Attention-Deficit/Hyperactivity Disorder (ADHD)

For an interesting documentary on ADHD in adults, watch the CBC’s Nature of Things: ADHD: Not Just For Kids (Canadian viewers only)

Attention-Deficit/Hyperactivity Disorder (ADHD)

Attention-deficit hyperactivity disorder (ADHD) is the current term for a specific developmental disorder seen in both children and adults that is comprised of deficits in behavioural inhibition, sustained attention and resistance to distraction, and the regulation of one’s activity level to the demands of a situation (hyperactivity or restlessness). This disorder has had numerous different labels over the past century, including hyperactive child syndrome, hyperkinetic reaction of childhood, minimal brain dysfunction, and attention deficit disorder (with or without hyperactivity).

ADHD is one of the most common neurodevelopmental disorders of childhood and adolescence.  According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5: APA, 2013), ADHD is marked by “a persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development…several inattentive or hyperactive-impulsive symptoms were present prior to age 12 years…clear evidence that the symptoms interfere with, or reduce the quality of, social, academic, or occupational functioning.” (APA, 2013, p. 59-60). According to the DSM-5, population surveys across most cultures find the prevalence of ADHD to be approximately 5% in children (and 2.5% in adults).  ADHD is associated with numerous negative outcomes including reduced school performance/academic attainment, poor occupational attainment, social rejection, the development of conduct disorder/antisocial personality disorder, incarceration, substance abuse, physical injuries, traffic accidents/violations, obesity, and negative family relationships (APA, 2013). Thus, early and accurate identification and treatment of ADHD is of enormous societal importance.

How Is ADHD Diagnosed?

The FDA recently approved quantitative EEG (qEEG) for improving that accuracy of ADHD diagnoses (click here and here to learn more). At Niagara Neuropsychology we use qEEG in addition to clinical interviews, behavioural rating scales, and neuropsychological testing to provide the most up-to-date and accurate diagnostic process. There are numerous reasons why a child, adolescent, or adult may have symptoms or behaviours consistent with ADHD. These include sleep disorders, bipolar disorder, depression, anxiety (e.g., Generalized Anxiety Disorder or GAD, Obsessive-Compulsive Disorder or OCD, Posttraumatic Stress Disorder or PTSD), head injuries (e.g., concussions or more significant traumatic brain injuries or TBI), Tourette’s syndrome, thyroid disease, nutritional deficiencies, and learning disorders. When a patient does have ADHD, in addition to the subtypes based on behaviours outlined in the DSM-5, there are also a number of subtypes of ADHD based on qEEG. These include excessive slow wave (e.g., theta) activity in the front part of the brain (the vast majority of ADHD patients fall into this category) or excessive fast wave (beta) activity (a substantial but minority of ADHD patients fall into this category). The effective treatment for these two subtypes is quite different. For example, the use of a stimulant (e.g., Ritalin or Adderall) for those with the high beta subtype may overactivate the brain and lead to worsening of symptoms, including increasing anxiety, appetite suppression, and insomnia. On the other hand, a stimulant is more likely to be effective in those patients with excessive slow wave activity (e.g., theta) in the frontal lobe. Similarly, the neurofeedback training for these two subtypes will be very different.


*Partially adapted from

EEG biofeedback or neurofeedback is a safe and effective treatment of ADHD that improves the core symptoms for patients diagnosed with ADHD. A recent meta-analysis by Arns et al. (2009) of ten well-controlled studies combined with an additional five prospective pre/post design studies.  This meta-analysis concluded that “neurofeedback treatment for ADHD can be considered “Efficacious and specific” (the highest possible ranking) with a large effect size for inattention and impulsivity and a medium effective size for hyperactivity” [p. 180]. In October 2012, the company that maintains the Amer­i­can Academy of Pediatrics’ ranking of research support for psychosocial treatments awarded neurofeedback the highest level of evidence-based support for the treatment of ADHD [PracticeWise, 2012].

For a recent summary of one study that randomly assigned children and adolescents with ADHD to receive either 40 sessions of neurofeedback or computerized brain training, click HERE. Note they found the neurofeedback group had significantly more symptom reduction.

For another example of a randomized controlled trial that compared the effectiveness of neurofeedback to stimulant medication (i.e., methylphenidate or Ritalin), click HERE. This study found that neurofeedback was as effective as stimulant medication. The authors concluded “Neurofeedback was as effective as methylphenidate at treating the attentional and hyperactivity symptoms of ADHD, based on parental reports…This supports the use of neurofeedback as an alternative therapy for children and adolescents with ADHD”.

The International Society for Neurofeedback and Research (ISNR) recently commissioned a comprehensive review of NFB’s evidence-base for the treatment of ADHD.  This review documents that not only has neurofeedback been found to be superior to a variety of experimental control group conditions, but also in three studies neurofeedback was found to be equivalent to stimulant medication in treating the core symptoms of ADHD [Pigott et al., 2013].  Furthermore, the review found five studies that assessed whether or not neurofeedback resulted in sustained benefits after treatment ended, including two studies with two-year follow-up assessments.  In each of these follow-up assessments, the gains from neurofeedback were maintained after treatment had ended and in one study had increased further during the two-year follow-up such that half of the children no longer meet the diagnostic criteria for ADHD.

The MTA Cooperative Study’s follow-up results, the largest ever treatment effectiveness study for ADHD, documented that the commonly reimbursed treatments of stimulant medication and behaviour therapy failed to result in sustained benefit for the vast majority of ADHD children who received them.  This multi-centered NIMH-funded study compared systematic medication management (SMM), multi-component behaviour therapy (BT), combined SMM/BT, and usual community care (CC) groups to evaluate their effectiveness in treating ADHD [Jensen et al., 2007; Molina et al., 2009].   Despite the initial superiority of SMM and combined SMM/BT treatments, these follow-up analyses found that after 2, 6, and 8 years the four treatment groups did not differ on any outcome measure.  Most discouragingly, the researchers report that “the MTA participants fared worse than the local normative comparison group on 91% of the variables tested.” These researchers conclude by stating that “Innovative treatment approaches targeting specific areas of adolescent impairment are needed” [Molina et al., 2009, p. 484].

In contrast to the positive reports of sustained benefit following termination of neurofeedback treatment, stimulant medications’ beneficial effects commonly cease when the medication is stopped, and as found in the MTA study, the authors concluded that there was no evidence to support the “long-term advantage of medication treatment beyond 2 years for the majority of children” [Molina et al., 2009, p.497].  Finally, the just-published follow-up findings from the NIMH-funded Preschool Attention-Deficit/Hyperactivity Disorder Treatment Study (PATS) found results virtually identical to those from the MTA study.  These researchers report that “medication status during follow-up, on versus off, did not predict symptom severity” and despite optimal parent training and systematic medication management at the study’s outset, the authors concluded that “ADHD in preschoolers is a relatively stable diagnosis over a 6-year period. The course is generally chronic, with high symptom severity and impairment, in very young children with moderate-to-severe ADHD, despite treatment with medication. Development of more effective ADHD intervention strategies is needed for this age group” [Riddle et al., 2013, p. 1].

Neurofeedback is one such “innovative” and “more effective” treatment for ADHD with proven effectiveness targeting the specific areas of impairment that are essential to its diagnosis:  1) inattention, 2) impulsivity, and 3) hyperactivity.  Unlike the findings in both the MTA Cooperative and PATS studies, neurofeedback has also been found to result in sustained improvement in ADHD’s core symptoms after the end of treatment.

*The following is partially adapted from Dr. Russell Barkley’s ADHD Factsheet:

MAJOR CHARACTERISTICS: The predominant features of this disorder include:

  • 1. Impaired response inhibition, impulse control, or the capacity to delay gratification. This is often noted in the individual’s inability to stop and think before acting; to wait one’s turn while playing games, conversing with others, or having to wait in line; to interrupt their responding quickly when it becomes evident that their actions are no longer effective; to resist distractions while concentrating or working; to work for larger, longer-term rewards rather than opting for smaller, more immediate ones; and inhibiting the dominant or immediate reaction to an event, as the situation may demand.
  • 2. Excessive task-irrelevant activity or activity that is poorly regulated to the demands of a situation. Individuals with ADHD in many cases are noted to be excessively fidgety, restless, and “on the go.” They display excessive movement not required to complete a task, such as wriggling their feet and legs, tapping things, rocking while seated, or shifting their posture or position while performing relatively boring tasks. Younger children with the disorder may show excessive running, climbing, and other gross motor activity. While this tends to decline with age, even teenagers with ADHD are more restless and fidgety than their peers. In adults with the disorder, this restlessness may be more subjective than outwardly observable, although with some adults they remain outwardly restless as well and report a new to always be busy or doing something and being unable to sit still.
  • 3. Poor sustained attention or persistence of effort to tasks. This problem often arises when the individual is assigned boring, tedious, protracted, or repetitive activities that lack intrinsic appeal to the person. They often fail to show the same level of persistence, “stick-to-it-tiveness,” motivation, and willpower of others their age when uninteresting yet important tasks must be performed. They often report becoming easily bored with such tasks and consequently shift from one uncompleted activity to another without completing these activities. Loss of concentration during tedious, boring, or protracted tasks is commonplace, as is an inability to return to their task on which they were working should they be unexpectedly interrupted. Thus, they are easily distracted during periods when concentration is important to the task at hand. They may also have problems with completing routine assignments without direct supervision, being unable to stay on task during independent work.

These are the three most common areas of difficulty associated with ADHD. However, research is suggesting that those with ADHD, particularly the subtypes associated with impulsive behavior (see below), may also have difficulties in the following areas of psychological functioning as well:

  • 1. Remembering to do things, or working memory. Working memory refers to the capacity to hold information in mind that will be used to guide one’s actions, either now, or at a later time. It is essential for remembering to do things in the near future. Those with ADHD often have difficulties with working memory and so are described as forgetful around doing things, unable to keep important information in mind that they will need to guide their actions later, and disorganized in their thinking and other activities as they often lose track of the goal of their activities. They may often be described as acting without hindsight or forethought, and being less able to anticipate and prepare for future events as well as others, all of which seem to be dependent on working memory. Recently, research suggests that those with ADHD cannot sense or use time as adequately as others in their daily activities, such that they are often late for appointments and deadlines, ill-prepared for upcoming activities, and less able to pursue long-term goals and plans as well as others. Problems with time management and organizing themselves for upcoming events are commonplace in older children and adults with the disorder.
  • 2. Delayed development of internal language (the mind’s voice) and rule-following. Research has lately been suggesting that children with ADHD are significantly delayed in the development of internal language, the private voice inside one’s mind that we employ to converse with ourselves, contemplate events, and direct or command our own behavior. This private speech is absolutely essential to the normal development of contemplation, reflection, and self-regulation. Its delay in those with ADHD contributes to significant problems with their ability to follow through on rules and instructions, to read and follow directions carefully, to follow through on their own plans, rules, and “dolists,” and even to act with legal or moral principles in mind. When combined with their difficulties with working memory, this problem with self-talk or private speech often results in significant interference with reading comprehension, especially of complex, uninteresting, or extended reading assignments.
  • 3. Difficulties with regulation of emotions, motivation, and arousal. Children and adults with ADHD often have problems inhibiting their emotional reactions to events as well as do others of their age. It is not that the emotions they experience are inappropriate, but that those with ADHD are more likely to publicly manifest the emotions they experience than would someone else. They seem less able to “internalize” their feelings, to keep them to themselves, and even to moderate them when they do so as others might do. Consequently, they are likely to appear to others as less emotionally mature, more reactive with their feelings, and more hot-headed, quick-tempered, and easily frustrated by events. Coupled with this problem with emotion regulation is the difficulty they have in generating intrinsic motivation for tasks that have no immediate payoff or appeal to them. This capacity to create private motivation, drive, or determination often makes them appear to lack willpower or self-discipline as they cannot stay with things that do not provide immediate reward, stimulation, or interest to them. Their motivation remains dependent on the immediate environment for how hard and how long they will work, whereas others develop a capacity for intrinsically motivating themselves in the absence of immediate rewards or other consequences. Also related to these difficulties with regulating emotion and motivation is that of regulating their general level of arousal to meet situational demands. Those with ADHD find it difficult to activate or arouse themselves to initiate work that must be done, often complain of being unable to stay alert or even awake in boring situations, and frequently seem to be daydreamy or “in a fog” when they should be more alert, focused, and actively engaged in a task.
  • 4. Diminished problem-solving ability, ingenuity, and flexibility in pursuing long-term goals. Often times, when we are engaged in goal-directed activities, problems are encountered that are obstacles to the goal’s attainment. At these times, individuals must be capable of quickly generating a variety of options to themselves, considering their respective outcomes, and selecting among them those which seem most likely to surmount the obstacle so they can continue toward their goal. Persons with ADHD find such hurdles to their goals to be more difficult to surmount; often giving up their goals in the face of obstacles and not taking the time to think through other options that could help them succeed toward their goal. Thus they may appear as less flexible in approaching problem situations, more likely to respond automatically or on impulse, and so are less creative at overcoming the road-blocks to their goals than others are likely to be. These problems may even be evident in the speech and writing of those with the disorder, as they are less able to quickly assemble their ideas into a more organized, coherent explanation of their thoughts. And so they are less able to rapidly assemble their actions or ideas into a chain of responses that effectively accomplishes the goal given them, be it verbal or behavioral in nature.
  • 5. Greater than normal variability in their task or work performance. It is typical of those with ADHD, especially those subtypes associated with impulsive behavior, to show substantial variability across time in the performance of their work. These wide swings may be found in the quality, quantity, and even speed of their work, failing to maintain a relatively even pattern of productivity and accuracy in their work from moment to moment and day to day. Such variability is often puzzling to others who witness it as it is clear that at some times, the person with ADHD can complete their work quickly and correctly while at others times, their tasks are performed poorly, inaccurately, and quite erratically. Indeed, some researchers see this pattern of high variability in work-related activities to be as much a hallmark of the disorder as is the poor inhibition and inattention described above.

OTHER CHARACTERISTICS: Several other development characteristics are associated with the disorder:

  • 1. Early onset of the major characteristics. The symptoms of ADHD appear to arise, on average, between 3 and 6 years of age. This is particularly so for those subtypes of ADHD associated with hyperactive and impulsive behavior. Others may not develop their symptoms until somewhat later in childhood. But certainly the vast majority of those with the disorder have had some symptoms since before the age of 13 years. Those who have the Predominantly Inattentive Type of ADHD that is not associated with impulsiveness appear to develop their attention problems somewhat later than do the other subtypes, often in middle or later childhood. And so the disorder is believed to be one of childhood onset, regardless of the subtype, suggesting that should these symptoms develop for the first time in adulthood, other mental disorders rather than ADHD should be suspected.
  • 2. Situational variation of symptoms. The major symptoms of ADHD are likely to change markedly as a consequence of the nature of the situation the person happens to be in. Research suggests that those with ADHD behave better in one-to-one situations, when doing tasks that they enjoy or find interesting, when there is some immediate payoff for behaving well, when they are supervised, in their work done earlier in the day rather than later, and, for children, when they are with their fathers compared to their mothers. Conversely, those with ADHD may manifest more of their symptoms in group settings, when they must perform boring work, when they must work independently of supervision, when their work must be done later in the day, and when they are with their mothers. Sometimes or in some cases, these situational factors may have little effect on the person’s level of ADHD symptoms but they have been noted often enough in research to make such situational changes in their symptoms important to appreciate.
  • 3. Relatively chronic course. ADHD symptoms are often quite developmental stable. Although the absolute level of symptoms does decline with age, this is true of the inattentiveness, impulsiveness, and activity levels of normal individuals as well. And so those with ADHD may be improving in their behavior but not always catching up with their peer group in this regard. This seems to leave them chronically behind others of their age in their capacity to inhibit behavior, sustain attention, control distractibility, and regulate their activity level. Research suggests that among those children clinically diagnosed with the disorder in childhood, 50-80 percent will continue to meet the criteria for the diagnosis in adolescence, and 10-65 percent may continue to do so in adulthood. Whether or not they have the full syndrome in adulthood, at least 50-70 percent may continue to manifest some symptoms that are causing them some impairment in their adult life.

ADULT OUTCOME: It has been estimated that anywhere from 15 to 50 percent of those with ADHD ultimately outgrow the disorder. However, these figures come from follow-up studies in which the current and more rigorous diagnostic criteria for the disorder were not used. When more appropriate and modern criteria are employed, probably only 20-35 percent of children with the disorder no longer have any symptoms resulting in impairment in their adult life. Over the course of their lives, a significant minority of those with ADHD experience a greater risk for developing oppositional and defiant behavior (50%+), conduct problems and antisocial difficulties (25-45%), learning disabilities (25-40%), low self-esteem, and depression (25%). Approximately 5-10 percent of those with ADHD may develop more serious mental disorders, such as manic-depression or bipolar disorder. Between 10 and 20 percent may develop antisocial personality disorder by adulthood, most of whom will also have problems with substance abuse. Overall, approximately 10-25 percent develop difficulties with over-use, dependence upon, or even abuse of legal (i.e., alcohol, tobacco) or illegal substances (i.e., marijuana, cocaine, illicit use of prescription drugs, etc.), with this risk being greatest among those who had conduct disorder or delinquency as adolescents. Despite these risks, note should certainly be taken that upwards of half or more of those having ADHD do not develop these associated difficulties or disorders. However, the majority of those with ADHD certainly experienced problems with school performance, with as many as 30-50 percent having been retained in their school grade at least once, and 25-36 percent never completing high school.

As adults, those with ADHD are likely to be under-educated relative to their intellectual ability and family educational background. They are also likely to be experience difficulties with work adjustment, and may be under-employed in their occupations relative to their intelligence, and educational and family backgrounds. They tend to change their jobs more often than others do, sometimes out of boredom or because of interpersonal problems in the workplace. They also tend to have a greater turnover of friendships and dating relationships and seem more prone to marital discord and even divorce. Difficulties with speeding while driving are relatively commonplace, as are more traffic citations for this behavior, and, in some cases, more motor vehicle accidents than others are likely to experience in their driving careers. Thus, they are more likely to have had their driver’s license suspended or revoked.

SUBTYPES: Since 1980, it has become possible to place those with ADHD into several subtypes, depending upon the combinations of symptoms they experience. Those who have difficulties primarily with impulsive and hyperactive behavior and not with attention or concentration are now referred to as having the Predominantly HyperactiveImpulsive Type. Individuals with the opposite pattern, significant inattentiveness without being impulsive or hyperactive are called the Predominantly Inattentive Type. However, most individuals with the disorder will manifest both of these clinical features and so are referred to as the Combined Type of ADHD. Research on those with the Combined Type suggests that they are likely to develop their hyperactive and/or impulsive symptoms first and usually during the preschool years. At this age, then, they may be diagnosed as having the Predominantly HyperactiveImpulsive Type. However, in most of these cases, they will eventually progress to developing the difficulties with attention span, persistence, and distractibility within a few years of entering school such that they will now be diagnosed as having the Combined Type.

There is considerably less research on the Predominantly Inattentive Type of ADHD, or what used to be referred to as attention deficit disorder without hyperactivity. What research does exist suggests some qualitative differences between the attention problems these individuals experience and those with the other types of ADHD in which hyperactive or impulsive behavior is present. The Predominantly Inattentive Type of ADHD appears to be associated with more daydreaming, passiveness, sluggishness, difficulties with focused or selective attention (filtering important from unimportant information), slow processing of information, mental fogginess and confusion, social quietness or apprehensiveness, hypo-activity, and inconsistent retrieval of information from memory. It is also considerably less likely to be associated with impulsiveness (by definition) as well as oppositional/defiant behavior, conduct problems, or delinquency. Should further research continue to demonstrate such differences, there would be good reason to view this subtype as actually a separate and distinct disorder from that of ADHD.

PREVALENCE: ADHD occurs in approximately 3-7 percent of the childhood population and approximately 2-5 percent of the adult population. Among children the gender ratio is approximately 3:1 with boys more likely to have the disorder than girls. Among adults, the gender ratio falls to 2:1 or lower. The disorder has been found to exist in virtually every country in which it has been investigated, including North America, South America, Great Britain, Scandinavia, Europe, Japan, China, Turkey and the middle East. The disorder may not be referred to as ADHD in these countries and may not be treated in the same fashion as in North America but there is little doubt that the disorder is virtually universal among human populations. The disorder is more likely to be found in families in which others have the disorder or where depression is more common. It is also more likely to occur in those with conduct problems and delinquency, tic disorders or Tourette’s Syndrome, learning disabilities, or those with a history of prenatal alcohol or tobacco-smoke exposure, premature delivery or significantly low birth weight, or significant trauma to the frontal regions of the brain.

ETIOLOGIES: ADHD has very strong biological contributions to its occurrence. While precise causes have not yet been identified, there is little question that heredity/genetics makes the largest contribution to the expression of the disorder in the population. The heritability of ADHD averages approximately 80 percent, meaning that genetic factors account for 80 percent of the differences among individuals in this set of behavioral traits. For comparison, consider that this figure rivals that for the role of genetics in human height. Several genes associated with the disorder have been identified and undoubtedly more will be so given that ADHD represents a set of complex behavioral traits and so a single gene is unlikely to account for the disorder. In instances where heredity does not seem to be a factor, difficulties during pregnancy, prenatal exposure to alcohol and tobacco smoke, prematurity of delivery and significantly low birth weight, excessively high body lead levels, as well as post-natal injury to the prefrontal regions of the brain have all been found to contribute to the risk for the disorder in varying degrees. Research has not supported popularly held views that ADHD arises from excessive sugar intake, food additives, excessive viewing of television, or poor child management by parents. Some drugs used to treat seizure disorders in children may increase symptoms of ADHD in those children as side effects of these drugs but these effects are reversible.


Can an EEG Biomarker Aid in the Identification of ADHD? An Examination of the Theta/Beta Ratio (TBR) (by Dr. Chris Friesen, Ph.D., C.Psych., BCN)

Attention Deficit-Hyperactivity Disorder (ADHD) is one of the most common neurodevelopmental disorders of childhood and adolescence.  According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5: APA, 2013), ADHD is marked by “a persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development…several inattentive or hyperactive-impulsive symptoms were present prior to age 12 years…clear evidence that the symptoms interfere with, or reduce the quality of, social, academic, or occupational functioning.” (APA, 2013, p. 59-60). According to the DSM-5, population surveys across most cultures find the prevalence of ADHD to be approximately 5% in children (and 2.5% in adults).  ADHD is associated with numerous negative outcomes including reduced school performance/academic attainment, poor occupational attainment, social rejection, the development of conduct disorder/antisocial personality disorder, incarceration, substance abuse, physical injuries, traffic accidents/violations, obesity, and negative family relationships (APA, 2013). Thus, early and accurate identification and treatment of ADHD is of enormous societal importance.

At this point in time, the standard method of diagnosing ADHD is based solely on a clinical interview by a physician (e.g., pediatrician or psychiatrist) or psychologist.  However, there are numerous problems with the use of clinical interviews for decision making regarding patient diagnoses, predictions, and treatment planning (e.g., various heuristics such as the availability, base-rate, and representativeness heuristics; see Dawes, Faust, & Meehl, 1989) that are beyond the current paper to discuss in detail. The addition of standardized and normative-based behavior/symptom rating scales generally add useful information above and beyond what can be obtained from clinical interview alone. Although such measures are often used, they are not required to make a diagnosis of ADHD according to the DSM-5. However, these measures suffer some of the same flaws of clinical interviews in that they primarily rely on parent, teacher, and/or self-reported symptoms/behaviors. These methods can be problematic due to various biases of the person making the ratings. These can include lack of knowledge of base-rate behaviors, lack of insight, and impression management by those doing the ratings. They can also include teachers’ negative perceptions towards children who misbehave and/or parents’/teachers’ lack of knowledge of normative behaviors at particular ages. For example Elder (2010) found that approximately 8.4% of children who are diagnosed with ADHD are born in the month prior to their cutoff date for kindergarten eligibility (and are thus the youngest and most developmentally immature children within a grade). This is compared to 5.1% of children being diagnosed with ADHD when they are born in the month immediately afterward. This finding is consistent with the possibility that diagnoses/ratings may be being driven by teachers’ lack of knowledge of normative behaviors at particular ages and their perceptions of poor behavior among the youngest children in a classroom. Elder (2010) also found that the youngest children in fifth and eighth grades are nearly twice as likely as their older classmates to regularly use stimulants prescribed to treat ADHD. Thus, even ADHD rating scales that are standardized and normative–based are problematic when it comes to assessing for ADHD. The next level of assessment is the use of neuropsychological/cognitive testing to aid in the identification of ADHD. Although abnormal findings that are consistent with ADHD (e.g., impaired findings on continuous performance tests, inhibition tests such as the Stroop task, working memory, and other executive functioning measures) can be found, many children and adolescents with ADHD display no abnormalities on neuropsychological testing (see Nigg, 2006).  In my own practice, it was not until relatively recently that I relied on a combination of the above measures (i.e., clinical interviews, rating scales, and neuropsychological testing) when I assessed for the presence of ADHD. Although this assessment battery is much more thorough than what a typical pediatrician or psychiatrist does, there is room for improvement.

As noted in the DSM-5, many of the symptoms and behaviors used to diagnose ADHD can be the result of factors other than ADHD including other psychiatric/psychological disorders/symptoms (e.g., anxiety, oppositional behavior, depression, bipolar disorder, disruptive mood dysregulation disorder, substance abuse, autism spectrum disorder, intermittent explosive disorder), medical/neurological conditions (e.g., Tourette’s disorder), or medications taken for other problems (e.g., thyroid medication, bronchodilators). Because of the above (and other) issues, ADHD tends to be over-diagnosed. For example, Bruchmüller, Margraf, and Schneider (2012) found that 16.7% of mental health professionals misdiagnosed ADHD when provided with case vignettes of children that would not meet DSM-IV diagnostic criteria for ADHD but instead met criteria for other diagnoses such an anxiety disorder. Similarly Chilakamarri and Filkowski (2011) found that in children/adolescents with major depressive disorder, 38% were misdiagnosed with ADHD. Similarly, these authors noted that 29% of children/adolescents with bipolar disorder were misdiagnosed with ADHD. Thus, there is evidence that with the standard methods currently being used to diagnose ADHD, many clinicians are not able to accurately do so.

Given that ADHD is considered to be a neurodevelopmental disorder and the various problems with properly assessing and diagnosing ADHD noted above, finding a reliable biomarker for this disorder is likely possible and of critical importance. Although there is research into various biomarkers for ADHD (e.g., the use of fMRI, PET/SPECT scans, blood tests, genetic testing etc.), many of these are of little clinical utility for various reasons (e.g., non-specificity, expensive equipment).  The development of a valid biomarker could not only help properly diagnose children and adolescents, but also help determine the type of, or even whether, pharmacological and/or psychological treatments would be effective.

As noted by Monastra et al. (1999), most major ADHD theorists and researchers have found evidence of anatomical and biochemical abnormalities in the prefrontal cortex in those with ADHD. For example, older imaging studies have found evidence of hypoperfusion and low metabolic activity in the prefrontal and caudate nuclei regions (Monastra et al., 1999). One of the most promising potential biomarkers for aiding in the accurate identification of ADHD is the measurement of the theta/beta ratio (TBR) by use of quantitative electroencephalographs (qEEG). The TBR is essentially the ratio of slow-brain wave activity (theta) to fast-brain wave activity (beta). Higher ratios suggest cortical slowing (i.e., too much slow wave relative to fast wave brain activity). EEG equipment is relatively inexpensive to purchase and run (especially relative to other imaging modalities such as fMRI, PET, and SPECT). For this reason, if EEG indexes such as the TBR can be shown to reliably and accurate aid in the diagnosis of ADHD, it could become relatively easily implemented in hospitals, community clinics, and in private practices of specialist physicians (e.g., neurologists, psychiatrist, and pediatricians) and psychologists.

Although previous researchers have used EEG to look for abnormalities in the brains of those diagnosed with ADHD, it was the work of Joel Lubar (1991) with his use of more extensive EEG recording montages with simplified ratios that found abnormalities. More specifically, Lubar (1991) found increased frontal TBR in boys with attention problems without hyperactivity. It was Lubar and his colleagues (Monastra et al., 1999) who completed a pioneering initial validation study to determine whether the TBR could reliably identify children, adolescents, and young adults of both sexes with or without ADHD. In this study, the authors recruited 482 individuals, ages 6 to 30 years-old, to test the hypothesis that cortical slowing (as measured by via single-channel EEG at the vertex of the scalp) in the prefrontal region could serve as a basis for differentiating patients with ADHD from a nonclinical control group. The authors classified the participants into inattentive-ADHD, inattentive-hyperactive-impulsive combined ADHD, and control (i.e., those not meeting for any DSM-IV disorder and no evidence of ADHD via self-report, ratings scales, and on a continuous performance test) groups. Monastra et al. (1999) found that the TBR measurement revealed evidence of cortical slowing in both ADHD groups, regardless of age or sex. Amazingly, the sensitivity (i.e., the proportion of ADHD patients correctly classified as having ADHD) of the TBR was 86% while the specificity (i.e., the proportion of those without ADHD that were correctly classified as not having ADHD) was 98%.

Monastra et al.’s (1999) results were so promising that Monastra, Lubar, and Linden (2001) completed a series of studies using the qEEG-based TBR in the assessment of ADHD in 469 children and adolescents. They again found that the TBR could correctly classify inattentive-ADHD, inattentive-hyperactive-impulsive combined ADHD, and control participants with a high degree of accuracy. Of course, no measure can be valid without first being demonstrated to be reliable. One important question was whether the TBR readings were consistent over time (i.e., test-retest reliability). The authors found that the TBR was highly reliable (r = .96) when measured one week apart, suggesting that this is likely a stable characteristic of children and adolescents with ADHD. They also found that the TBR findings were consistent with results of rating scales and a continuous performance test (Test of Variables of Attention; TOVA). Lastly, the TBR was found to be able to differentiate those with ADHD and those without ADHD with a sensitivity of 90% and specificity of 94% in their sample.

Since these pioneering studies were performed, many similar studies have been carried out. As will be seen below, despite positive findings, there are some researchers who have found inconsistent results or criticized the use of the TBR. For example Kitsune et al (2015) found that qEEG results varied as a function of the time/context in which they were obtained (i.e., at the beginning or the end of the evaluation). They found that at the start of the recording session, slow wave activity (i.e., delta and theta power) was elevated in their ADHD group only, while at the end of the recording session the ADHD group only demonstrated elevated fast wave activity (higher beta power) relative to controls. However, they did find that the ADHD participants had more slow-wave activity supporting theories of cortical hypoarousal in ADHD. However, Kitsune et al. (2015) did not find evidence for atypical TBR in their sample (n = 76) of adolescents and young adults with ADHD.

Similarly, Buyck and Wiersema (2014) found no evidence of an elevated TBR in their recent study. They concluded that “the findings indicate that it is unlikely that stable, univariate EEG abnormalities are implicated in all children with ADHD and that it is important to take into account state-dependent characteristics when evaluating EEG in ADHD. From a clinical perspective, this implies that cautiousness is warranted in using simple EEG measures as a supplementary diagnostic tool, as has been proposed by some researchers (Monastra, Lubar, & Linden, 2001; Snyder et al., 2008).” (Buyck & Wiersema, 2014, p. 3223). However, these authors only included 22 children with ADHD and 29 typically developing children between 7 and 14 years of age and thus the generalizability of their findings is questionable. Similarly, 50% (11) of the ADHD sample children were taking stimulant medication (although they were asked to abstain for 48 hours before the study). The authors concede that previous research had found that stimulant medication decreases slow wave theta and the TBR.

Once an area of study has matured enough, the gold-standard method of identifying the robustness of a finding is the use of meta-analyses.       Snyder and Hall (2006) completed a meta-analysis examining qEEG studies that evaluated ADHD using DSM-IV criteria. Nine studies (n =1498) met their criteria and they found that the TBR had with a pooled effect size of 3.08 (95% confidence interval, 2.90, 3.26) for ADHD versus controls (normal children, adolescents, and adults). Snyder and Hall (2006) noted that on average, the studies included had sensitivity and specificity rates of 94% which was similar to the results of previous studies. They also noted that their literature search uncovered 32 studies that were carried out before the DSM-IV ADHD criteria were available and that 29 of the 32 studies had findings consistent with their meta-analytic results. They concluded that their meta-analysis supported the finding that higher TBR are commonly found ADHD relative to normal controls. However, they cautioned that high TBR may possibly occur in other conditions and that further research would be required to be sure that a high TBR is specific to ADHD.

Arns, Conners, and Kraemer (2013) conducted a meta-analysis examining the accuracy of the TBR in correctly identifying ADHD. These authors did use a few of the studies used in the previous meta-analysis by Snyder and Hall (2006) if they met their inclusion criteria. Arns et al. (2013) included nine studies (n = 1253) using children/adolescents. They found effect sizes (ES) of 0.75 and 0.62 for 6-13 year-olds and 6-18 year-olds respectively with regard to the magnitude of differences in TBR relative to controls. Due to certain statistical assumptions not being met, they noted that the effect sizes may have been overestimated. These authors concluded that “excessive TBR cannot be considered a reliable diagnostic measure of ADHD, however a substantial sub-group of ADHD patients do deviate on this measure and TBR has prognostic value in this sub-group, warranting its use as a prognostic measure rather than a diagnostic measure.” (Arns et al., 2013, p. 374). They added that “…based on recent studies, this excess theta and TBR is found in a substantial subgroup of patients with ADHD (25%-40%) and has been demonstrated to be of prognostic value in predicting treatment outcome to stimulant medication and neurofeedback, warranting its use as a prognostic measure rather than a diagnostic measure.” (Arns et al., 2013, p. 381). The authors note that their less reliable findings were mainly related to the control groups TBRs increasing as the date of the studies became more recent as opposed to the ADHD group’s TBR decreasing. However, an examination of their graphed data (figure 3 in their published article) of this trend showed a variable trend towards increasing TBR in control subjects primarily due to two or three of the most recent of the included nine studies. They note that this was not due to changes in inclusion criteria for the control groups. Rather they hypothesize that the findings may have been due to differences in the EEG hardware and/or software used and the well-established finding that children are obtaining less sleep each year. In fact, this latter effect (i.e., poor sleep increasing the TBR) is well known in the neurofeedback community (based on my experiencing attending neurofeedback/EEG conferences and workshops). Arns et al. (2013) note that “a recent meta-analysis incorporating data from 35,936 healthy children reported that sleep duration is clearly positively associated with school performance and executive function, and negatively associated with internalizing and externalizing behavior problems.” (p. 380). They also noted that “A well-known EEG signature for fatigue or drowsiness is increased theta suggesting this would result in increased TBR.” (Arns et al., 2013, p. 380). Thus, as sleep duration was not controlled for, the perceived trend of the control groups’ TBRs increasing may have been an artifact of sleep deprivation and thus calls into question the findings of Arns et al. (2013).

To help answer the question of whether the TBR is specific to ADHD, Snyder, Quintana, Sexson, Knott, Haque, and Reynold (2008) conducted a blinded, prospective, multi-center study of a representative clinical sample examining the sensitivity and specificity of the TBR in accurately identifying ADHD relative to as non-ADHD children/adolescents (which included other childhood/adolescent disorders or no diagnosis). Snyder et al.’s (2008) ADHD sample had a number of comorbidities including mood, anxiety, disruptive, and learning disorders. Snyder et al. (2008) found that the TBR identified ADHD with 87% sensitivity and 94% specificity. In comparison, parent and teacher rating scales (the results of which were not available to the clinical team making the diagnosis) were found to have sensitivity ratings of 38% to 79% and specificity ratings of 13% to 61%. The rating scales were often not consistent with the clinical team’s diagnoses whereas the TBR findings were consistent with the team’s diagnoses. The authors cautioned that because TBR findings do not identify comorbidities or alternative diagnoses, the TBR should not be used as a stand-alone diagnostic tool. Rather, they recommended it be used to complement a thorough clinical evaluation. However, in a recent literature review of the clinical utility of EEG in the assessment and treatment of ADHD, Loo and Makeig (2012) examined Snyder et al.’s (2008) study and noted that although the findings suggest that an abnormally high TBR identifies almost all of the children with ADHD, 18% of those with a normal TBR also go on to receive an ADHD diagnosis and state that “for clinical purposes, a misdiagnosis rate of 18% is simply too high.” (Loo & Makeig, 2012, p. 575). However, the Snyder et al. (2008) found a specificity of 94% which suggests that only 6% of those without ADHD are misclassified (false-positive) as having ADHD by having a high TBR. Similarly, their findings found a sensitivity of 87% which suggests that 13% of patients diagnosed with ADHD by the assessment team had normal TBRs (false-negative). And of course, these ratings are assuming that a “team consensus” diagnosis is correct. Loo and Makeig (2012) concede that “the increases in both theta band activity and in the theta/beta power ratio are two of the most reliable EEG findings in ADHD to date.” (p. 572). They also note that Snyder et al.’s (2008) “…results are remarkably consistent with previous reported results using the ?/? power ratio, and suggest that this measure exhibits similar accuracy rates among diverse clinical samples and age ranges. However, an increased ?/? power ratio, as previously reviewed, is not ubiquitous in ADHD…” (p. 575).  They add that “it is difficult to reconcile such disparate results regarding the reliability of the ?/? ratio marker. The Snyder et al. study in 2008 was scientifically sound and it provides class 1 evidence that EEG may indeed be useful in confirming a diagnosis of ADHD as part of a multimodal assessment that includes clinical interviews, behavior rating scales, and neuropsychological tests for identification of comorbid learning disabilities and co-occurring psychiatric disorders. The inconsistencies across studies may be due to methodological issues, such as sampling, instrumentation, and data processing and analysis differences or actual EEG heterogeneity within the ADHD population. In addition, a rarely mentioned fact is that there may be wide variation in EEG instrumentation that can make it extremely difficult to compare across datasets collected with different EEG hardware and software.” (Loo & Makeig, 2008, p. 575).

Bink, Van Boxtel, Popma, Bongers, Denissen, and van Nieuwenhuizen (2015) examined the EEG patterns of adolescents with diagnoses of ADHD only and adolescents with combined autism spectrum disorder (ASD) and ADHD. The authors found that the adolescents with ADHD had more slow (theta) brain-wave activity than adolescents with ASD and ADHD during the eyes open and task conditions. They also found that only the adolescents with ADHD showed a relationship between lowered attention test performance (as measured by the d2) and increased slow-wave activity (theta) in the eyes open condition. The authors interpreted the results as suggesting that the underlying psychophysiological mechanisms of ADHD and ASD-ADHD comorbid adolescents are different, despite there being similarities on a behavioral level as the ASD-ADHD comorbid adolescents demonstrated fewer EEG signs usually associated with ADHD.

A recent meta-analysis by Rudo-Hull (2015) found evidence in support of the cortical hypoarousal theory for externalizing behaviors/disorders in general (which includes ADHD, antisocial personality disorder, conduct disorder, substance abuse, oppositional defiant disorder, and psychopathy). Rudo-Hull (2015) combined the results of 62 studies (n = 4649) that examined qEEG in relationship to externalizing disorders/behaviors. Generally, the author found that for those diagnosed with an externalizing disorder, there was significantly more slow-wave brain activity (i.e., delta but primarily theta) and less fast-wave brain activity (i.e., beta) relative to controls. Rudo-Hull (2015) found that there was no relationship between slow-wave brain activity (i.e., delta and theta) and externalizing behaviors in antisocial or mixed samples. There was a positive relationship between slow-wave brain activity and externalizing behaviors in the ADHD samples however. She also found a negative relationship between fast wave activity (i.e., beta) and externalizing behaviors in both antisocial and ADHD samples. These results led the author to conclude that “…overall, while increased slow-wave activity appears to be more characteristic of ADHD samples, both antisocial and ADHD samples seem to display the decreased fast-wave activity” (Rudo-Hull, 2015, p. 13-14). However, the author noted that the antisocial groups were much more varied (e.g., from children with conduct problems to accused murderers) and there were fewer studies of slow-wave activity in the antisocial samples than in ADHD samples and thus the lack of finding of increased slow wave activity in the antisocial groups may have been due to lack of statistical power. The author added that the TBR, although widely researched within the ADHD field, has not “…been tested in the antisocial behavior field.” (p. 14). The author concluded that “it is therefore possible that these measures (e.g., TBR) may differentiate ADHD from antisocial populations, and future research with these measures may help clarify whether ADHD should continue to be studied largely on its own or in conjunction with other externalizing behaviors.” (p. 14).  Thus, the results from the Snyder et al. (2008), Bink et al. (2015), and Rudo-Hull (2015) studies suggests that the TBR ratio may be relatively specific to ADHD but more research is required.

In one of the best designed studies examining how the TBR will likely be used in a clinical setting (i.e., not as a standalone measure but rather in combination with a clinical assessment) was published by Snyder, Rugino, Hornig, and Stein (2015). The authors investigated the predictive accuracy of adding the TBR to a clinician’s typical assessment procedures via a prospective, triple-blinded, multi-site (13 sites), clinical cohort study (275 children and adolescents presenting to clinics with attentional and behavioral problems) with a diagnosis reference standard based on an independent multidisciplinary team (psychiatrist, psychologist, and neurodevelopmental pediatrician). The authors chose to integrate the clinical assessment with the TBR to help improve certainty with regard to the DSM-5 criterion E (i.e., whether symptoms are better explained by another condition). Similar to what was found in previous studies outlined in the current paper, Snyder et al. (2015) found that the site clinicians likely over-diagnosed ADHD in 34% (93/275) of cases (when compared to the multidisciplinary team’s diagnoses). Of those 34% (93), 91% were found to have lower TBR. The authors also found that when the clinician was uncertain about the diagnosis and was able to integrate their assessment with the TBR, there was 97% agreement with the multidisciplinary team. Generally, Snyder et al. (2015) found that children and adolescents with relatively lower TBR were more likely to have other conditions that could affect criterion E (e.g., anger issues or medical or neurological conditions that mimic ADHD such as brain injuries, headaches, auditory processing disorders, substance abuse, cerebral palsy, vision or hearing problems). They found that integration of TBR with a clinician’s ADHD evaluation could help to improve diagnostic accuracy from 61% to 88%.

In summary, the early and accurate identification and treatment of ADHD is of enormous societal importance due to the numerous possible negative outcomes for those children and adolescents that are undiagnosed and/or undertreated.  Similarly, misdiagnosing children and adolescents with ADHD can also have significant negative psychological consequences (e.g., self-fulfilling prophesies, social ridicule, etc.) in addition to the problems of incorrectly medicating children and adolescents with stimulants that directly affect the brain’s dopamine system at a time when the brain is still developing.  The current paper attempted to demonstrate that the assessment and diagnosis of ADHD has traditionally been problematic. Only a clinical interview is required for diagnosing ADHD as outlined by the DSM-5. There are numerous problems with the use of clinical interviews for decision making regarding patient diagnoses, predictions, and treatment planning. The addition of standardized and normative-based behavior/symptom rating scales generally add useful information above and beyond what can be obtained from clinical interviews alone but can also be problematic. Although the addition of neuropsychological/cognitive testing to aid in the identification of ADHD can be helpful when there are findings of deficits, many children and adolescents with ADHD display no abnormalities on neuropsychological/cognitive testing. Thus, finding a biomarker for the disorder is of critical importance.

Although basic research has repeatedly found evidence of cortical hypoactivation in children and adolescents with ADHD, the methods used were traditionally of little clinical utility for various reasons (e.g., non-specificity, expensive equipment).  However, through the original work of Lubar and Monastra (see Lubar, 1991; Monatra et al., 1999), a relatively cheap and accurate EEG-based measure that can be used to aid in the identification of ADHD appears to have been discovered. This measure is known as the theta-beta ratio (TBR) and is essentially the ratio of slow-brain wave activity (theta) to fast-brain wave activity (beta) with higher ratios suggesting cortical slowing.  The current paper attempted to summarize some of the research with regard to the clinical utility of the TBR in the identification of ADHD. Although not all research has supported the finding of higher TBRs in ADHD children and adolescents relative to controls, the majority of the research has found the TBR to be highly sensitive to ADHD. Although more research should be conducted to insure this finding is robust, the research available to date does suggest that the TBR is also relatively specific to ADHD.

These findings have been convincing enough to cause me to change my clinical practice when it comes to the assessment of ADHD. Although I have always performed relatively comprehensive assessments which have included clinical interviews, rating scales and neuropsychological/cognitive testing, I have very recently added the measurement the TBR via EEG. I do not believe it is wise to use only the TBR when determining the presence or absence of ADHD. All the assessment methods I use are required for a proper differential diagnosis and for treatment planning. Measuring the TBR is especially helpful when trying to confirm an ADHD diagnosis when the other data suggest its presence. For example, if a patient (or patient’s parent/teacher) complains of symptoms and behaviors suggestive of ADHD but there is no indication of an elevated TBR, I will now look at the case much more thoroughly to determine if there is some other explanation for the symptoms other than ADHD. Similarly, I would also make sure the patient has had adequate sleep in the days prior to the assessment due to the fact that poor sleep can potentially affect the TBR. I believe that the incorporation of the TBR in my assessments has allowed me to improve the accuracy of my assessment and hence treatment of ADHD.


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