Adult attention deficit hyperactivity disorder (also referred to as Adult ADHD, Adult ADD) is the common term used to describe the neuropsychiatric condition attention-deficit hyperactivity disorder (ADHD) when it is present in adults. Up to 60% of children diagnosed with ADHD in early childhood continue to demonstrate notable ADHD symptoms as adults.[1] Current convention refers to this condition as adult ADHD, according to the Diagnostic & Statistical Manual for Mental Disorders (DSM-IV-TR), 2000 revision. It has been estimated that 15% of the global population has ADHD (including cases not yet diagnosed).[2]
Successful treatment of ADHD is usually based on a combination of medication, behavior therapy, cognitive therapy, and skills training.[3]
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The DSM-IV, or Diagnostic and Statistical Manual of Mental Disorders, 2000 edition, defines three types of ADHD:
To meet the formal diagnostic criteria of ADHD, an individual must display:
The symptoms (see below) need to have been present since before the individual was seven years old, and must have interfered with at least two spheres of his or her functioning (at home and at school or work, for example) over the last six months.
Individuals with ADHD have deficiencies with self-regulation and self-motivation, that cause problems with distractibility, procrastination, organization, and prioritization. The learning potential and overall intelligence of an adult with ADHD, however, are no different from the potential and intelligence of adults who do not have the disorder. ADHD is a chronic condition, beginning in early childhood and persisting throughout a person's lifetime. It is estimated that up to 60% of children with ADHD will continue to have significant ADHD-related symptoms persisting into adulthood, resulting in a significant impact on education, employment, and interpersonal relationships.[4]
Whereas teachers and caregivers responsible for children are often attuned to the symptoms of ADHD, employers and others who interact with adults are far less likely to regard such behaviors as a symptom. In part, this is because symptoms do change with maturity; adults who have ADHD are less likely to exhibit obvious hyperactive behaviors. Research shows that adults with ADHD are more likely than their non-ADHD counterparts to experience automobile accidents[5] and less likely to complete their education.[6][7] ADHD adults have significantly lower rates of professional employment, even controlling for confounding psychiatric problems.[8]
Adults with ADHD are often perceived by others as chaotic and disorganized, with a tendency to need high stimulation to be less distracted and function effectively. As their coping mechanisms become overwhelmed, some individuals may turn to smoking, alcohol, or illicit drugs. As a result, many adults suffer from associated or "co-morbid" psychiatric conditions such as depression, anxiety, or substance abuse.[4] Many with ADHD also have associated learning disabilities, such as dyslexia, which contributes to their difficulties.[9]
| Inattentive-type (ADHD-I) | Hyperactive/Impulsive-type (ADHD-H) |
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In children:
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In children:
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In adults, these evolve into:[10]
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In adults:
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Most adults with ADHD have the inattentive-type, but men exhibit a tendency towards the hyperactive/impulsive-type symptoms and have predominantly the combined-type. Symptoms of ADHD can vary widely between individuals and throughout the lifetime of an individual. As the neurobiology of ADHD is becoming increasingly understood, it is becoming evident that difficulties exhibited by individuals with ADHD are due to problems with the brain known as executive functioning (see below, neurobiology). These result in problems with sustaining attention, planning, organizing, prioritizing, and impulsive thinking/decision making. These symptoms are independent of an individual's overall intelligence.
The difficulties generated by these symptoms can range from moderate to extreme. Inability to effectively structure their lives, plan simple daily tasks, or think of consequences results in various difficulties: poor performance in school and work leading to academic underachievement or getting fired,[8] poor driving record with traffic violations and accidents,[8] multiple relationships or serial marriages, legal problems, sexually-transmitted diseases, unplanned pregnancies,[11] and smoking, alcoholism, substance abuse.[8] As problems accumulate, a negativistic self-view becomes established and a vicious circle of failure is set up. Up to 80% of adults may have some form of psychiatric comorbidity.[10] The difficulty is often due to the ADHD person's observed behaviour (e.g. the impulsive types, who may insult their boss for instance, resulting in dismissal), despite genuinely trying to avoid these and knowing that it can get them in trouble. Often, the ADHD person will miss things that an adult of similar age and experience should catch onto or know. These lapses can lead others to label the individuals with ADHD as "lazy" or "stupid" or "inconsiderate".
Ultimately, this constellation of symptoms can be summarized as a deficiency in self-regulation and self-motivation, especially for the impulsive/hyperactive types. Assessment of adult patients seeking a possible diagnosis can be better than in children due to the adult's greater ability to provide their own history, input, and insight. However, it has been noted that many individuals, particularly those with high intelligence, develop coping strategies that mask ADHD impairments and therefore they do not present for diagnosis and treatment.[12]
The diagnosis of ADHD in adults is entirely a clinical one, which contributes to controversy. It requires retrospectively establishing whether the symptoms were also present in childhood, even if not previously recognized. There is no objective "test" that diagnoses ADHD. Rather, it is a combination of a careful history of symptoms up to early childhood, including corroborating evidence from family members, previous report cards, etc. along with a neuropsychiatric evaluation. The neuropsychiatric evaluation often includes a battery of tests to assess overall intelligence and general knowledge, self-reported ADHD symptoms, ADHD symptoms reported by others, and tests to screen for co-morbid conditions. Some of these include, but are not limited to the WAIS, BADDS, and/or WURS tests in order to have some objective evidence of ADHD. The screening tests also seek to rule out other conditions or differential diagnoses such as depression, anxiety, or substance abuse. "Organic" diseases such as hyperthyroidism may exhibit symptoms similar to those of ADHD, and it is imperative to rule these out as well. Asperger syndrome, a condition on the autism spectrum, is sometimes mistaken for ADHD, due to impairments in executive functioning found in some people with Asperger syndrome. However, Asperger syndrome also typically involves difficulties in social interaction, restricted and repetitive patterns of behavior and interests, and problems with sensory integration, including hypersensitivity.
Generally, medical and mental health professionals follow the Diagnostic and Statistical Manual of Mental Disorders (DSM) of the American Psychiatric Association. Periodic updates to the DSM incorporate changes in knowledge and treatments.[13] Under the DSM-IV (published in 1994, with corrections and minor changes in 2000), the diagnostic criteria for ADHD in adults follow the same as in children. The proposed revision for the DSM-5 differentiates the presentation of ADHD for children and adults for several symptoms DSM-5 ADHD.
It should be noted that every normal individual exhibits ADHD-like symptoms occasionally (when tired or stressed, for example) but to have the diagnosis, the symptoms should be present from childhood and persistently interfere with functioning in multiple spheres of an individual's life: work, school, and interpersonal relationships. The symptoms that individuals exhibit as children are still present in adulthood, but manifest differently as most adults develop compensatory mechanisms to adapt to their environment.
Over the last 10 years, research into ADHD has greatly accelerated. There is no single, unified theory that explains the cause of ADHD and research is ongoing.
It is becoming increasingly accepted that individuals with ADHD have difficulty with what neuropsychologists term "executive functioning". In higher organisms, such as humans, these functions are thought to reside in the frontal lobes. They enable us to recall tasks that need accomplishing, organize ourselves to accomplish these tasks, assess the consequences of actions, prioritize thoughts and actions, keep track of time, be aware of our interaction with our surroundings, sort out competing stimuli, and adapt to changing situations. They also enable us to judge what is "right" or "correct" as opposed to what is "wrong" or "incorrect".
(Phineas Gage, a railroad worker who in 1848 survived a large iron rod being accidentally driven through his head, is often cited as a demonstration that executive function resides in the frontal lobes, because at least one of those lobes was destroyed in Gage by the accident, after which his behavior and personality were markedly changed. However, while Gage's case certainly stimulated 19th-century thinking about the brain and the localization of its functions, most specific uses of Gage to illustrate theoretical ideas about the brain employ greatly exaggerated descriptions of his behavioral changes.)[14]
The executive functions of the brain in the frontal lobes are thought to be linked to the rest of the brain by way of the prefrontal cortex. This part of the brain is involved in working memory and linked to the limbic system, which controls our basic emotions of fear, anger, pleasure and also plays an important role in the formation of long-term memories. The nucleus accumbens is a part of the brain that is involved in our internal reward system and allows us to feel pleasure, success, or accomplishments in response to certain stimuli. Many of these interconnections are via dopaminergic pathways. For example, cocaine and amphetamines act directly on this part of the brain to stimulate dopamine release, giving users a euphoric feeling.
Several lines of research based on structural and/or functional imaging techniques, stimulant drugs, psychological interventions have identified alterations in the dopaminergic and adrenergic pathways of individuals with ADHD. In particular, areas of the prefrontal cortex appear to be the most affected. Dopamine and norepinephrine are neurotransmitters playing an important role in brain function. The uptake transporters for dopamine and norepinephrine are overly active and clear these neurotransmitters from the synapse a lot faster than in normal individuals. This is thought to increase processing latency, diminishes working memory, and affects salience. To make an analogy, individuals with ADHD have a problem with the search engine of their brain—the "raw" data (knowledge) is all stored in the cortex, but accessing it, prioritizing it, synthesizing it, and keeping it all in mind is problematic.
Stimulants, such as methylphenidate and amphetamine act on these neurons to increase the availability of dopamine and norepinephrine for neurotransmission. They act to correct the problem with the "wiring". Methylphenidate acts by blocking the dopamine and norepinephrine transporters, thus slowing the pace at which these neurotransmitters are cleared from the synapse. Amphetamine acts in a similar fashion, but also increases the release of these neurotransmitters into the synaptic cleft by temporarily reversing the uptake process.
Stimulant medication is a common and effective treatment[15] for Adult ADHD [16][17] although the response rate may be lower for adults than children.[18] The non-stimulant Atomoxetine is also an effective treatment for adult ADHD, without the abuse potential of stimulant medication[19] and has been associated with increased incidence of suicidal thoughts.[20] Some physicians may recommend antidepressant drugs instead of stimulants,[21] though antidepressants have lower treatment effect sizes than stimulant medication.[22]
Treatment for adult ADHD may combine medication and behavioral, cognitive, or vocational interventions. Treatment often begins with medication selected to address the symptoms of ADHD, along with any comorbid conditions that may be present. Medication alone, while effective in correcting the physiological symptoms of ADHD, will not address the paucity of skills which many adults will have failed to acquire because of their ADHD (e.g., one might regain ability to focus with medication, but skills such as organizing, prioritizing and effectively communicating have taken others time to cultivate).
Treatment of adult ADHD may also include forms of anxiety or stress management.
Research has shown that, alongside medication, psychological interventions in adults can be effective in reducing symptomatic deficiencies.[23] Although cognitive behavioral therapy has not proven effective in children with ADHD, it may be helpful in adults.[8]
Stimulant medications are often the first line of treatment and are effective in approximately 80% of individuals.[24] When stimulants are prescribed, low doses are generally recommended for adults with ADHD. High doses of stimulants were generally thought to offer no additional benefit and increase adverse effects,[25] but more recent studies have shown that this may not be true, and in adults with ADHD higher doses (on average 1.1 mg/kg/day) may be most effective.[26] Stimulants are formulated in short-acting, immediate-acting, or long-acting formulations. There is always abuse potential, especially with the short-acting forms which can potentially be injected or insufflated which is why long-acting formulations are recommended. Many of these long-acting formulations prevent them from being injected or insufflated. In adults, stimulants may increase the risk of adverse cardiovascular events such as myocardial infarctions (heart attacks) or hypertension (high blood pressure). Judicious use and careful, regular follow-up with a physician are therefore critically important.
The stimulant methylphenidate (or MPH) is often the first-line therapy. In the short term, methylphenidate is well tolerated however long term safety has not been determined in adults and there are concerns about increases in blood pressure in those treated.[27] Again, careful discussion with the treating physician and good clinical judgment are important to decide on the most appropriate therapy.
Amphetamines and their derivatives are also effective in the treatment of adult ADHD. They not only block the uptake of dopamine and norepinephrine, but increase the release of these from the pre-synaptic neuron. They may have a better side-effect profile than methylphenidate, especially in terms of cardiovascular events, and are potentially better tolerated.[28]
Non-stimulant medication, such as atomoxetine, acts by inhibiting the norepinephrine transporter. It is often prescribed in adults who cannot tolerate the side effects of amphetamines or methylphenidate. It is also effective and approved by the FDA (Food and Drug Administration). A rare but potentially severe side effect includes liver damage and increased suicidal ideation. These should be discussed with the prescribing physician.
Efficacy of neurofeedback in treating attentional deficit in adults has been demonstrated in an outcome study.[29] Research has also shown that neurofeedback outcomes compare favorably to those of stimulant medications.[30]
In North America and Europe, it is estimated that three to five percent of adults have ADHD, but only about ten percent of those have received a formal diagnosis.[31][32] In the context of the World Health Organization World Mental Health Survey Initiative, researchers screened more than 11,000 people aged 18 to 44 years in ten countries in the Americas, Europe and the Middle East. On this basis they estimated the adult ADHD proportion of the population to average 3.5 percent with a range of 1.2 to 7.3 percent, with a significantly lower prevalence in low-income countries (1.9%) compared to high-income countries (4.2%). The researchers concluded that adult ADHD often co-occurs with other disorders, and that it is associated with considerable role disability. Although they found that few adults are treated for ADHD itself, in many instances treatment is given for the co-occurring disorders.[33]
In the 1970s researchers began to realize that the condition now known as ADHD did not always disappear in adolescence, as was once thought. At about the same time, some of the symptoms were also noted in many parents of the children under treatment. The condition was formally recognized as afflicting adults in 1978, often informally called adult ADD, since symptoms associated with hyperactivity are generally less pronounced.
ADHD in adults, as with children, is recognized as an impairment that may constitute a disability under U.S. federal disability nondiscrimination laws, including such laws as the Rehabilitation Act of 1973 and the Americans With Disabilities Act (ADA, 2008 revision), if the disorder substantially limits one or more of an individual's major life activities. For adults whose ADHD does constitute a disability, workplaces have a duty to provide reasonable accommodations, and educational institutions have a duty to provide appropriate academic adjustments or modifications, to help the individual work more efficiently and productively.[34][35]
In a 2004 study it was estimated that the yearly income discrepancy for adults with ADHD was $10,791 less per year than high school graduate counterparts and $4,334 lower for college graduate counterparts. The study estimates a total loss in productivity in the United States of over $77 billion USD. By contrast, loss estimations for drug abuse are $58 billion; for alcohol abuse are $85 billion; and for depression are $43 billion.[36]
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