Attention deficit hyperactivity disorder ( ADHD) is a neurodevelopmental disorder characterised by symptoms of inattention, hyperactivity, impulsivity, and emotional dysregulation that are excessive and pervasive, impairing in multiple contexts, and developmentally inappropriate. ADHD symptoms arise from executive dysfunction.
Impairments resulting from deficits in self-regulation such as time management, inhibition, task initiation, and sustained attention can include poor professional performance, relationship difficulties, and numerous health risks, collectively predisposing to a diminished quality of life and a reduction in life expectancy. As a consequence, the disorder costs society hundreds of billions of US dollars each year, worldwide. It is associated with other as well as non-psychiatric disorders, which can cause additional impairment.
While ADHD involves a lack of sustained attention to tasks, inhibitory deficits also can lead to difficulty interrupting an already ongoing response pattern, manifesting in the perseveration of actions despite a change in context whereby the individual intends the termination of those actions. This symptom is known colloquially as hyperfocus and is related to risks such as addiction and types of offending behaviour. ADHD can be difficult to tell apart from other conditions. ADHD represents the extreme lower end of the continuous dimensional trait (bell curve) of executive functioning and self-regulation, which is supported by twin, brain imaging and molecular genetic studies.
The precise causes of ADHD are unknown in most individual cases. Meta-analyses have shown that the disorder is primarily genetic with a heritability rate of 70–80%, where risk factors are highly accumulative. The environmental risks are not related to social or familial factors; they exert their effects very early in life, in the prenatal or early postnatal period. However, in rare cases, ADHD can be caused by a single event including traumatic brain injury, exposure to biohazards during pregnancy, or a major genetic mutation. As it is a neurodevelopmental disorder, there is no biologically distinct adult-onset ADHD except for when ADHD occurs after traumatic brain injury.
According to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and its text revision (DSM-5-TR), symptoms must be present for six months or more to a degree that is much greater than others of the age appropriate. This requires at least six symptoms of either inattention or hyperactivity/impulsivity for those under 17 and at least five symptoms for those 17 years or older. The symptoms must be present in at least two settings (e.g., social, school, work, or home), and must directly interfere with or reduce quality of functioning. Additionally, several symptoms must have been present before age 12 as per DSM-5 criteria. However, research indicates the age of onset should not be interpreted as a prerequisite for diagnosis given contextual exceptions.
The table "Symptoms" lists the symptoms for ADHD-I and ADHD-HI from two major classification systems. Symptoms which can be better explained by another psychiatric or medical condition which an individual has are not considered to be a symptom of ADHD for that person. In DSM-5, subtypes were discarded and reclassified as presentations of the disorder that change over time.
The individual may also meet the criteria for hyperactivity-impulsivity, but the inattentive symptoms are predominant.
The individual may also meet the criteria for inattention, but the hyperactive-impulsive symptoms are predominant.
Girls and women with ADHD tend to display fewer hyperactivity and impulsivity symptoms but more symptoms of inattention and distractibility.
Symptoms are expressed differently and more subtly as the individual ages. Hyperactivity tends to become less overt with age and turns into inner restlessness, difficulty relaxing or remaining still, talkativeness or constant mental activity in teens and adults with ADHD. Impulsivity in adulthood may appear as thoughtless behaviour, impatience, irresponsible spending and sensation-seeking behaviours, while inattention may appear as becoming easily bored, difficulty with organisation, remaining on task and making decisions, and sensitivity to stress.
A state of hyperfocus has been hypothesised as being beneficial, allowing individuals to focus on tasks for much longer than is typical. Conversely, it can be difficult to disengage from and shift attention to other stimuli or tasks, leading to excessively prolonged attention. It is related to risks such as internet addiction (see ) and to some types of offending behaviour. Recent research has linked hyperfocus to the psychological concepts of flow, an enjoyable experience of deep engagement in an activity, and perseveration, difficulty disengaging or switching from an activity.
Studies of adults suggest that negative differences in intelligence are not meaningful and may be explained by associated health problems.
Genetic factors play an important role; ADHD has a heritability rate of 70–80%. The remaining 20–30% of variance is mediated by de-novo mutations and non-shared environmental factors that provide for or produce brain injuries; there is no significant contribution of the rearing family and social environment. Very rarely, ADHD can also be the result of abnormalities in the chromosomes.
Natural selection has been acting against some genetic variants for ADHD over the course of at least 45,000 years, complicating the suggestion that ADHD was an adaptive form of neurodiversity in the human evolutionary past. The disorder may remain at a stable rate by the balance of genetic mutations and removal rate (natural selection) across generations; over thousands of years, these genetic variants become more stable, decreasing disorder prevalence. Throughout human evolution, the executive functions involved in ADHD likely provide the capacity to bind contingencies across time thereby directing behaviour toward future over immediate events so as to maximise future social consequences for humans.
ADHD has a high heritability of 74%, meaning that 74% of the presence of ADHD in the population is due to genetic factors. There are multiple gene variants which each slightly increase the likelihood of a person having ADHD; it is polygenic and thus arises through the accumulation of many genetic risks each having a very small effect. The siblings of children with ADHD are three to four times more likely to develop the disorder than siblings of children without the disorder.
The association of maternal smoking observed in large population studies disappears after adjusting for family history of ADHD, which indicates that the association between maternal smoking during pregnancy and ADHD is due to familial or genetic factors that increase the risk for the confluence of smoking and ADHD.
ADHD presents with reduced size, functional connectivity and activation as well as low noradrenergic and dopaminergic functioning in brain regions and networks crucial for executive functioning and self-regulation. Typically, a number of genes are involved, many of which directly affect brain functioning and neurotransmission. Those involved with dopamine include DAT, DRD4, DRD5, TAAR1, MAOA, COMT, and DBH. Other genes associated with ADHD include SERT, HTR1B, SNAP25, GRIN2A, ADRA2A, TPH2, and BDNF. A common variant of a gene called latrophilin 3 is estimated to be responsible for about 9% of cases and when this variant is present, people are particularly responsive to stimulant medication. The 7 repeat variant of dopamine receptor D4 (DRD4–7R) causes increased inhibitory effects induced by dopamine and is associated with ADHD. The DRD4 receptor is a G protein-coupled receptor that inhibits adenylyl cyclase. The DRD4–7R mutation results in a wide range of behavioural , including ADHD symptoms reflecting split attention. The DRD4 gene is both linked to novelty seeking and ADHD. The genes GFOD1 and T-cadherin show strong genetic associations with ADHD. CDH13's association with Autism Spectrum Disorder (ASD), schizophrenia, bipolar disorder, and depression make it an interesting candidate causative gene. Another candidate causative gene that has been identified is ADGRL3. In zebrafish, knockout of this gene causes a loss of dopaminergic function in the ventral diencephalon and the fish display a hyperactive/impulsive phenotype.
For genetic variation to be used as a tool for diagnosis, more validating studies need to be performed. However, smaller studies have shown that genetic polymorphisms in genes related to catecholaminergic neurotransmission or the SNARE complex of the synapse can reliably predict a person's response to Stimulant. Rare genetic variants show more relevant clinical significance as their penetrance (the chance of developing the disorder) tends to be much higher. However their usefulness as tools for diagnosis is limited as no single gene predicts ADHD. ASD shows genetic overlap with ADHD at both common and rare levels of genetic variation.
Extreme premature birth, very low birth weight, and extreme neglect, abuse, or social deprivation also increase the risk as do certain infections during pregnancy, at birth, and in early childhood. These infections include, among others, various viruses (measles, varicella zoster encephalitis, rubella, enterovirus 71). At least 30% of children with a traumatic brain injury later develop ADHD and about 5% of cases are due to brain damage.
Some studies suggest that in a small number of children, artificial or preservatives may be associated with an increased prevalence of ADHD or ADHD-like symptoms, but the evidence is weak and may apply to only children with food sensitivities. The European Union has put in place regulatory measures based on these concerns. In a minority of children, food intolerance or food allergy to certain foods may worsen ADHD symptoms.
Individuals with hypokalemic sensory overstimulation are sometimes diagnosed as having ADHD, raising the possibility that a subtype of ADHD has a cause that can be understood mechanistically and treated in a novel way. The sensory overload is treatable with oral potassium gluconate.
Research does not support popular beliefs that ADHD is caused by eating too much refined sugar, watching too much television, bad parenting, poverty or family chaos; however, they might worsen ADHD symptoms in certain people.
Children who enter school earlier and are of a younger age than their classmates are more likely to have educational and behavioral problems than their peers, which can make them more likely to be diagnosed with ADHD. Behaviours typical of ADHD occur more commonly in children who have experienced violence and emotional abuse.
The subcortical volumes of the accumbens, amygdala, Caudate nucleus, hippocampus, and putamen appears smaller in individuals with ADHD compared with controls. Structural MRI studies have also revealed differences in white matter, with marked differences in inter-hemispheric asymmetry between ADHD and typically developing youths.
Functional MRI (fMRI) studies have revealed a number of differences between ADHD and control brains. Mirroring what is known from structural findings, fMRI studies have shown evidence for a higher connectivity between subcortical and cortical regions, such as between the caudate and prefrontal cortex. The degree of hyperconnectivity between these regions correlated with the severity of inattention or hyperactivity Hemispheric lateralisation processes have also been postulated as being implicated in ADHD, but empiric results showed contrasting evidence on the topic.
PET mapping of neocortex receptor distribution indicates that the distribution of μ-opioid receptors is the strongest contributor to cortical abnormalities in ADHD, followed by CB1 cannabinoid receptors.
ADHD has also been associated with motivational deficits in children. Children with ADHD often find it difficult to focus on long-term over short-term rewards, and exhibit impulsive behaviour for short-term rewards.
The diagnosis of ADHD has been criticised as being subjective because it is not based on a biological test. The International Consensus Statement on ADHD concluded that this criticism is unfounded, on the basis that ADHD meets standard criteria for validity of a mental disorder established by Robins and Guze. They attest that the disorder is considered valid because: 1) well-trained professionals in a variety of settings and cultures agree on its presence or absence using well-defined criteria and 2) the diagnosis is useful for predicting a) additional problems the patient may have (e.g., difficulties learning in school); b) future patient outcomes (e.g., risk for future drug abuse); c) response to treatment (e.g., medications and psychological treatments); and d) features that indicate a consistent set of causes for the disorder (e.g., findings from genetics or brain imaging), and that professional associations have endorsed and published guidelines for diagnosing ADHD.
The most commonly used rating scales for diagnosing ADHD in children are the Achenbach System of Empirically Based Assessment (ASEBA) and include the Child Behavior Checklist (CBCL) used for parents to rate their child's behaviour, the Youth Self Report Form (YSR) used for children to rate their own behaviour, and the Teacher Report Form (TRF) used for teachers to rate their pupil's behaviour. Additional rating scales that have been used alone or in combination with other measures to diagnose ADHD include the Behavior Assessment System for Children (BASC), Behavior Rating Inventory of Executive Function - Second Edition (BRIEF2), Revised Conners Rating Scale (CRS-R), Conduct-Hyperactive-Attention Problem-Oppositional Symptom scale (CHAOS), Developmental Behavior Checklist Hyperactivity Index (DBC-HI), Parent Disruptive Behavior Disorder Ratings Scale (DBDRS), Diagnostic Infant and Preschool Assessment (DIPA-L), Pediatric Symptom Checklist (PSC), Social Communication Questionnaire (SCQ), Social Responsiveness Scale (SRS), Strengths and Weaknesses of ADHD Symptoms and Normal Behavior Rating Scale (SWAN) and the Vanderbilt ADHD diagnostic rating scale.
The ASEBA, BASC, CHAOS, CRS, and Vanderbilt diagnostic rating scales allow for both parents and teachers as raters in the diagnosis of childhood and adolescent ADHD. Adolescents may also self report their symptoms using self report scales from the ASEBA, SWAN, and the Dominic Interactive for Adolescents-Revised (DIA-R). Self-rating scales, such as the ADHD rating scale and the Vanderbilt ADHD diagnostic rating scale, are used in the screening and evaluation of ADHD.
Based on a 2024 systematic literature review and meta analysis commissioned by the Patient-Centered Outcomes Research Institute (PCORI), rating scales based on parent report, teacher report, or self-assessment from the adolescent have high internal consistency as a diagnostic tool meaning that the items within the scale are highly interrelated. The reliability of the scales between raters (i.e. their degree of agreement) however is poor to moderate making it important to include information from multiple raters to best inform a diagnosis.
Imaging studies of the brain do not give consistent results between individuals; thus, they are only used for research purposes and not a diagnosis. Electroencephalography is not accurate enough to make an ADHD diagnosis. A 2024 systematic review concluded that the use of such as blood or urine samples, electroencephalogram (EEG) markers, and neuroimaging such as MRIs, in diagnosis for ADHD remains unclear; studies showed great variability, did not assess test-retest reliability, and were not independently replicable.
In North America and Australia, DSM-5 criteria are used for diagnosis, while European countries usually use the ICD-11 criteria. ADHD is alternately classified as neurodevelopmental disorder or a disruptive behaviour disorder along with ODD, Conduct disorder, and antisocial personality disorder. A diagnosis does not imply a neurological disorder.
Very few studies have been conducted on diagnosis of ADHD on children younger than 7 years of age, and those that have were found in a 2024 systematic review to be of low or insufficient strength of evidence. A 2024 systematic review commissioned by the Patient-Centered Outcomes Research Institute (PCORI) highlighted that although a variety of diagnostic approaches show potential, there is substantial variability in their performance across studies. The CBCL and Disruptive Behavior Diagnostic Observation Schedule (DB-DOS) showed good performance, while BRIEF worked very well. However, there is not enough studies on children younger than 7 years of age to determine which diagnosis method is the most effective. The review emphasised that diagnostic accuracy often depends on the comparison group—whether children with ADHD are being distinguished from typically developing peers or from other clinically referred youth—and that multiple informants (such as parents, teachers, and the youth themselves) may be necessary to improve diagnostic accuracy due to poor-to-moderate agreement between raters.
This subdivision is based on presence of at least six (in children) or five (in older teenagers and adults) out of nine long-term (lasting at least six months) symptoms of inattention, hyperactivity–impulsivity, or both. To be considered, several symptoms must have appeared by the age of six to twelve and occur in more than one environment (e.g. at home and at school or work). The symptoms must be inappropriate for a child of that age and there must be clear evidence that they are causing impairment in multiple domains of life.
The DSM-5 and the DSM-5-TR also provide two diagnoses for individuals who have symptoms of ADHD but do not entirely meet the requirements. Other Specified ADHD allows the clinician to describe why the individual does not meet the criteria, whereas Unspecified ADHD is used where the clinician chooses not to describe the reason.
In the tenth revision (ICD-10), the symptoms of hyperkinetic disorder were analogous to ADHD in the ICD-11. When a conduct disorder (as defined by ICD-10) is present, the condition was referred to as hyperkinetic conduct disorder. Otherwise, the disorder was classified as disturbance of activity and attention, other hyperkinetic disorders or hyperkinetic disorders, unspecified. The latter was sometimes referred to as hyperkinetic syndrome.
Worldwide, it is estimated that 2.58% of adults have persistent ADHD (where the individual currently meets the criteria and there is evidence of childhood onset), and 6.76% of adults have symptomatic ADHD (meaning that they currently meet the criteria for ADHD, regardless of childhood onset). In 2020, this was 139.84 million and 366.33 million affected adults respectively. Around 15% of children with ADHD continue to meet full DSM-IV-TR criteria at 25 years of age, and 50% still experience some symptoms. , most adults remain untreated. Many adults with ADHD without diagnosis and treatment have a disorganised life, and some use Substance abuse or Alcoholism as a coping mechanism. Other problems may include relationship and job difficulties, and an increased risk of criminal activities. Associated mental health problems include depression, anxiety disorders, and learning disabilities.
Some ADHD symptoms in adults differ from those seen in children. While children with ADHD may climb and run about excessively, adults may experience an inability to relax, or may talk excessively in social situations. Adults with ADHD may start relationships impulsively, display sensation-seeking behaviour, and be short-tempered. Addictive behaviour such as substance abuse and gambling are common. Previously, changes in ADHD presentation over time led to those diagnosed as children appearing to have outgrown the DSM-IV criteria. The DSM-5 addresses this issue by differentiating childhood and adult diagnostic criteria, a marked departure from the DSM-IV, which did not fully take into account the differences in impairments seen in adulthood compared to childhood.
For diagnosis in an adult, the presence of symptoms since childhood is generally required. However, a proportion of adults who meet the criteria for ADHD in adulthood would not have been diagnosed with ADHD as children. Most cases of late-onset ADHD develop the disorder between the ages of 12–16 and may therefore be considered early adult or adolescent-onset ADHD.
The DSM provides differential diagnoses – potential alternate explanations for specific symptoms. Assessment and investigation of clinical history determines which is the most appropriate diagnosis. The DSM-5 suggests oppositional defiant disorder, intermittent explosive disorder, and other disorders such as stereotypic movement disorder and Tourette syndrome, in addition to specific learning disorder, intellectual disability, autism, reactive attachment disorder, , depressive disorders, bipolar disorder, disruptive mood dysregulation disorder, substance use disorder, personality disorders, psychotic disorders, medication-induced symptoms, and neurocognitive disorders. Many but not all of these are also common comorbidities of ADHD. The DSM-5-TR also suggests post-traumatic stress disorder.
Symptoms of ADHD that particularly relate to disinhibition and irritability in addition to low-mood and self-esteem as a result of symptom expression might be confusable with dysthymia and bipolar disorder as well as with borderline personality disorder, however they are comorbid at a significantly increased rate relative to the general population. Some symptoms that are viewed superficially due to anxiety disorders, intellectual disability or the effects of substance abuse such as intoxication and Drug withdrawal can overlap to some extent with ADHD symptoms. These disorders can also occur along with ADHD.
Primary sleep disorders may affect attention and behaviour and the symptoms of ADHD may affect sleep. It is thus recommended that children with ADHD be regularly assessed for sleep problems. Sleepiness in children may result in symptoms ranging from the classic ones of yawning and rubbing the eyes, to disinhibition and inattention. Obstructive sleep apnea can also cause ADHD-like symptoms.
In general, the DSM-5-TR can help distinguish between many conditions associated with ADHD-like symptoms by the context in which the symptoms arise. For example, children with learning disabilities may feel distractable and agitated when asked to engage in tasks that require the impaired skill (e.g., reading, math), but not in other situations. A person with an intellectual disability may develop symptoms that overlap with ADHD when placed in a school environment that is inappropriate for their needs. The type of inattention implicated in ADHD, of poor persistence and sustained attention, differs substantially from selective or oriented inattention seen in cognitive disengagement syndrome (CDS), as well as from rumination, reexperiencing or mind blanking seen in anxiety disorders or PTSD.
In mood disorders, ADHD-like symptoms may be limited to Mania or depressive states of an episodic nature. Symptoms overlapping with ADHD in psychotic disorders may be limited to psychotic states. Substance use disorder, some medications, and certain medical conditions may cause symptoms to appear later in life, while ADHD, as a neurodevelopmental disorder, requires for them to have been present since childhood.
Furthermore, a careful understanding of the nature of the symptoms may help establish the difference between ADHD and other disorders. For example, the forgetfulness and impulsivity typical of ADHD (e.g., in completing school assignments or following directions) may be distinguished from opposition when there is no hostility or defiance, although ADHD and ODD are highly comorbid. Tantrums may differ from the outbursts in intermittent explosive disorder if there is no aggression involved. The fidgetiness observed in ADHD may be differentiated from or Stereotypy common in Tourette syndrome or autism.
Also, the social difficulties often experienced by individuals with ADHD due to inattention (e.g., being unfocused during the interaction and therefore missing cues or being unaware of one's behavior) or impulsivity (blurting things out, asking intrusive questions, interrupting) may be contrasted with the social detachment and deficits in understanding social cues associated with Autism Spectrum Disorder. Individuals with ADHD may also present signs of the social impairment or emotional and cognitive dysregulation seen in personality disorders, but not necessarily such features as a fear of abandonment, an unstable sense of self, narcissistic tendencies, aggressiveness, or other personality features.
While it is possible and common for many of these different conditions to be comorbid with ADHD, the symptoms must not be better explained by them, as per diagnostic criterion E in the DSM-5. The symptoms must arise early in life, appear across multiple environments, and cause significant impairment. Moreover, when some of these conditions are in fact comorbid with ADHD, it is still important to distinguish them, as each may need to be treated separately.
Other neurodevelopmental conditions are common comorbidities. Autism spectrum disorder (ASD), co-occurring at a rate of 21% in those with ADHD, affects social skills, ability to communicate, behaviour, and interests. Learning disabilities have been found to occur in about 20–30% of children with ADHD. Learning disabilities can include developmental speech and language disorders, and academic skills disorders. ADHD, however, is not considered a learning disability, but it very frequently causes academic difficulties. Intellectual disabilities and Tourette syndrome are also common.
ADHD is often comorbid with disruptive, impulse control, and conduct disorders. Oppositional defiant disorder (ODD) occurs in about 25% of children with an inattentive presentation and 50% of those with a combined presentation. It is characterised by angry or irritable mood, argumentative or defiant behaviour and vindictiveness which are age-inappropriate. Conduct disorder (CD) is another common comorbid disorder of adolescents with ADHD, and occurs in 25% of individuals with combined presentation. It is characterised by aggression, destruction of property, deceitfulness, theft and violations of rules. Adolescents with ADHD who also have CD are more likely to develop antisocial personality disorder in adulthood. Brain imaging supports that CD and ADHD are separate conditions: conduct disorder was shown to reduce the size of one's Temporal lobe lobe and limbic system, and increase the size of one's orbitofrontal cortex, whereas ADHD was shown to reduce connections in the cerebellum and prefrontal cortex more broadly. Conduct disorder involves more impairment in motivation control than ADHD. Intermittent explosive disorder is characterised by sudden and disproportionate outbursts of anger and co-occurs in individuals with ADHD more frequently than in the general population.
Borderline personality disorder has also been noted to co-occur with ADHD, though more recent research suggests this may be due to historical biases leading to misdiagnoses. The current diagnostic assessment of either disorder is often complex, as both of them have overlapping symptoms, thus these assessments often follow a differential diagnosis (following the American Psychiatric Association Guidelines for diagnosis) to determine whether there's a co-occurrence of both disorders or not.
Anxiety and mood disorders are frequent comorbidities. have been found to occur more commonly in the ADHD population, as have (especially bipolar disorder and major depressive disorder). While boys tend to present with comorbidities that involve externalization, girls tend to internalize their symptoms, leading to the possibility of increased misdiagnosis via standards designed to recognize male ADHD. Adults and children with ADHD sometimes also have bipolar disorder, which requires careful assessment to accurately diagnose and treat both conditions.
Sleep disorders and ADHD commonly co-exist. They can also occur as a side effect of medications used to treat ADHD. In children with ADHD, insomnia is the most common sleep disorder with behavioural therapy being the preferred treatment. Problems with sleep initiation are common among individuals with ADHD but often they will be deep sleepers and have significant difficulty getting up in the morning. Melatonin is sometimes used in children who have sleep onset insomnia. Restless legs syndrome has been found to be more common in those with ADHD and is often due to iron deficiency anemia. However, restless legs can simply be a part of ADHD and requires careful assessment to differentiate between the two disorders. Delayed sleep phase disorder is also a common comorbidity.
Individuals with ADHD are at increased risk of substance use disorders. This is most commonly seen with alcohol or cannabis. The reason for this may be an altered reward pathway in the brains of ADHD individuals, self-treatment and increased psychosocial risk factors. This makes the evaluation and treatment of ADHD more difficult, with serious substance misuse problems usually treated first due to their greater risks. Other psychiatric conditions include reactive attachment disorder, characterised by a severe inability to appropriately relate socially, and cognitive disengagement syndrome, a distinct attention disorder occurring in 30–50% of ADHD cases as a comorbidity, regardless of the presentation; a subset of cases diagnosed with ADHD-PIP have been found to have CDS instead. Individuals with ADHD are three times more likely to be diagnosed with an eating disorder compared to those without ADHD; conversely, individuals with eating disorders are two times more likely to have ADHD than those without eating disorders.
A 2021 review reported that several neurometabolic disorders caused by inborn errors of metabolism converge on common neurochemical mechanisms that interfere with biological mechanisms also considered central in ADHD pathophysiology and treatment. This highlights the importance of close collaboration between health services to avoid clinical overshadowing.
In June 2021, Neuroscience & Biobehavioral Reviews published a systematic review of 82 studies that all confirmed or implied elevated accident-proneness in ADHD patients, and whose data suggested that the type of accidents or injuries—and overall risk—changes over the lifespan of ADHD patients. In January 2014, Accident Analysis & Prevention published a meta-analysis of 16 studies examining the relative risk of traffic collisions for drivers with ADHD, finding an overall relative risk estimate of 1.36 without controlling for exposure, a relative risk estimate of 1.29 when controlling for publication bias, a relative risk estimate of 1.23 when controlling for exposure, and a relative risk estimate of 1.86 for ADHD drivers with oppositional defiant disorder or conduct disorder Comorbidity.
There is little high-quality research on the effectiveness of family therapy for ADHD—but the existing evidence shows that it is similar to community care, and better than placebo. ADHD-specific support groups can provide information and may help families cope with ADHD.
Social skills training, behavioural modification, and medication may have some limited beneficial effects in peer relationships. Stable, high-quality friendships with non-deviant peers protect against later psychological problems.
In addition to pediatric populations, a 2023 study in the Journal of the American Academy of Child & Adolescent Psychiatry investigated the efficacy and safety of AKL-T01 in adults with ADHD. After six weeks of at-home treatment with AKL-T01, participants showed significant improvements in objective measures of attention (TOVA - Attention Comparison Score), reported ADHD symptoms (ADHD-RS-IV inattention subscale and total score), and reported quality of life (AAQoL). The magnitude of improvement in attention was nearly seven times greater than that reported in pediatric trials. The treatment was well-tolerated, with high compliance and no serious adverse events.
Safety and efficacy data have been reviewed extensively by medical regulators (e.g., the US Food and Drug Administration and the European Medicines Agency), the developers of evidence-based international guidelines (e.g., the UK National Institute for Health and Care Excellence and the American Academy of Pediatrics), and government agencies who have endorsed these guidelines (e.g., the Australian National Health and Medical Research Council). These professional groups unanimously conclude, based on the scientific evidence, that methylphenidate is safe and effective and should be considered as a first-line treatment for ADHD.
The likelihood of developing insomnia for ADHD patients taking stimulants has been measured at between 11 and 45 per cent for different medications, and may be a main reason for discontinuation. Other side effects, such as , decreased appetite and weight loss, or emotional lability, may also lead to discontinuation. Stimulant psychosis and mania are rare at therapeutic doses, appearing to occur in approximately 0.1% of individuals, within the first several weeks after starting amphetamine therapy. The safety of these medications in pregnancy is unclear. Symptom improvement is not sustained if medication is ceased.
The long-term effects of ADHD medication have yet to be fully determined, although stimulants are generally beneficial and safe for up to two years for children and adolescents. A 2022 meta-analysis found no statistically significant association between ADHD medications and the risk of cardiovascular disease (CVD) across age groups, although the study suggests further investigation is warranted for patients with preexisting CVD as well as long-term medication use. Regular monitoring has been recommended in those on long-term treatment. There are indications suggesting that stimulant therapy for children and adolescents should be stopped periodically to assess continuing need for medication, decrease possible growth delay, and reduce tolerance. Although potentially addictive at high doses,
The majority of studies on nicotine and other nicotinic agonists as treatments for ADHD have shown favorable results; however, no nicotinic drug has been approved for ADHD treatment. Caffeine was formerly used as a second-line treatment for ADHD but research indicates it has no significant effects in reducing ADHD symptoms. Caffeine appears to help with alertness, arousal and reaction time but not the type of inattention implicated in ADHD (sustained attention/persistence). Pseudoephedrine and ephedrine do not affect ADHD symptoms.
Modafinil has shown some efficacy in reducing the severity of ADHD in children and adolescents. It may be prescribed off-label to treat ADHD.
Atomoxetine, due to its lack of addiction liability, may be preferred in those who are at risk of recreational or compulsive stimulant use, although evidence is lacking to support its use over stimulants for this reason. Atomoxetine alleviates ADHD symptoms through norepinephrine reuptake and by indirectly increasing dopamine in the pre-frontal cortex, sharing 70–80% of the brain regions with stimulants in their produced effects. Atomoxetine has been shown to significantly improve academic performance. Meta-analysis and systematic reviews have found that atomoxetine has comparable efficacy, equal tolerability and response rate (75%) to methylphenidate in children and adolescents. In adults, efficacy and discontinuation rates are equivalent.
Analyses of clinical trial data suggests that viloxazine is about as effective as atomoxetine and methylphenidate but with fewer side effects.
Amantadine was shown to induce similar improvements in children treated with methylphenidate, with less frequent side effects. A 2021 retrospective study showed that amantadine may serve as an effective adjunct to stimulants for ADHD–related symptoms and appears to be a safer alternative to second- or third-generation antipsychotics.
Bupropion is also used off-label by some clinicians due to research findings. It is effective, but modestly less than atomoxetine and methylphenidate.
There is little evidence on the effects of medication on social behaviours. Antipsychotics may also be used to treat aggression in ADHD.
Alpha-2a agonists
Two alpha-2a agonists, extended-release formulations of guanfacine and clonidine, are approved by the FDA and in other countries for the treatment of ADHD (effective in children and adolescents but effectiveness has still not been shown for adults). They appear to be modestly less effective than the stimulants (amphetamine and methylphenidate) and non-stimulants (atomoxetine and viloxazine) at reducing symptoms, but can be useful alternatives or used in conjunction with a stimulant. These medications act by adjusting the alpha-2a ports on the outside of noradrenergic nerve cells in the pre-frontal executive networks, so the information (electrical signal) is less confounded by noise.
Chronic deficiencies of iron, magnesium and iodine may have a negative impact on ADHD symptoms. There is a small amount of evidence that lower tissue zinc levels may be associated with ADHD. In the absence of a demonstrated zinc deficiency (which is rare outside of developing countries), zinc supplementation is not recommended as treatment for ADHD. However, zinc supplementation may reduce the minimum effective dose of amphetamine when it is used with amphetamine for the treatment of ADHD.
The negative impacts of ADHD symptoms contribute to poor health-related quality of life that may be further exacerbated by, or may increase the risk of, other psychiatric conditions such as anxiety and depression. Individuals with ADHD may also face misconceptions and stigma. A number of recent studies have found that ADHD is associated with a significant reduction in average life expectancy. A US study found rates of smoking among those with ADHD are higher than in the general population. Positive effects of medication on functional impairment and quality of life (e.g. reduced risk of accidents) have been found across multiple domains.
Individuals with ADHD are significantly overrepresented in prison populations. Although there is no generally accepted estimate of ADHD prevalence among inmates, a 2015 meta-analysis estimated a prevalence of 25.5%, and a larger 2018 meta-analysis estimated the frequency to be 26.2%.
New research in 2025 indicates that adults diagnosed with ADHD may have a shorter lifespan compared to those without the condition. The study revealed that, on average, men with ADHD lived seven years less than men without ADHD, while women with ADHD had a lifespan nine years shorter than their peers. Although the study did not pinpoint exact causes of death, it highlighted that individuals with ADHD were more likely to engage in smoking, Alcohol abuse, and face other health challenges such as depression, self-harm, or personality disorders.
ADHD is diagnosed approximately twice as often in boys as in girls, and 1.6 times more often in men than in women, although the disorder is overlooked in girls or diagnosed in later life because their symptoms sometimes differ from diagnostic criteria. In 2014, Keith Conners, one of the early advocates for recognition of the disorder, spoke out against overdiagnosis in a New York Times article. In contrast, a 2014 peer-reviewed medical literature review indicated that ADHD is underdiagnosed in adults.
Studies from multiple countries have reported that children born closer to the start of the school year are more frequently diagnosed with and medicated for ADHD than their older classmates. Boys who were born in December where the school age cut-off was 31 December were shown to be 30% more likely to be diagnosed and 41% more likely to be treated than those born in January. Girls born in December had a diagnosis and treatment percentage increase of 70% and 77% respectively compared to those born in January. Children who were born at the last three days of a calendar year were reported to have significantly higher levels of diagnosis and treatment for ADHD than children born at the first three days of a calendar year. The studies suggest that ADHD diagnosis is prone to subjective analysis.
Rates of diagnosis and treatment have increased in both the United Kingdom and the United States since the 1970s. Prior to 1970, it was rare for children to be diagnosed with ADHD, while in the 1970s rates were about 1%. This is believed to be primarily due to changes in how the condition is diagnosed and how readily people are willing to treat it with medications rather than a true change in incidence. With widely differing rates of diagnosis across countries, states within countries, races, and ethnicities, some suspect factors other than symptoms of ADHD are playing a role in diagnosis, such as cultural norms.
Despite showing a higher frequency of symptoms associated with ADHD, non-White children in the US are less likely than White American children to be diagnosed or treated for ADHD, a finding that is often explained by bias among health professionals, as well as parents who may be reluctant to acknowledge that their child has ADHD. Crosscultural differences in diagnosis of ADHD can also be attributed to the long-lasting effects of harmful, racially targeted medical practices. Medical pseudosciences, particularly those that targeted Black populations during the period of slavery in the US, lead to a distrust of medical practices within certain communities. The combination of ADHD symptoms often being regarded as misbehaviour rather than as a psychiatric condition, and the use of drugs to regulate ADHD, result in a hesitancy to trust a diagnosis of ADHD. Cases of misdiagnosis in ADHD can also occur due to stereotyping of people of color. Due to ADHD's subjectively determined symptoms, medical professionals may diagnose individuals based on stereotyped behaviour or misdiagnose due to cultural differences in symptom presentation.
A 2024 study in CDC's Morbidity and Mortality Weekly Report reports around 15.5 million U.S. adults have attention-deficit hyperactivity disorder, with many facing challenges in accessing treatment. One-third of diagnosed individuals had received a prescription for a stimulant drug in the past year but nearly three-quarters of them reported difficulties filling the prescription due to medication shortages.
The terminology used to describe the condition has changed over time and has included: minimal brain dysfunction in the DSM-I (1952), hyperkinetic reaction of childhood in the DSM-II (1968), and attention-deficit disorder with or without hyperactivity in the DSM-III (1980). In 1987, the symptoms of inattention, impulsivity, and hyperactivity were collectively combined to define the new diagnosis of ADHD, and in 1994 the DSM-IV in split the diagnosis into three subtypes: ADHD inattentive type, ADHD hyperactive-impulsive type, and ADHD combined type.
ADHD, its diagnosis, and its treatment have been controversial since the 1970s. For example, positions differ on whether ADHD is within the normal range of behaviour, and to degree to which ADHD is a genetic condition. Other areas of controversy include the use of stimulant medications in children, the method of diagnosis, and the possibility of overdiagnosis. In 2009, the National Institute for Health and Care Excellence states that the current treatments and methods of diagnosis are based on the dominant view of the academic literature.
Once neuroimaging studies were possible, studies in the 1990s provided support for the pre-existing theory that neurological differences (particularly in the ) were involved in ADHD. A genetic component was identified and ADHD was acknowledged to be a persistent, long-term disorder which lasted from childhood into adulthood. ADHD was split into the current three sub-types because of a field trial completed by Lahey and colleagues and published in 1994. In 2021, global teams of scientists curated the International Consensus Statement compiling evidence-based findings about the disorder.
In 1934, Benzedrine became the first amphetamine medication approved for use in the United States. Methylphenidate was introduced in the 1950s, and enantiopure dextroamphetamine in the 1970s. The use of stimulants to treat ADHD was first described in 1937. Charles Bradley gave the children with behavioural disorders Benzedrine and found it improved academic performance and behaviour.
A 2020 review found that creativity may be associated with ADHD symptoms, particularly divergent thinking and quantity of creative achievements, but not with the disorder of ADHD itself – i.e. it has not been found to be increased in people diagnosed with the disorder, only in people with subclinical symptoms or those that possess traits associated with the disorder. Divergent thinking is the ability to produce creative solutions which differ significantly from each other and consider the issue from multiple perspectives. Those with ADHD symptoms could be advantaged in this form of creativity as they tend to have diffuse attention, allowing rapid switching between aspects of the task under consideration; flexible associative memory, allowing them to remember and use more distantly related ideas which is associated with creativity; and impulsivity, allowing them to consider ideas which others may not have.
Signs and symptoms
Presentations
+Symptoms
!Presentations
!width=45% and symptoms
!width=45% symptoms Inattention Six or more of the following symptoms in children, and five or more in adults, excluding situations where these symptoms are better explained by another psychiatric or medical condition:
Multiple symptoms of inattention that directly negatively impact occupational, academic or social functioning. Symptoms may not be present when engaged in highly stimulating tasks with frequent rewards. Symptoms are generally from the following clusters:
Hyperactivity-Impulsivity Six or more of the following symptoms in children, and five or more in adults, excluding situations where these symptoms are better explained by another psychiatric or medical condition:
Multiple symptoms of hyperactivity/impulsivity that directly negatively impact occupational, academic or social functioning. Typically, these tend to be most apparent in environments with structure or which require self-control. Symptoms are generally from the following clusters:
Combined Meet the criteria for both inattentive and hyperactive-impulsive ADHD. Criteria are met for both inattentive and hyperactive-impulsive ADHD, with neither clearly predominating.
Characteristics in childhood
Emotional dysregulation
Relationship difficulties
Hyperfocus
IQ test performance
Causes
Genetics
Environment
Pathophysiology
Brain structure
Neurotransmitter pathways
Executive function and motivation
Paradoxical reaction to neuroactive substances
Diagnosis
Classification
Diagnostic and Statistical Manual
International Classification of Diseases
Social construct theory
Adults
Differential diagnosis
+ Symptoms related to other disorders
in manic state
in depressive state
Comorbidities
Psychiatric comorbidities
Trauma
Non-psychiatric
Problematic digital media use
Suicide risk
Rejection sensitive dysphoria
Management
Behavioural therapies
Digital interventions
Medication
Stimulants
Non-stimulants
Guidelines
Exercise
Diet
Prognosis
Epidemiology
History
Research directions
Possible positive traits
Possible biomarkers for diagnosis
See also
Further reading
External links
target="_blank" rel="nofollow"> NIMH Pages About Attention-Deficit/Hyperactivity Disorder (ADHD). National Institutes of Health (NIH), U.S. Department of Health and Human Services.
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