| Disorders usually first diagnosed in infancy, childhood, or adolescence. |
Attention-Deficit/Hyperactivity Disorder--
Attention-Deficit/Hyperactivity Disorder (ADHD) previously known as Attention Deficit Disorder
(ADD), is generally considered to be a developmental disorder, largely neurological in nature,
affecting about 5% of the world's population.[1][2][3][4] The disorder 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.[5][6]ADHD is currently
considered to be a persistent and chronic condition for which no medical cure is available. 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 disorder as adults.[7] Studies show
that there is a familial transmission of the disorder which does not occur through adoptive
relationships.[8] Twin studies indicate that the disorder is highly heritable and that genetics
contribute about three quarters of the total ADHD population.
While the majority of ADHD is believed to be genetic in nature,[8] roughly about 1/5 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.[8] 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. Over 200 controlled studies have shown that stimulant
medication is an effective way to treat the symptoms of ADHD.[8][9] Methods of treatment usually
involve some combination of medication, behaviour modification, life style changes, and counseling.
Certain social critics are highly skeptical that the diagnosis denotes a genuine impairment and
question virtually all that is known about ADHD. The symptoms of ADHD are not as profoundly
different from normal behavior as are those of other chronic mental disorders. Still, ADHD has been
shown to often impair functioning, and many adverse life outcomes are associated with ADHD.
Classification
ADHD is a developmental disorder that is often said to be neurological in nature. The term
"developmental" means that certain traits such as impulse control significantly lag in development
when compared to the general population. This developmental lag has been estimated to range
between 30-40 percent in ADHD sufferers 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 neurobehavioural or neurodevelopmental disorders. These compounded
terms are now more frequently used in the field to describe the disorder.[citation needed] The
behavioral classification for ADHD is not completely accurate in that those with Predominately
Inattentive ADHD often display few or no overt behaviors.
Diagnosis
Based on DSM-IV criteria, three types of ADHD are identified:
* 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.
ICD
In the tenth edition of the International Statistical Classification of Diseases and Related Health
Problems (ICD-10) the symptoms of ADHD are given the name "Hyperkinetic disorders". When a
conduct disorder (as defined by ICD-10,[10]) is present, the condition is referred to as "Hyperkinetic
conduct disorder". Otherwise the disorder is classified as "Disturbance of Activity and Attention",
"Other Hyperkinetic Disorders" or "Hyperkinetic Disorders, Unspecified". The latter is sometimes
referred to as, "Hyperkinetic Syndrome".[10]
The American Academy of Pediatrics Clinical Practice Guideline for children with ADHD emphasizes
that a reliable diagnosis is dependent upon the fulfillment of three criteria:[11]
* The use of explicit criteria for the diagnosis using the DSM-IV-TR.
* The importance of obtaining information about the child’s symptoms in more than one setting.
* The search for coexisting conditions that may make the diagnosis more difficult or complicate
treatment planning.
The first criteria can be satisfied by using an ADHD-specific instrument such as the Conners' Rating
Scale.[12] The second criteria is best fulfilled by examining the individual's history. This history can
be obtained from parents and teachers, or a patient's memory.[13] The requirement that symptoms
be present in more than one setting is very important because the problem may not be with the
child, but instead with teachers or parents who are too demanding. The use of intelligence testing,
psychological testing, and neuropsychological testing (to satisfy the third criteria) is essential in
order to find or rule out other factors that might be causing or complicating the problems
experienced by the patient.[14]
The Centers for Disease Control and Prevention (CDC) state that a diagnosis of ADHD should only
be made by trained health care providers, as many of the symptoms may also be part of other
conditions, such as bodily illness or other physiological disorders, such as hyperthyroidism. It is not
uncommon that physically and mentally nonpathological individuals exhibit at least some of the
symptoms from time to time. Severity and pervasiveness of the symptoms leading to prominent
functional impairment across different settings (school, work, social relationships) are major factors
in a positive diagnosis.
Adults often continue to be impaired by ADHD. Adults with ADHD are diagnosed under the same
criteria, including the stipulation that their symptoms must have been present prior to the age of
seven.[15] Adults face some of their greatest challenges in the areas of self-control and self-
motivation, as well as executive functioning, usually having more symptoms of inattention and fewer
of hyperactivity or impulsiveness than children do.[16]
Common comorbid conditions are Oppositional Defiance Disorder (ODD). About 20% to 25% of
children with ADHD meet criteria for a learning disorder.[17] Learning disorders are more common
when there are inattention symptoms.[18]
Causes
PET scans of glucose metabolism in the brains of a normal adult (left) compared to an adult
diagnosed with ADHD (right).
PET scans of glucose metabolism in the brains of a normal adult (left) compared to an adult
diagnosed with ADHD (right).[19]
The exact cause of ADHD remains unknown and in all probability ADHD is a heterogeneous disorder,
meaning that several causes could create very similar symptomology. Still, there is a wide body of
evidence which indicates that the overriding cause of ADHD is genetics. Research suggests that a
large majority of ADHD arises from a combination of various genes, many of which affect dopamine
transporters.[20]
Suspect genes include the 10-repeat allele of the DAT1 gene,[21] the 7-repeat allele of the DRD4
gene,[21] and the dopamine beta hydroxylase gene (DBH TaqI).[22]
Additionally, SPECT scans found people with ADHD to have reduced blood circulation,[23] and a
significantly higher concentration of dopamine transporters in the striatum which is in charge of
planning ahead.[24][25]
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.[citation needed] 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.[26]
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 right 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.[19]
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.[27] 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.
The estimated contribution of non genetic factors to the contribution of all cases of ADHD is 20
percent.[28] 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).[29] 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.[30] This could be related to the fact than 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,[31] possibly because of damage
done to the patient's frontal lobes. Because these types of symptoms can be attributable to brain
damage, the earliest designation for ADHD was "Minimal Brain Damage".[32]
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.[33] 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."[34] Furthermore,
Complex Post Traumatic Stress Disorder can result in attention problems that can look like ADHD, as
can Sensory Integration Disorders.
Despite the lack of evidence that nutrition causes ADHD, studies have found that malnutrition is
correlated with attention deficits.[35]
Treatment
There are several clinically proven effective options available to treat people diagnosed with ADHD.
ADHD is treated most effectively, and cost efficiently, with medication.[36] Psychotherapy is another
option, with or without medication[37] Omega-3 fatty acids, zinc, and magnesium may have benefits
with regards to ADHD symptoms.[38][39]
Comorbid disorders or substance abuse can make finding the proper diagnosis and the right overall
treatment more costly and time-consuming.[40]
Prognosis
ADHD is a developmental disorder meaning that certain traits will be delayed in the ADHD individual.
These traits will develop but just at a much slower rate than the average person. With ADHD it has
been estimated that this lag could be as high as thirty to forty percent in the development of
impulse control. Symptoms of ADHD are often seen by the time a child enters preschool. Those with
ADHD typically have a greater degree of parent-child conflict and emotional reactivity. The incident of
speech problems, central auditory processing difficulties, and coordination problems are all higher
than that of the general population. A marked decrease in academic skills such as reading, spelling,
or math is common with children who have 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 behaviour is seen in 40-70 percent of children at this age. Even ADHD kids
with average to above average intelligence show "chronic and severe underachievement". Fully 46%
of those with ADHD have been suspended and 11% expelled.[citation needed] Thirty seven percent
of those with ADHD do not get a high school diploma even though many of them will receive special
education services.[8] The combined outcomes of the expulsion and dropout rates indicate that
almost half of all ADHD students never finish highschool.[41] Only five percent of those with ADHD
will get a college degree compared to twenty seven percent of the general population. (US Census,
2003)
Social impairment for those with ADHD are seen at both school and work. They often have more
troubled relationships with peers or family members. At the workplace they change jobs more often
and are more likely to get fired. Their income level does not rise as quickly as their peers even when
education level, IQ, and their neighborhood is accounted for. Thirty five percent of all ADHDers will be
self employed in their mid-thirties. Those with ADHD are at greater risk of: injury, abnormal risk
taking, smoking, having learning disabilities, other mental disorders, teen pregnancy, substance
abuse, involvement with the criminal justice system, and having a poorer driving record.[42]
Prevention
There is no known way to prevent ADHD. Some studies indicate an association between mothers
who smoke during pregancy and a higher rate of ADHD in their children. Avoiding smoking, alcohol,
and drugs during pregancy may help prevent a higher risk
of developing ADHD or similar behaviour in offspring.
Epidemiology
ADHD's prevalence worldwide is estimated to be a bit over 5%, with most of the reported variability
being due to methodological characterstics of studies.[4] 10% of males, and (only) 4% of females
have been diagnosed in the U.S.[43] This apparent sex difference may reflect either a difference in
susceptibility or that females with ADHD are less likely to be diagnosed than males.[44][45]
ADHD predominantly inattentive (ADHD-I or ADHD-PI) is one of the four subtypes of Attention-
Deficit Hyperactivity Disorder (ADHD). While ADHD-PI is commonly referred to as Attention Deficit
Disorder (ADD) due to a lack of hyperactivity, but the terms "ADD" and "attention-deficit disorder"
are no longer recognized in the Diagnostic and Statistical Manual of Mental Disorders, fourth edition
(DSM-IV).
Differences from traditional ADHD
ADHD-I is different from the other subtypes of ADHD in that it is characterized by inattention,
daydreaming and lethargy, but with little to none of the hyperactivity, impulsiveness or conduct
disorders typical of the other three ADHD subtypes ("ADHD predominantly hyperactive/impulsive",
"ADHD combined", and "ADHD not otherwise specified."). It is less studied and less understood than
ADHD with hyperactivity because those with ADHD-I are not as disruptive or active as those with
"standard" ADHD and are less likely to be diagnosed.
There has been some debate[citation needed] as to whether all adults who meet the ADHD-I criteria
should in fact receive that diagnosis. It has been noted frequently[citation needed] that hyperactive
children will lose some or all of their hyperactive symptoms as they get older while retaining
inattentive and impulsive symptoms. Some researchers have suggested that these former
hyperactive children should receive the ADHD-combined diagnosis. Hallowell and Ratey (2005)
suggest[1] that the manifestation of hyperactvity simply changes with adolescence and adulthood,
becoming a more generalized restlessness or tendency to fidget.
In the DSM-III, sluggishness, drowsiness, and daydreaming were listed as characteristics of ADHD.
The symptoms were removed from the ADHD criteria in DSM-IV because, although those with ADHD-
I were found to have these symptoms, this only occurred with the absence of hyperactive
symptoms. These distinct symptoms were described as sluggish cognitive tempo (SCT). There is
some debate[citation needed] if those with SCT symptoms may be a homogeneous grouping. It has
been estimated that approximately half of those with ADHD-I can be better described as having SCT
symptoms.
Some experts, such as Dr. Russell Barkley,[2] argue that ADHD-I is so different from "traditional"
ADHD that it should be regarded as a distinct disorder. Barkley cites different symptoms among
those with ADHD-I -- particularly the almost complete lack of conduct disorders and high-risk, thrill-
seeking behavior -- and markedly different responses to stimulant medication.
DSM-IV Criteria
The DSM-IV allows for diagnosis of the predominantly inattentive subtype of ADHD if the individual
presents six or more of the following symptoms of inattention for at least six months to a point that
is disruptive and inappropriate for developmental level:
1. Often does not give close attention to details or makes careless mistakes in schoolwork, work, or
other activities.
2. Often has trouble keeping attention on tasks or play activities.
3. Often does not seem to listen when spoken to directly.
4. Often does not follow instructions and fails to finish schoolwork, chores, or duties in the
workplace (not due to oppositional behavior or failure to understand instructions).
5. Often has trouble organizing activities.
6. Often avoids, dislikes, or doesn't want to do things that take a lot of mental effort for a long
period of time (such as schoolwork or homework).
7. Often loses things needed for tasks and activities (e.g. toys, school assignments, pencils, books,
or tools).
8. Is often easily distracted.
9. Is often forgetful in daily activities.
Importantly for an ADHD-I diagnosis, some of the symptoms that cause impairment must have been
present before seven years of age, and must be present in two or more settings (e.g., at school or
work and at home). There must also be clear evidence of clinically significant impairment in social,
academic, or occupational functioning. Lastly, the symptoms must not occur exclusively during the
course of a pervasive developmental disorder, schizophrenia, or other psychotic disorder, and are
not better accounted for by another mental disorder (e.g., mood disorder, anxiety disorder,
dissociative disorder, personality disorder.)
Examples of observed symptoms
* Failing to pay close attention to details or making careless mistakes when doing schoolwork or
other activities
* Trouble keeping attention focused during play or tasks
* Appearing not to listen when spoken to
* Failing to follow instructions or finish tasks
* Avoiding tasks that require a high amount of mental effort and organization, such as school
projects
* Frequently losing items required to facilitate tasks or activities, such as school supplies
* Excessive distractibility
* Forgetfulness
* Procrastination, inability to begin an activity
* Difficulties completing household chores
* References provided upon request.
Attention-Deficit/Hyperactivity Disorder (ADHD) previously known as Attention Deficit Disorder
(ADD), is generally considered to be a developmental disorder, largely neurological in nature,
affecting about 5% of the world's population.[1][2][3][4] The disorder 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.[5][6]ADHD is currently
considered to be a persistent and chronic condition for which no medical cure is available. 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 disorder as adults.[7] Studies show
that there is a familial transmission of the disorder which does not occur through adoptive
relationships.[8] Twin studies indicate that the disorder is highly heritable and that genetics
contribute about three quarters of the total ADHD population.
While the majority of ADHD is believed to be genetic in nature,[8] roughly about 1/5 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.[8] 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. Over 200 controlled studies have shown that stimulant
medication is an effective way to treat the symptoms of ADHD.[8][9] Methods of treatment usually
involve some combination of medication, behaviour modification, life style changes, and counseling.
Certain social critics are highly skeptical that the diagnosis denotes a genuine impairment and
question virtually all that is known about ADHD. The symptoms of ADHD are not as profoundly
different from normal behavior as are those of other chronic mental disorders. Still, ADHD has been
shown to often impair functioning, and many adverse life outcomes are associated with ADHD.
Classification
ADHD is a developmental disorder that is often said to be neurological in nature. The term
"developmental" means that certain traits such as impulse control significantly lag in development
when compared to the general population. This developmental lag has been estimated to range
between 30-40 percent in ADHD sufferers 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 neurobehavioural or neurodevelopmental disorders. These compounded
terms are now more frequently used in the field to describe the disorder.[citation needed] The
behavioral classification for ADHD is not completely accurate in that those with Predominately
Inattentive ADHD often display few or no overt behaviors.
Diagnosis
Based on DSM-IV criteria, three types of ADHD are identified:
* 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.
ICD
In the tenth edition of the International Statistical Classification of Diseases and Related Health
Problems (ICD-10) the symptoms of ADHD are given the name "Hyperkinetic disorders". When a
conduct disorder (as defined by ICD-10,[10]) is present, the condition is referred to as "Hyperkinetic
conduct disorder". Otherwise the disorder is classified as "Disturbance of Activity and Attention",
"Other Hyperkinetic Disorders" or "Hyperkinetic Disorders, Unspecified". The latter is sometimes
referred to as, "Hyperkinetic Syndrome".[10]
The American Academy of Pediatrics Clinical Practice Guideline for children with ADHD emphasizes
that a reliable diagnosis is dependent upon the fulfillment of three criteria:[11]
* The use of explicit criteria for the diagnosis using the DSM-IV-TR.
* The importance of obtaining information about the child’s symptoms in more than one setting.
* The search for coexisting conditions that may make the diagnosis more difficult or complicate
treatment planning.
The first criteria can be satisfied by using an ADHD-specific instrument such as the Conners' Rating
Scale.[12] The second criteria is best fulfilled by examining the individual's history. This history can
be obtained from parents and teachers, or a patient's memory.[13] The requirement that symptoms
be present in more than one setting is very important because the problem may not be with the
child, but instead with teachers or parents who are too demanding. The use of intelligence testing,
psychological testing, and neuropsychological testing (to satisfy the third criteria) is essential in
order to find or rule out other factors that might be causing or complicating the problems
experienced by the patient.[14]
The Centers for Disease Control and Prevention (CDC) state that a diagnosis of ADHD should only
be made by trained health care providers, as many of the symptoms may also be part of other
conditions, such as bodily illness or other physiological disorders, such as hyperthyroidism. It is not
uncommon that physically and mentally nonpathological individuals exhibit at least some of the
symptoms from time to time. Severity and pervasiveness of the symptoms leading to prominent
functional impairment across different settings (school, work, social relationships) are major factors
in a positive diagnosis.
Adults often continue to be impaired by ADHD. Adults with ADHD are diagnosed under the same
criteria, including the stipulation that their symptoms must have been present prior to the age of
seven.[15] Adults face some of their greatest challenges in the areas of self-control and self-
motivation, as well as executive functioning, usually having more symptoms of inattention and fewer
of hyperactivity or impulsiveness than children do.[16]
Common comorbid conditions are Oppositional Defiance Disorder (ODD). About 20% to 25% of
children with ADHD meet criteria for a learning disorder.[17] Learning disorders are more common
when there are inattention symptoms.[18]
Causes
PET scans of glucose metabolism in the brains of a normal adult (left) compared to an adult
diagnosed with ADHD (right).
PET scans of glucose metabolism in the brains of a normal adult (left) compared to an adult
diagnosed with ADHD (right).[19]
The exact cause of ADHD remains unknown and in all probability ADHD is a heterogeneous disorder,
meaning that several causes could create very similar symptomology. Still, there is a wide body of
evidence which indicates that the overriding cause of ADHD is genetics. Research suggests that a
large majority of ADHD arises from a combination of various genes, many of which affect dopamine
transporters.[20]
Suspect genes include the 10-repeat allele of the DAT1 gene,[21] the 7-repeat allele of the DRD4
gene,[21] and the dopamine beta hydroxylase gene (DBH TaqI).[22]
Additionally, SPECT scans found people with ADHD to have reduced blood circulation,[23] and a
significantly higher concentration of dopamine transporters in the striatum which is in charge of
planning ahead.[24][25]
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.[citation needed] 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.[26]
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 right 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.[19]
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.[27] 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.
The estimated contribution of non genetic factors to the contribution of all cases of ADHD is 20
percent.[28] 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).[29] 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.[30] This could be related to the fact than 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,[31] possibly because of damage
done to the patient's frontal lobes. Because these types of symptoms can be attributable to brain
damage, the earliest designation for ADHD was "Minimal Brain Damage".[32]
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.[33] 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."[34] Furthermore,
Complex Post Traumatic Stress Disorder can result in attention problems that can look like ADHD, as
can Sensory Integration Disorders.
Despite the lack of evidence that nutrition causes ADHD, studies have found that malnutrition is
correlated with attention deficits.[35]
Treatment
There are several clinically proven effective options available to treat people diagnosed with ADHD.
ADHD is treated most effectively, and cost efficiently, with medication.[36] Psychotherapy is another
option, with or without medication[37] Omega-3 fatty acids, zinc, and magnesium may have benefits
with regards to ADHD symptoms.[38][39]
Comorbid disorders or substance abuse can make finding the proper diagnosis and the right overall
treatment more costly and time-consuming.[40]
Prognosis
ADHD is a developmental disorder meaning that certain traits will be delayed in the ADHD individual.
These traits will develop but just at a much slower rate than the average person. With ADHD it has
been estimated that this lag could be as high as thirty to forty percent in the development of
impulse control. Symptoms of ADHD are often seen by the time a child enters preschool. Those with
ADHD typically have a greater degree of parent-child conflict and emotional reactivity. The incident of
speech problems, central auditory processing difficulties, and coordination problems are all higher
than that of the general population. A marked decrease in academic skills such as reading, spelling,
or math is common with children who have 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 behaviour is seen in 40-70 percent of children at this age. Even ADHD kids
with average to above average intelligence show "chronic and severe underachievement". Fully 46%
of those with ADHD have been suspended and 11% expelled.[citation needed] Thirty seven percent
of those with ADHD do not get a high school diploma even though many of them will receive special
education services.[8] The combined outcomes of the expulsion and dropout rates indicate that
almost half of all ADHD students never finish highschool.[41] Only five percent of those with ADHD
will get a college degree compared to twenty seven percent of the general population. (US Census,
2003)
Social impairment for those with ADHD are seen at both school and work. They often have more
troubled relationships with peers or family members. At the workplace they change jobs more often
and are more likely to get fired. Their income level does not rise as quickly as their peers even when
education level, IQ, and their neighborhood is accounted for. Thirty five percent of all ADHDers will be
self employed in their mid-thirties. Those with ADHD are at greater risk of: injury, abnormal risk
taking, smoking, having learning disabilities, other mental disorders, teen pregnancy, substance
abuse, involvement with the criminal justice system, and having a poorer driving record.[42]
Prevention
There is no known way to prevent ADHD. Some studies indicate an association between mothers
who smoke during pregancy and a higher rate of ADHD in their children. Avoiding smoking, alcohol,
and drugs during pregancy may help prevent a higher risk
of developing ADHD or similar behaviour in offspring.
Epidemiology
ADHD's prevalence worldwide is estimated to be a bit over 5%, with most of the reported variability
being due to methodological characterstics of studies.[4] 10% of males, and (only) 4% of females
have been diagnosed in the U.S.[43] This apparent sex difference may reflect either a difference in
susceptibility or that females with ADHD are less likely to be diagnosed than males.[44][45]
ADHD predominantly inattentive (ADHD-I or ADHD-PI) is one of the four subtypes of Attention-
Deficit Hyperactivity Disorder (ADHD). While ADHD-PI is commonly referred to as Attention Deficit
Disorder (ADD) due to a lack of hyperactivity, but the terms "ADD" and "attention-deficit disorder"
are no longer recognized in the Diagnostic and Statistical Manual of Mental Disorders, fourth edition
(DSM-IV).
Differences from traditional ADHD
ADHD-I is different from the other subtypes of ADHD in that it is characterized by inattention,
daydreaming and lethargy, but with little to none of the hyperactivity, impulsiveness or conduct
disorders typical of the other three ADHD subtypes ("ADHD predominantly hyperactive/impulsive",
"ADHD combined", and "ADHD not otherwise specified."). It is less studied and less understood than
ADHD with hyperactivity because those with ADHD-I are not as disruptive or active as those with
"standard" ADHD and are less likely to be diagnosed.
There has been some debate[citation needed] as to whether all adults who meet the ADHD-I criteria
should in fact receive that diagnosis. It has been noted frequently[citation needed] that hyperactive
children will lose some or all of their hyperactive symptoms as they get older while retaining
inattentive and impulsive symptoms. Some researchers have suggested that these former
hyperactive children should receive the ADHD-combined diagnosis. Hallowell and Ratey (2005)
suggest[1] that the manifestation of hyperactvity simply changes with adolescence and adulthood,
becoming a more generalized restlessness or tendency to fidget.
In the DSM-III, sluggishness, drowsiness, and daydreaming were listed as characteristics of ADHD.
The symptoms were removed from the ADHD criteria in DSM-IV because, although those with ADHD-
I were found to have these symptoms, this only occurred with the absence of hyperactive
symptoms. These distinct symptoms were described as sluggish cognitive tempo (SCT). There is
some debate[citation needed] if those with SCT symptoms may be a homogeneous grouping. It has
been estimated that approximately half of those with ADHD-I can be better described as having SCT
symptoms.
Some experts, such as Dr. Russell Barkley,[2] argue that ADHD-I is so different from "traditional"
ADHD that it should be regarded as a distinct disorder. Barkley cites different symptoms among
those with ADHD-I -- particularly the almost complete lack of conduct disorders and high-risk, thrill-
seeking behavior -- and markedly different responses to stimulant medication.
DSM-IV Criteria
The DSM-IV allows for diagnosis of the predominantly inattentive subtype of ADHD if the individual
presents six or more of the following symptoms of inattention for at least six months to a point that
is disruptive and inappropriate for developmental level:
1. Often does not give close attention to details or makes careless mistakes in schoolwork, work, or
other activities.
2. Often has trouble keeping attention on tasks or play activities.
3. Often does not seem to listen when spoken to directly.
4. Often does not follow instructions and fails to finish schoolwork, chores, or duties in the
workplace (not due to oppositional behavior or failure to understand instructions).
5. Often has trouble organizing activities.
6. Often avoids, dislikes, or doesn't want to do things that take a lot of mental effort for a long
period of time (such as schoolwork or homework).
7. Often loses things needed for tasks and activities (e.g. toys, school assignments, pencils, books,
or tools).
8. Is often easily distracted.
9. Is often forgetful in daily activities.
Importantly for an ADHD-I diagnosis, some of the symptoms that cause impairment must have been
present before seven years of age, and must be present in two or more settings (e.g., at school or
work and at home). There must also be clear evidence of clinically significant impairment in social,
academic, or occupational functioning. Lastly, the symptoms must not occur exclusively during the
course of a pervasive developmental disorder, schizophrenia, or other psychotic disorder, and are
not better accounted for by another mental disorder (e.g., mood disorder, anxiety disorder,
dissociative disorder, personality disorder.)
Examples of observed symptoms
* Failing to pay close attention to details or making careless mistakes when doing schoolwork or
other activities
* Trouble keeping attention focused during play or tasks
* Appearing not to listen when spoken to
* Failing to follow instructions or finish tasks
* Avoiding tasks that require a high amount of mental effort and organization, such as school
projects
* Frequently losing items required to facilitate tasks or activities, such as school supplies
* Excessive distractibility
* Forgetfulness
* Procrastination, inability to begin an activity
* Difficulties completing household chores
* References provided upon request.
