conversations, force themselves into games others are playing, they may start using an item without the owner's permission, etc.


Its exact cause is unknown, by various risk factors have been uncovered; including:[3]:28-29[5]

  • Family history of ADHD
  • Maternal (that is by the biological mother) smoking, alcohol consumption or the use of heroin during pregnancy
  • Exposure to lead and other poisonous chemicals
  • Fetal oxygen deprivation during pregnancy
  • Very low birth weight
  • Zinc deficiency


There are three major treatments: psychosocial interventions (like the talking approach, which can also involve the affected person's family or school interventions to help the affected person do well at school), dietary changes and medications. Psychosocial interventions are usually preferred in mild-moderate cases or in younger patients (that is children and adolescents). Medications are usually only used in severe cases, or where the affected person has a moderate case and refuses to/cannot participate in psychosocial inventions or where these interventions have been trialled and failed.[6][3]


Medications include stimulants, atomoxetine, antidepressants (although these agents are all off-label), alpha-2 adrenoceptor agonists and assorted others. All have advantages and disadvantages, sadly 30% of patients will fail to respond to stimulants.

Stimulants are generally regarded as the most effective drug treatments for ADHD, they include: dexamfetamine (dexamphetamine or dextroamphetamine; brand names: Dexedrine, Dextrostat and generics), dexmethylphenidate (brand name: Focalin), lisdexamfetamine (brand name: Elvanse, Vyvanse), metamfetamine (brand name: Desoxyn; only available in the U.S.A.; it is the most addictive of stimulants used in the treatment of ADHD), methylphenidate (brand names: Concerta, Equasym, Medikinet, Ritalin) and mixed amfetamine salts (brand name: Adderall).[5] They are all characterized by a rapid onset of action (within an hour usually), potential for abuse and addiction, similar side effect profiles, that often include:

  • Weight loss/growth stunting
  • Insomnia
  • Stomach pains
  • Dry mouth
  • Constipation
  • Headache
  • Dizziness
  • Nightmares
  • Restlessness
  • Nervousness
  • Irritability
  • Euphoria
  • Tremor
  • Sweating
  • Tachycardia
  • Palpitations
  • Heart attacks
  • Blood pressure changes[note 1]
  • Changes in sex drive
  • Impotence
  • Psychosis
  • Mania
  • Seizures
  • Stroke
  • Priapism

a comedown period may occur, with symptoms of fatigue and depression.

Amfetamines (everyone one of these have 'amfetamine' in their names) work by activating the TAAR1, hence inhibiting the noradrenaline and dopamine reuptake pumps, whilst simultaneously inhibiting VMAT2 hence directly inducing the release of these neurotransmitters into the synapse.[7][8] Methylphenidate and its d-isomer (dexmethylphenidate) work by inhibiting the reuptake of noradrenaline and dopamine.[3]:235

Atomoxetine (brand name: Strattera) works by serving as a noradrenaline reuptake inhibitor (NRI). The noradrenaline transporter is also present in areas of the brain (namely the prefrontal cortex) where the dopamine transporter is absent, despite the presence of the neurotransmitter dopamine, and it serves as the transporter for dopamine in these brain regions. Hence NRIs also increase dopamine concentrations in the PFC, without increasing dopamine concentrations in the reward centres of the brain, hence does not cause addiction or euphoria. Despite this it is plagued by a delayed onset of action of a few weeks, usually.[9]

Alpha-2 adrenoceptor agonists include clonidine (brand name: Catapres, Dixarit, Duraclon, Jenloga, Kapvay) and guanfacine (only available in the U.S.A., now; brand name: Intuniv, Tenex). They are very sedating (less of a problem with guanfacine) and often cause low blood pressure during early treatment (in fact they are both approved to treat hypertension), depression can also be a problem with them. With repeated treatment these side effects tend to subside but the delayed onset of action means they must be taken repeatedly for weeks and this can be problematic. See in Australia and the U.K. only immediate release formulations of clonidine, and as clonidine does not last in the body for very long this necessitates twice or three times daily dosing, which means that it can cause sedation during the rest of the day. In the U.S.A., an extended release formulation is available allowing once daily dosing.[3]:275-280[10] They can be either used alone or in combination with stimulants; the combination has been associated with sudden death,Cite error: Closing </ref> missing for <ref> tag.[11] despite this the combination has been found to more effective than either drug alone, however.[9] Guanfacine extended relase formulations have been found to be more effective than atomoxetine in a recent meta-analysis.[12]

Antidepressants used in the treatment of ADHD includes bupropion, desipramine, imipramine, nortriptyline and venlafaxine.[13][14] Bupropion is the most commonly used, although the evidence only supports its use in adults;[15] desipramine' is a tricyclic that's use is supported in children and adolescents but it is rarely used due to side effects and its toxicity in cases of overdose, it is only available in a handful of countries, with the only notable example being the U.S.A.;[16] imipramine is a tricyclic that is more sedating than desipramine, it can be used and is more widely available; nortriptyline is the least sedating tricyclic; venlafaxine's use is supported solely by small studies, hence its clinical use is generally advised against except in desperate circumstances.[17] Desipramine and nortripyline are tricyclic noradrenaline reuptake inhibitors; imipramine is a serotonin-noradrenaline reuptake inhibitor; venlafaxine is a serotonin-noradrenaline reuptake inhibitor; bupropion is a noradrenaline-dopamine reuptake inhibitor.

Modafinil has been used to treat ADHD, although its clinical use is generally advised against, based on serious skin reactions seen in clinical trials involving it.[15]

Dietary changesEdit

Dietary changes include consuming fish oils, which have been found to produce modest, yet significant improvements in ADHD symptoms, and removing certain artificial colours and flavours in those with insensitivities to these substances (which tends to produce fairly robust improvements in symptoms).[18]


Untreated ADHD is associated with an increased risk of overweight/obesity, substance abuse problems, criminal behaviour and antisocial personality disorder in adulthood.[19]:25-28 Treatment, especially with medications, is believed to reduce the risk of these complications.[20][21]


ADHD is believed to affect between 5-15% of school aged children; the predominantly inattentive form of the disorder affects both genders equally, whereas the predominantly hyperactive/impulsive subtype affects males far more commonly than females.[22] It is significantly more common in children than adults, most cases present before the age of 7; with age the rate of ADHD declines and many people that fulfilled the diagnostic criteria for the condition as children do not as adults.[3]:26-27

External linksEdit


  1. Usually increases but decreases also reported

Reference listEdit

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