Attention Deficit Hyperactivity Disorder (ADHD)


Attention Deficit Hyperactivity Disorder, ADHD, is one of the most common mental disorders that develop in children. Children with ADHD have impaired functioning in multiple settings, including home, school, and in relationships with peers. If untreated, the disorder can have long-term adverse effects into adolescence and adulthood.


It is a neurobehavioral developmental disorder affecting about 3-5% of the world’s population under the age of 19. It typically presents itself during childhood, and is characterized by a persistent pattern of inattention and/or hyperactivity, as well as forgetfulness, poor impulse control or impulsivity, and distractibility. ADHD is currently considered to be a persistent and chronic condition for which no medical cure is available, although medication can be prescribed. ADHD is most commonly diagnosed in children and, over the past decade, has been increasingly diagnosed in adults. About 60% of children diagnosed with ADHD retain the condition as adults. It appears to be highly heritable, although one-fifth of all cases are estimated to be caused from trauma or toxic exposure. Methods of treatment usually involve some combination of medications, behavior modifications, life style changes, and counseling.

The scientific consensus in the field, and the consensus of the national health institutes of the world, is that ADHD is a disorder which impairs functioning, and that many adverse life outcomes are associated with ADHD. It has been frequently said by a minority of news sources, social critics, certain religions, and individual medical professionals, to be a controversial disorder. These criticisms fall outside of majority or minority viewpoint and question its causes, its treatment, and even the existence of ADHD.

ADHD is a developmental disorder, in that, in the diagnosed population, certain traits such as impulse control significantly lag in development when compared to the general population. Using magnetic resonance imaging, this developmental lag has been estimated to range between 3 years, to 5 years in the prefrontal cortex of those with ADHD patients in comparison to their peers; consequently these delayed attributes are considered an impairment. ADHD has also been classified as a behavior disorder and a neurological disorder or combinations of these classifications such as neurobehavioral or neurodevelopmental disorders.
Three forms of ADHD are thought to exist, ADHD-PI or ADHD Primarily Inattentive (previously known as ADD or Attention Deficit Disorder), ADHD-PH/I or ADHD Primarily Hyperactive/Impulsive, and ADHD-C or combined type. The majority of studies have looked at ADHD-C, with much less work done on ADHD-PI. To determine or rule out ADHD information from several key sources is required.


The most common symptoms of ADHD are distractibility, difficulty with concentration and focus, short term memory loss, procrastination, problems organizing ideas and belongings, tardiness, impulsivity, and weak planning and execution. Not all people with ADHD have all the symptoms. The Diagnostic and Statistical Manual of Mental Disorders categorises the symptoms of ADHD into two clusters: Inattention symptoms and Hyperactivity/Impulsivity symptoms. Most ordinary people exhibit some of these behaviors but not to the point where they seriously interfere with the person’s work, relationships, or studies or cause anxiety or depression. Children do not often have to deal with deadlines, organization issues, and long term planning so these types of symptoms often become evident only during adolescence or adulthood when life demands become greater.

Symptoms of ADHD will appear over the course of many months, and include:

* Impulsiveness: a child who acts quickly without thinking first
* Hyperactivity: a child who can’t sit still, walks, runs, or climbs around when others are seated, talks when others are talking.
* Inattention: a child who daydreams or seems to be in another world, is sidetracked by what is going on around him or her.

According to a majority of medical research in the United States, as well as other countries, ADHD is today generally regarded as a chronic disorder for which there are some effective treatments, but no true cure. Evidence suggests that hyperactivity has a strong heritable component, and in all probability ADHD is a heterogeneous disorder, meaning that several causes could create very similar symptomology. Candidate genes include dopamine transporter (DAT), dopamine receptor D4 (DRD4), dopamine beta-hydroxylase (DBH), monoamine oxidase A (MAOA), catecholamine-methyl transferase (COMT), serotonin transporter promoter (SLC6A4), 5-hydroxytryptamine 2A receptor (5-HT2A), and 5-hydroxytryptamine 1B receptor (5-HT1B). Researchers believe that a large majority of ADHD arises from a combination of various genes, many of which affect dopamine transporters. Suspect genes include the 10-repeat allele of the DAT1 gene, the 7-repeat allele of the DRD4 gene, and the dopamine beta hydroxylase gene (DBH TaqI).

Genome wide surveys have shown linkage between ADHD and loci on chromosomes 7, 11, 12, 15, 16, and 17. If anything, the broad selection of targets indicates the likelihood that ADHD does not follow the traditional model of a “genetic disease” and is better viewed as a complex interaction among genetic and environmental factors. As the authors of a review of the question have noted, “Although several genome-wide searches have identified chromosomal regions that are predicted to contain genes that contribute to ADHD susceptibility, to date no single gene with a major contribution to ADHD has been identified.”

Studies show that there is a familial transmission of the disorder which does not occur through adoptive relationships.  Twin studies indicate that the disorder is highly heritable and that genetics contribute about three quarters of the total ADHD population.[8] While the majority of ADHD is believed to be genetic in nature,[8] roughly one-fifth of all ADHD cases are thought to be acquired after conception due to brain injury caused by either toxins or physical trauma prenatally or postnatally.

Additionally, SPECT scans found people with ADHD to have reduced blood circulation, and a significantly higher concentration of dopamine transporters in the striatum which is in charge of planning ahead. Medications focused on treating A.D.H.D.(such as methylphenidate) work because they force blood to flow in certain areas of the brain, those that control and regulate concentration, which usually don’t receive a normal or sufficient amount blood flow or circulation in the brains of A.D.H.D. en companying individuals. A study by the U.S. Department of Energy’s Brookhaven National Laboratory in collaboration with Mount Sinai School of Medicine in New York suggest that it is not the dopamine transporter levels that indicate ADHD, but the brain’s ability to produce dopamine itself. The study was done by injecting 20 ADHD subjects and 25 control subjects with a radiotracer that attaches itself to dopamine transporters. The study found that it was not the transporter levels that indicated ADHD, but the dopamine itself. ADHD subjects showed lower levels of dopamine across the board. They speculated that since ADHD subjects had lower levels of dopamine to begin with, the number of transporters in the brain was not the telling factor. In support of this notion, plasma homovanillic acid, an index of dopamine levels, was found to be inversely related not only to childhood ADHD symptoms in adult psychiatric patients, but to “childhood learning problems” in healthy subjects as well.

Although there is evidence for dopamine abnormalities in ADHD, it is not clear whether abnormalities of the dopamine system are the molecular abnormality of ADHD or a secondary consequence of a problem elsewhere. Researchers have described a form of ADHD in which the abnormality appears to be sensory overstimulation resulting from a disorder of ion channels in the peripheral nervous system.

An early PET scan study found that global cerebral glucose metabolism was 8.1% lower in medication-naive adults who had been diagnosed as ADHD while children. The image on the left illustrates glucose metabolism in the brain of a ‘normal’ adult while doing an assigned auditory attention task; the image on the right illustrates the areas of activity in the brain of an adult who had been diagnosed with ADHD as a child when given that same task; these are not pictures of individual brains, which would contain substantial overlap, these are images constructed to illustrate group-level differences. Additionally, the regions with the greatest deficit of activity in the ADHD patients (relative to the controls) included the premotor cortex and the superior prefrontal cortex.[24] A second study in adolescents failed to find statistically significant differences in global glucose metabolism between ADHD patients and controls, but did find statistically significant deficits in 6 specific regions of the brains of the ADHD patients (relative to the controls). Most notably, lower metabolic activity in one specific region of the left anterior frontal lobe was significantly inversely correlated with symptom severity.[25] These findings strongly imply that lowered activity in specific regions of the brain, rather than a broad global deficit, is involved in ADHD symptoms. However, these readings are of subjects doing an assigned task. They could be found in ADHD diagnosed patients because they simply were not attending to the task. Hence the parts of the brain used by others doing the task would not show equal activity in the ADHD patients.[citation needed]

The estimated contribution of non genetic factors to the contribution of all cases of ADHD is 20 percent.[26] The environmental factors implicated are common exposures and include alcohol, in utero tobacco smoke and lead exposure. Lead concentration below the Center for Disease Control’s action level account for slightly more cases of ADHD than tobacco smoke (290 000 versus 270 000, in the USA, ages 4 to 15). Complications during pregnancy and birth—including premature birth—might also play a role. It has been observed that women who smoke while pregnant are more likely to have children with ADHD. This could be related to the fact that nicotine is known to cause hypoxia (lack of oxygen) in utero, but it could also be that ADHD women have more probabilities to smoke both in general and during pregnancy, being more likely to have children with ADHD due to genetic factors.

Head injuries can cause a person to present ADHD-like symptoms, possibly because of damage done to the patient’s frontal lobes. Because these types of symptoms can be attributable to brain damage, one earlier designation for ADHD was “Minimal Brain Damage”.

There is no compelling evidence that social factors alone can create ADHD. Many researchers believe that attachments and relationships with caregivers and other features of a child’s environment have profound effects on attentional and self-regulatory capacities. It is noteworthy that a study of foster children found that an inordinate number of them had symptoms closely resembling ADHD. An editorial in a special edition of Clinical Psychology in 2004 stated that “our impression from spending time with young people, their families and indeed colleagues from other disciplines is that a medical diagnosis and medication is not enough. In our clinical experience, without exception, we are finding that the same conduct typically labelled ADHD is shown by children in the context of violence and abuse, impaired parental attachments and other experiences of emotional trauma.” Furthermore, Complex Post Traumatic Stress Disorder can result in attention problems that can look like ADHD, as can Sensory Integration Disorders.

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It is believed that there are several different causes of ADHD. Roughly 80 percent of ADHD is considered genetic in nature and the estimated contribution of non genetic factors to the contribution of all cases of ADHD is believed to be 20 percent.. Environmental agents also cause ADHD. These agents, such as alcohol, tobacco, and lead, are believed to stress babies prenatally and cause ADHD. Studies have found that malnutrition is also correlated with attention deficits. Diet seems to cause ADHD symptoms or make them worse. Many studies point to synthetic preservatives and artificial coloring agents aggravating ADD & ADHD symptoms in those affected. Older studies were inconclusive quite possibly due to inadequate clinical methods of measuring offending behavior. Parental reports were more accurate indicators of the presence of additives than clinical tests. Several major studies show academic performance increased and disciplinary problems decreased in large non-ADD student populations when artificial ingredients, including artificial colors were eliminated from school food programs.. Professor John Warner stated, “significant changes in children’s hyperactive behaviour could be produced by the removal of artificial colourings and sodium benzoate from their diet.” and “you could halve the number of kids suffering the worst behavioural problems by cutting out additives”.

In 1982, the NIH had determined, based on research available at that time, that roughly 5% of children with ADHD could be helped significantly by removing additives from their diet. The vast majority of these children were believed to have food allergies. More recent studies have shown that approximately 60-70% of children with and without allergies improve when additives are removed from their diet,   that up to almost 90% of them react when an appropriate amount of additive is used as a challenge in double blind tests,and that food additives may elicit hyperactive behavior and/or irritability in normal children as well.

If ADHD is suspected, the diagnosis should be made by a professional with training in ADHD. After ruling out other possible reasons for the child’s behavior, the specialist checks the child’s school and medical records and talks to teachers and parents who have filled out a behavior rating scale for the child. A diagnosis is made only after all this information has been considered.

Many of the symptoms of ADHD occur from time to time in everyone. In those with ADHD the frequency of these symptoms occurs frequently and impairs regular life functioning typically at school or at work. Not only will they perform poorly in task oriented settings but they will also have difficulty with social functioning with their peers. No objective physical test exists to diagnose ADHD in a patient. As with many other psychiatric and medical disorders, the formal diagnosis is made by a qualified professional in the field based on a set number of criteria. In the USA these critera are laid down by the American Psychiatric Association in their Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), 4th edition. Based on the DSM-IV criteria listed below, three types of ADHD are classified:

1. ADHD, Combined Type: if both criteria 1A and 1B are met for the past 6 months
2. ADHD Predominantly Inattentive Type: if criterion 1A is met but criterion 1B is not met for the past six months
3. ADHD, Predominantly Hyperactive-Impulsive Type: if Criterion 1B is met but Criterion 1A is not met for the past six months.

The terminology of ADD expired with the revision of the most current version of the DSM. Consequently, ADHD is the current nomenclature used to describe the disorder as one distinct disorder which can manifest itself as being a primary deficit resulting in hyperactivity/impulsivity (ADHD, predominately hyperactive-impulsive type) or inattention (ADHD predominately inattentive type) or both (ADHD combined type).

Effective treatments for ADHD are available, and include behavioral therapy and medications.
Singularly, stimulant medication is the most efficient and cost effective method of treating ADHD. Over 200 controlled studies have shown that stimulant medication is an effective way to treat ADHD. Methods of treatment usually involve some combination of medications, behaviour modifications, life style changes, and counseling. Behavioral Parent Training, behavior therapy aimed at parents to help them understand ADHD, has also shown short term benefits. Omega-3 fatty acids, phosphatidylserine, zinc and magnesium may have benefits with regard to ADHD symptoms.

Comorbid disorders or substance abuse can make finding the proper diagnosis and the right overall treatment more costly and time-consuming. Psychosocial therapy is useful in treating some comorbid conditions.

ADHD Medications:

Another part of the treatment program often involves the prescribed use of certain medications. Parents sometimes worry about their children having to rely on medication. But it’s more important to realize that these can help the ADHD child function at his best, and will consequently help him avoid even greater problems.

Parents should expect to receive detailed information about any prescribed medication from their health professional, including the possible side-effects. This information should then be shared with everyone entrusted with the child’s care. Let’s now look at the most common of ADHD medication.


The most commonly prescribed ADHD medication is Methylphenidate. This medication is in fact a stimulant, which interestingly in ADHD children often has the reverse effect of calming them down.

Methylphenidate, also known as Ritalin, is commonly taken in pill form. It takes effect quickly, and lasts three to four hours. The child’s prescribed dosage needs to be administered by an informed adult, two or three times a day, depending on the child’s age – usually in the morning before school, and at lunchtime. Methylphenidate is now also available in a single dose, long acting forms. Dextroamphetamine is another medication used to treat ADHD.

Before medication therapy begins, the diagnosis should be well established, and individualized behaviour and educations plans should be in place. In the absence of these other forms of treatment, drug therapy alone is ineffective.

What about “drug holidays”?

In the past, children being treated for ADHD were sometimes given an extended break from taking medication – usually during the summer months when not in school – to minimize potential side effects. But today, most physicians suggest that current ADHD medication therapy can be safely followed year-round, and can continue to be very helpful outside of school as well. The benefits offered by modern ADHD medications as part of a greater treatment plan, usually outweigh the minimized potential for adverse side effects.

What about alternative treatments?

Alternative treatments for the child’s ADHD may be suggested to you, but it’s important to realize there is no significant scientific evidence that any are effective. Some of these controversial treatments include: biofeedback, mega-vitamin and mineral supplements, anti-motion sickness medication, and optometric exercises. Again, none of these approaches have ever been scientifically proven to have any significant effect on ADHD, so they should probably not be relied on.

The need for on-going monitoring

Whatever treatment strategies are undertaken, the child’s condition needs to be regularly monitored by a health professional. It is especially important to check for side-effects; confirm the on-going effectiveness of the program; and if necessary, make adjustments to the treatment plan.

The diagnosis of ADHD implies an impairment in life functioning. Many adverse life outcomes are associated with ADHD.

During the elementary years, an ADHD student will have more difficulties with work completion, productivity, planning, remembering things needed for school, and meeting deadlines. Oppositional and socially aggressive behavior is seen in 40-70% of children at this age. Even ADHD kids with average to above average intelligence show “chronic and severe under achievement”. Fully 46% of those with ADHD have been suspended and 11% expelled. 37% of those with ADHD do not get a high school diploma even though many of them will receive special education services. The combined outcomes of the expulsion and dropout rates indicate that almost half of all ADHD students never finish highschool.Only 5% of those with ADHD will get a college degree compared to 27% of the general population. (US Census, 2003)

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose


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