Some environmental factors contribute to attention deficit hyperactivity disorder (ADHD), such as childhood stroke and brain injuries. However, genetics is the likely cause in most people.
ADHD is one of the most commonTrusted Source mental health conditions doctors diagnose in children. It can be a lifelong condition, though symptoms may present differently in adulthood. Research suggestsTrusted Source people tend to be born with ADHD rather than developing it spontaneously.
This article will discuss which environmental factors could be responsible for ADHD and whether a person can avoid or overcome them.
Attention deficit hyperactivity disorder (ADHD ) is a mental disorder of the neurodevelopmental type. It is characterized by difficulty paying attention, excessive activity, and behavior without regards to consequences which is not appropriate for a person's age. There are also often problems with regulation of emotions. The symptoms appear before a person is twelve years old, are present for more than six months, and cause problems in at least two settings (such as school, home, or recreational activities). In children, problems paying attention may result in poor school performance. Additionally there is an association with other mental disorders and substance misuse. Although it causes impairment, particularly in modern society, many people with ADHD can have sustained attention for tasks they find interesting or rewarding (known as hyperfocus).
Despite being the most commonly studied and diagnosed mental disorder in children and adolescents, the exact cause is unknown in the majority of cases. It affects about of children when diagnosed via the DSM-IV criteria and when diagnosed via the ICD-10 criteria. It is estimated to affect about people globally. Rates are similar between countries and depend mostly on how it is diagnosed. although the disorder is often overlooked in girls because their symptoms differ from those of boys. people diagnosed in childhood continue to have symptoms into adulthood and between of adults have the condition. In adults inner restlessness rather than hyperactivity may occur. They often develop coping skills which make up for some or all of their impairments. The condition can be difficult to tell apart from other conditions, as well as to distinguish from high levels of activity that are still within the range of normative behaviors.
ADHD management recommendations vary by country and usually involve some combination of counseling, lifestyle changes, and medications. The British guideline only recommends medications as a first-line treatment in children who have severe symptoms and for medication to be considered in those with moderate symptoms who either refuse or fail to improve with counseling, though for adults medications are a first-line treatment. Canadian and American guidelines recommend that medications and behavioral therapy be used together as a first-line therapy, except in preschool-aged children. Stimulant medication therapy is not recommended as a first-line therapy in preschool-aged children in either guideline. Treatment with stimulants is effective for at least 14 months; however, their long term effectiveness is unclear and there are potentially serious side effects.
The medical literature has described symptoms similar to those of ADHD since the 18th century. ADHD, its diagnosis, and its treatment have been considered controversial. The controversies have involved clinicians, teachers, policymakers, parents, and the media. Topics include ADHD's causes and the use of stimulant medications in its treatment. Most healthcare providers accept ADHD as a genuine disorder in children and adults, and the debate in the scientific community mainly centers on how it is diagnosed and treated. The condition was officially known as attention-deficit disorder (ADD), while before this it was known as hyperkinetic reaction of childhood.
Signs and symptoms
| ADHD symptoms | |
|---|---|
| Inattention | Hyperactivity-impulsivity |
|
|
Inattention, hyperactivity (restlessness in adults), disruptive behavior, and impulsivity are common in ADHD. Academic difficulties are frequent as are problems with relationships. The symptoms can be difficult to define, as it is hard to draw a line at where normal levels of inattention, hyperactivity, and impulsivity end and significant levels requiring interventions begin.
symptoms must be present for six months or more to a degree that is much greater than others of the same age and they must cause significant problems functioning in at least two settings (e.g., social, school/work, or home). The criteria must have been met prior to age twelve in order to receive a diagnosis of ADHD. This requires more than 5 symptoms of inattention or hyperactivity/impulsivity for those under 17 and more than 4 for those over.
Subtypes
ADHD is divided into three subtypes: predominantly inattentive(ADHD-PI or ADHD-I), predominantly hyperactive-impulsive (ADHD-PH or ADHD-HI)
A person with ADHD inattentive type has most or all of following symptoms, excluding situations where these symptoms are better explained by another psychiatric or medical condition:
- Be easily distracted, miss details, forget things, and frequently switch from one activity to another
- Have difficulty maintaining focus on one task
- Become bored with a task after only a few minutes, unless doing something they find enjoyable
- Have difficulty focusing attention on organizing or completing a task
- Have trouble completing or turning in homework assignments, often losing things (e.g., pencils, toys, assignments) needed to complete tasks or activities
- Appear not to be listening when spoken to
- Daydream, become easily confused, and move slowly
- Have difficulty processing information as quickly and accurately as others
- Struggle to follow instructions
- Have trouble understanding details; overlooks details
A person with ADHD hyperactive-impulsive type has most or all of the following symptoms, excluding situations where these symptoms are better explained by another psychiatric or medical condition:
- Fidget or squirm a great deal
- Talk nonstop
- Dash around, touching or playing with anything and everything in sight
- Have trouble sitting still during dinner, school, and while doing homework
- Be constantly in motion
- Have difficulty performing quiet tasks or activities
- Be impatient
- Blurt out inappropriate comments, show their emotions without restraint, and act without regard for consequences
- Have difficulty waiting for things they want or waiting their turn in games
- Often interrupt conversations or others' activities
Girls with ADHD tend to display fewer hyperactivity and impulsivity symptoms but more symptoms pertaining to inattention and distractability. Symptoms of hyperactivity tend to go away with age and turn into "inner restlessness" in teens and adults with ADHD.
People with ADHD of all ages are more likely to have problems with social skills, such as social interaction and forming and maintaining friendships. This is true for all subtypes. About half of children and adolescents with ADHD experience social rejection by their peers compared to non-ADHD children and adolescents. People with attention deficits are prone to having difficulty processing verbal and nonverbal language which can negatively affect social interaction. They also may drift off during conversations, miss social cues, and have trouble learning social skills.
Difficulties managing anger are more common in children with ADHD as are poor handwriting and delays in speech, language and motor development. Although it causes significant difficulty, many children with ADHD have an attention span equal to or better than that of other children for tasks and subjects they find interesting.
Associated disorders
In children, ADHD occurs with other disorders about two-thirds of the time. Some commonly associated conditions include:
- Epilepsy
- Tourette's syndrome
- Autism spectrum disorder (ASD): this disorder affects social skills, ability to communicate, behaviour, and interests.
- Digital media use
- Anxiety disorders have been found to occur more commonly in the ADHD population.
- Intermittent explosive disorder
- 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.
- Obsessive–compulsive disorder (OCD) can co-occur with ADHD and shares many of its characteristics.
- Intellectual disabilities
- Reactive attachment disorder
- Substance use disorders. Adolescents and adults with ADHD are at increased risk of substance abuse. 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. This makes the evaluation and treatment of ADHD more difficult, with serious substance misuse problems usually treated first due to their greater risks.
- 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 behavioral therapy 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.
- Oppositional defiant disorder (ODD) and conduct disorder (CD), which occur with ADHD in cases respectively. They are characterized by antisocial behaviors such as stubbornness, aggression, frequent temper tantrums, deceitfulness, lying, and stealing. About half of those with hyperactivity and ODD or CD develop antisocial personality disorder in adulthood. Brain imaging supports that conduct disorder and ADHD are separate conditions.
- Primary disorder of vigilance, which is characterized by poor attention and concentration, as well as difficulties staying awake. These children tend to fidget, yawn and stretch and appear to be hyperactive in order to remain alert and active.
- Sluggish cognitive tempo (SCT) is a cluster of symptoms that potentially comprises another attention disorder. It may occurs in ADHD cases, regardless of the subtype.
- Stereotypic movement disorder
- Mood disorders (especially bipolar disorder and major depressive disorder). Boys diagnosed with the combined ADHD subtype are more likely to have a mood disorder. Adults with ADHD sometimes also have bipolar disorder, which requires careful assessment to accurately diagnose and treat both conditions.
- 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.
- People with ADHD have an increased risk of persistent bed wetting.
- A 2016 systematic review found a well established association between ADHD and obesity, asthma and sleep disorders, and tentative evidence for association with celiac disease and migraine, while another 2016 systematic review did not support a clear link between celiac disease and ADHD, and stated that routine screening for celiac disease in people with ADHD is discouraged.
Intelligence
Overall, studies have shown that people with ADHD tend to have lower scores on intelligence quotient (IQ) tests. The significance of this is controversial due to the differences between people with ADHD and the difficulty determining the influence of symptoms, such as distractibility, on lower scores rather than intellectual capacity. In studies of ADHD, higher IQs may be over represented because many studies exclude individuals who have lower IQs despite those with ADHD scoring on average nine points lower on standardized intelligence measures.
Studies of adults suggest that differences in intelligence are not meaningful and may be explained by associated health problems.
Causes
Most ADHD cases are of unknown causes. It is believed to involve interactions between genetics, the environment, and social factors. Certain cases are related to previous infection of or trauma to the brain.
Genetics
Twin studies indicate that the disorder is often inherited from one's parents with genetics determining about 75% of cases. Siblings of children with ADHD are three to four times more likely to develop the disorder than siblings of children without the disorder. Genetic factors are also believed to be involved in determining whether ADHD persists into adulthood.
Typically, a number of genes are involved, many of which directly affect dopamine 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 behavioral phenotypes, including ADHD symptoms reflecting split attention.
Evolution may have played a role in the high rates of ADHD, particularly hyperactive and impulsive traits in males. Some have hypothesized that some women may be more attracted to males who are risk takers, increasing the frequency of genes that predispose to hyperactivity and impulsivity in the gene pool. Others have claimed that these traits may be an adaptation that help males face stressful or dangerous environments with, for example, increased impulsivity and exploratory behavior. In certain situations, ADHD traits may have been beneficial to society as a whole even while being harmful to the individual. The high rates and heterogeneity of ADHD may have increased reproductive fitness and benefited society by adding diversity to the gene pooldespite being detrimental to the individual. In certain environments, some ADHD traits may have offered personal advantages to individuals, such as quicker response to predators or superior hunting skills.
People with Down syndrome are more likely to have ADHD.
Environment
In addition to genetics, some environmental factors might play a role in causing ADHD. Alcohol intake during pregnancy can cause fetal alcohol spectrum disorders which can include ADHD or symptoms like it. Children exposed to certain toxic substances, such as lead or polychlorinated biphenyls, may develop problems which resemble ADHD. Exposure to the organophosphateinsecticides chlorpyrifos and dialkyl phosphate is associated with an increased risk; however, the evidence is not conclusive. Exposure to tobacco smoke during pregnancy can cause problems with central nervous system development and can increase the risk of ADHD.
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). There is an association between long term but not short term use of acetaminophen during pregnancy and ADHD. 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 food dyes or preservatives may be associated with an increased prevalence of ADHD or ADHD-like symptoms, but the evidence is weak and may only apply to children with food sensitivities. They have put in place regulatory measures based on these concerns. In a minority of children, intolerances or allergies to certain foods may worsen ADHD symptoms.
Research does not support popular beliefs that ADHD is caused by eating too much refined sugar, watching too much television, parenting, poverty or family chaos; however, they might worsen ADHD symptoms in certain people.
Society
The youngest children in a class have been found to be more likely to be diagnosed as having ADHD, possibly due to their being developmentally behind their older classmates. This effect has been seen across a number of countries. They also appear to use ADHD medications at nearly twice the rate as their peers.
In some cases, the diagnosis of ADHD may reflect a dysfunctional family or a poor educational system, rather than problems with the individuals themselves. In other cases, it may be explained by increasing academic expectations, with a diagnosis being a method for parents in some countries to get extra financial and educational support for their child. Typical behaviors of ADHD occur more commonly in children who have experienced violence and emotional abuse.
The social construct theory of ADHD suggests that because the boundaries between "normal" and "abnormal" behavior 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 could lead to the situation where the DSM-IV arrives at levels of ADHD three to four times higher than those obtained, a supporter of this theory, has argued that ADHD
Pathophysiology
Current models of ADHD suggest that it is associated with functional impairments in some of the brain's neurotransmitter systems, particularly those involving dopamine and norepinephrine. The dopamine and norepinephrine pathways that originate in the ventral tegmental area and locus coeruleus project to diverse regions of the brain and govern a variety of cognitive processes. The dopamine pathways and norepinephrine pathways which project to the prefrontal cortex and striatum are directly responsible for modulating executive function (cognitive control of behavior), motivation, reward perception, and motor function; these pathways are known to play a central role in the pathophysiology of ADHD. Larger models of ADHD with additional pathways have been proposed.
Brain structure
In children with ADHD, there is a general reduction of volume in certain brain structures, with a proportionally greater decrease in the volume in the left-sided prefrontal cortex. The posterior parietal cortex also shows thinning in ADHD individuals compared to controls. Other brain structures in the prefrontal-striatal-cerebellar and prefrontal-striatal-thalamic circuits have also been found to differ between people with and without ADHD.
The subcortical volumes of the accumbens, amygdala, caudate, hippocampus, and putamen appears smaller in individuals with ADHD compared with controls. Inter-hemispheric asymmetries in white matter tracts have also been noted in ADHD youths, suggesting that disruptions in temporal integration may be related to the behavioral characteristics of ADHD.
Neurotransmitter pathways
Previously it was thought that the elevated number of dopamine transporters in people with ADHD was part of the pathophysiology but it appears that the elevated numbers are due to adaptation to exposure to stimulants. 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 serotoninergic, 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 behaviors that facilitate the attainment of one's chosen goals. The executive function impairments that occur in ADHD individuals result in problems with staying organized, 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. The criteria for an executive function deficit are met of children and adolescents with ADHD. One study found that 80% of individuals with ADHD were impaired in at least one executive function task, compared to 50% for individuals without ADHD. 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.
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 behavior for short-term rewards.
Diagnosis
ADHD is diagnosed by an assessment of a child's behavioral and mental development, including ruling out the effects of drugs, medications and other medical or psychiatric problems as explanations for the symptoms. It 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. Whether someone responds to medications does not confirm or rule out the diagnosis. As imaging studies of the brain do not give consistent results between individuals, they are only used for research purposes and not diagnosis.
. It is classified as neurodevelopmental psychiatric disorder. Additionally, it is classified as a disruptive behavior disorder along with oppositional defiant disorder, conduct disorder, and antisocial personality disorder. A diagnosis does not imply a neurological disorder.
Associated conditions that should be screened for include anxiety, depression, oppositional defiant disorder, conduct disorder, and learning and language disorders. Other conditions that should be considered are other neurodevelopmental disorders, tics, and sleep apnea.
Diagnosis of ADHD using quantitative electroencephalography(QEEG) is an ongoing area of investigation, although the value of QEEG in ADHD is currently unclear. In the United States, the Food and Drug Administration has approved the use of QEEG to evaluate ADHD. The approved test uses the ratio of EEG theta to betaactivity to guide diagnosis; however, at least five studies have failed to replicate the finding.
Self rating are used in the screening and evaluation of ADHD.This ends today's session.Have a good day.
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