these regions correlated with the severity of inattention or hyperactivity hemispheric lateralization processes have also been postulated as being implicated in adhd, but empiric results showed contrasting evidence on the topic. neurotransmitter pathways previously, it had been suggested that the elevated number of dopamine transporters in people with adhd was part of the pathophysiology, but it appears the elevated numbers may be due to adaptation following exposure to stimulant medication. current models involve the mesocorticolimbic dopamine pathway and the locus coeruleus-noradrenergic system. adhd psychostimulants possess treatment efficacy because they increase neurotransmitter activity in these systems. there may additionally be abnormalities in serotonergic, glutamatergic, or cholinergic pathways. executive function and motivation the symptoms of adhd arise from a deficiency in certain executive functions (e.g., attentional control, inhibitory control, and working memory). executive functions are a set of cognitive processes that are required to successfully select and monitor behaviours that facilitate the attainment of one's chosen goals. the executive function impairments that occur in adhd individuals result in problems with staying organised, time keeping, excessive procrastination, maintaining concentration, paying attention, ignoring distractions, regulating emotions, and remembering details. people with adhd appear to have unimpaired long-term memory, and deficits in long-term recall appear to be attributed to impairments in working memory. due to the rates of brain maturation and the increasing demands for executive control as a person gets older, adhd impairments may not fully manifest themselves until adolescence or even early adulthood. conversely, brain maturation trajectories, potentially exhibiting diverging longitudinal trends in adhd, may support a later improvement in executive functions after reaching adulthood. 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. paradoxical reaction to neuroactive substances another sign of the structurally altered signal processing in the central nervous system in this group of people is the conspicuously common paradoxical reaction (c. 10–20% of patients). these are unexpected reactions in the opposite direction as with a normal effect, or otherwise significant different reactions. these are reactions to neuroactive substances such as local anesthetic at the dentist, sedative, caffeine, antihistamine, weak neuroleptics and central and peripheral painkillers. since the causes of paradoxical reactions are at least partly genetic, it may be useful in critical situations, for example before operations, to ask whether such abnormalities may also exist in family members. diagnosis adhd is diagnosed by an assessment of a person's behavioural and mental development, including ruling out the effects of drugs, medications, and other medical or psychiatric problems as explanations for the symptoms. adhd diagnosis often takes into account feedback from parents and teachers with most diagnoses begun after a teacher raises concerns. it may be viewed as the extreme end of one or more continuous human traits found in all people. imaging studies of the brain do not give consistent results between individuals; thus, they are only used for research purposes and not a diagnosis. in north america and australia, dsm-5 criteria are used for diagnosis, while european countries usually use the icd-10. the dsm-iv criteria for diagnosis of adhd is 3–4 times more likely to diagnose adhd than is the icd-10 criteria. adhd is alternately classified as neurodevelopmental disorder or a disruptive behaviour disorder along with odd, cd, and antisocial personality disorder. a diagnosis does not imply a neurological disorder. associated conditions that should be screened for include anxiety, depression, odd, cd, and learning and language disorders. other conditions that should be considered are other neurodevelopmental disorders, tics, and sleep apnea. 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. electroencephalography is not accurate enough to make an adhd diagnosis. diagnostic and statistical manual as with many other psychiatric disorders, a formal diagnosis should be made by a qualified professional based on a set number of criteria. in the united states, these criteria are defined by the american psychiatric association in the dsm. based on the dsm-5 criteria published in 2013 and the dsm-5-tr criteria published in 2022, there are three presentations of adhd: adhd, predominantly inattentive type, presents with symptoms including being easily distracted, forgetful, daydreaming, disorganization, poor concentration, and difficulty completing tasks. adhd, predominantly hyperactive-impulsive type, presents with excessive fidgeting and restlessness, hyperactivity, and difficulty waiting and remaining seated. adhd, combined type, is a combination of the first two presentations. 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 social, school or work related problems. 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. international classification of diseases in the eleventh revision of the international statistical classification of diseases and related health problems (icd-11) by the world health organization, the disorder is classified as attention deficit hyperactivity disorder (with the code 6a05). the defined subtypes are similar to those of the dsm-5: predominantly inattentive presentation (6a05.0); predominantly hyperactive-impulsive presentation(6a05.1); combined presentation (6a05.2). however, the icd-11 includes two residual categories for individuals who do not entirely match any of the defined subtypes: other specified presentation (6a05.y) where the clinician includes detail on the individual's presentation; and presentation unspecified (6a05.z) where the clinician does not provide detail. 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. social construct theory the social construct theory of adhd suggests that, because the boundaries between normal and abnormal behaviour are socially constructed (i.e. jointly created and validated by all members of society, and in particular by physicians, parents, teachers, and others), it then follows that subjective valuations and judgements determine which diagnostic criteria are used and thus, the number of people affected. this difference means using dsm-iv criteria could diagnose adhd at rates three to four times higher than icd-10 criteria. thomas szasz, a supporter of this theory, has argued that adhd was "invented and then given a name". adults main article: adult attention deficit hyperactivity disorder adults with adhd are diagnosed under the same criteria, including that their signs must have been present by the age of six to twelve. the individual is the best source for information in diagnosis, however others may provide useful information about the individual's symptoms currently and in childhood; a family history of adhd also adds weight to a diagnosis.: 7, 9 while the core symptoms of adhd are similar in children and adults, they often present differently in adults than in children: for example, excessive physical activity seen in children may present as feelings of restlessness and constant mental activity in adults.: 6 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.: 2 as of 2010, most adults remain untreated. many adults with adhd without diagnosis and treatment have a disorganised life, and some use non-prescribed drugs or alcohol as a coping mechanism. other problems may include relationship and job difficulties, and an increased risk of criminal activities.: 6 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.: 6 adults with adhd may start relationships impulsively, display sensation-seeking behaviour, and be short-tempered.: 6 addictive behaviour such as substance abuse and gambling are common.: 6 this led to those who presented differently as they aged having outgrown the dsm-iv criteria.: 5–6 the dsm-5 criteria does specifically deal with adults unlike that of dsm-iv, which does not fully take into account the differences in impairments seen in adulthood compared to childhood.: 5 for diagnosis in an adult, having symptoms since childhood is required. nevertheless, 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. differential diagnosis symptoms related to other disorders depression disorder anxiety disorder bipolar disorder feelings of hopelessness, low self-esteem or unhappiness loss of interest in hobbies or regular activities fatigue sleep problems difficulty maintaining attention change in appetite irritability or hostility low tolerance for stress thoughts of death unexplained pain persistent feeling of anxiety irritability occasional feelings of panic or fear being hyperalert inability to pay attention tire easily low tolerance for stress difficulty maintaining attention in manic state excessive happiness hyperactivity racing thoughts aggression excessive talking grandiose delusions decreased need for sleep inappropriate social behaviour difficulty maintaining attention in depressive state same symptoms as in depression section the dsm provides potential 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 odd, intermittent explosive disorder, and other neurodevelopmental disorders (such as stereotypic movement disorder and tourette's disorder), in addition to specific learning disorder, intellectual developmental disorder, asd, reactive attachment disorder, anxiety disorders, 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, such as low mood and poor self-image, mood swings, and irritability, can be confused with dysthymia, cyclothymia or bipolar disorder as well as with borderline personality disorder.: 10 some symptoms that are due to anxiety disorders, personality disorder, developmental disabilities or intellectual disability or the effects of substance abuse such as intoxication and withdrawal can overlap with adhd. these disorders can also sometimes occur along with adhd. medical conditions which can cause adhd-type symptoms include: hyperthyroidism, seizure disorder, lead toxicity, hearing deficits, hepatic disease, sleep apnea, drug interactions, untreated celiac disease, and head injury. 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 hyperactivity and inattentiveness. obstructive sleep apnea can also cause adhd-type symptoms. management main article: attention deficit hyperactivity disorder management the management of adhd typically involves counseling or medications, either alone or in combination. while treatment may improve long-term outcomes, it does not get rid of negative outcomes entirely. medications used include stimulants, atomoxetine, alpha-2 adrenergic receptor agonists, and sometimes antidepressants. in those who have trouble focusing on long-term rewards, a large amount of positive reinforcement improves task performance. adhd stimulants also improve persistence and task performance in children with adhd. "recent evidence from observational and registry studies indicates that pharmacological treatment of adhd is associated with increased achievement and decreased absenteeism at school, a reduced risk of trauma-related emergency hospital visits, reduced risks of suicide and attempted suicide, and decreased rates of substance abuse and criminality". behavioural therapies