Attention deficit disorder is one of the most common reasons for referring children to mental health facilities. Generally children are brought in by the parents, who were informed by the school that their child has difficulties. These difficulties may be related to academic performance, behavior, or both.
Research data supports the idea that children with attention deficit disorder often come from families where attention deficit is present in one or both parents. Very recent data indicate that there is significant heritability of this disorder, pointing to significant genetic predisposition. Out of children who have this disorder, seventy percent will have the disorder as teenagers and about forty to sixty percent will still have the disorder as adults. Genetic studies have not isolated a gene which causes ADHD; however, several genes may contribute to the vulnerability for developing this disorder. Twin studies have shown that there is significant heritability of ADHD. It is estimated that heritability is as high as seventy-six percent. In addition parents and siblings of children with ADHD have a diagnostic probability for attention deficit disorder that is four to five times higher than the general population, and boys are more vulnerable than girls.
Based on these data it would appear that ADHD is easily diagnosed, and thus simple to treat, but the question is, what are the criteria for diagnosing ADHD? Current standards are driven by clinical interviews and collateral histories from the parents and teachers. Occasionally objective assessments, such as continuous performance tasks, are used to evaluate whether or not the child is able to sustain attention for extended periods of time, and whether there is a preference for auditory or visual attention. Various factors may play a role in one’s ability to sustain attention for a period of time. These include: motivation, concurrent anxiety, lack of sleep, low blood sugar, medications, and positively collaborative processes within the family.
Clinically, three major symptom groups are evaluated and considered for ADHD; these involve: inattention, hyperactivity, and impulsivity. Each category carries a description of symptoms; for example inattention may involve an inability to finish tasks, forgetfulness, distractibility, and an inability to organize and sustain efforts. Hyperactivity is defined as being fidgety, unable to sit still, being motorically overly active--running, climbing and moving excessively. Impulsivity involves excessive talking, answering without thinking, inability to wait one’s turn, interrupting, and so on. Both the DSM IV and the ICD 10 provide guidelines for the frequency and duration of the symptoms in the above-mentioned diagnostic categories. Both DSM-IV and ICD 10 generally agree on the necessary number of symptoms before the diagnosis of ADHD is given. It should be pointed out that these symptoms are defined and scored by individuals that are not necessarily trained in this process. Therefore reliability and validity of such data may need to be questioned.
Neuroscientists use approaches that focus primarily on the relationship between the presenting symptoms and potential involvement of brain structure and functions. The brain areas involved in ADHD are the dorsal lateral prefrontal cortex, ventral lateral prefrontal cortex, insula, anterior cingulate, and default networks. Functional involvement of brain structures is linked to neurotransmitter systems; generally we agree that the primary difficulty lies in a patient’s inability to properly utilize the neurotransmitter, dopamine and to lesser extent norepinephrine. Dopamine plays a significant role in a variety of behaviors including the modulation of movement, cognition, mood, and attention. In cases of ADHD, where dopamine is primarily involved, clinical medication interventions can increase dopamine’s availability and significantly improve performance on the continuous performance task, decrease hyperactivity and increase behavior management in school.
Although Methylphenidate is considered to be a first-line medication in treating attention deficit disorder hyperactivity both in children and adults, many children do not respond to this medication. The question arises why this is the case. Recent neuroscientific data point to three types of attentional networks, ventral and dorsal and default executive control, there is overlap in the functions of these networks. It appears that deregulation in either one of these may contribute to some aspects of clinically observable ADHD. How these networks become vulnerable and deregulated can be addressed through understanding the potential risk factors that lead to the development of this disorder. There are many identified potential risk factors that contribute to the clinical presentation of ADHD; these include in utero exposure to drugs, low birth weight, premature delivery, endocrine deregulation, and neglect during early developmental stages, exposure to environmental toxins, head trauma, and genetic vulnerability.
In order to define physiological underpinning of ADHD, qEEG studies showed to be useful. There are clearly identifiable electrical activity patterns that are characterized by increased frontal lobe slowing and excessive frontal theta frequencies that correlate with an inability to sustain attention. Based on this information, the FDA recently approved the use of quantitative EEG as an adjunct assessment tool in the diagnosis of ADHD. Recently, from objective quantitative EEG (qEEG) measures of electrical brain activity, new data are emerging that suggest there may be many different electrical activity patterns for defining children with inattention that fits into the category of ADHD. These findings point to the heterogeneity of the ADHD population. The challenge lies in our understanding of which patterns respond to what type of treatment.
What happens to the adolescence when they become adults? In order to answer this question, we need to understand the presentation of adults with attention deficit disorder. Generally, the symptoms that characterize children and teenagers do not define adult populations; however similar behaviors can be defined and observed. In adults the issue of attention and impulsivity are less evident. However, they may manifest as having inability to concentrate, distractibility, inability to finish tasks, and poor planning, this may result in inability to hold on to standard employment. These individuals are often drawn to work that is considered fast paced and stimulating and potentially linked to immediate rewards. They choose jobs that provide constant stimulation and keep them on edge, such as working in the stock market, sales or emergency room. In addition these individuals often engage in various self-destructive behaviors such as substance abuse, gambling, and other immediately rewarding situations. Simply they have difficulties with a delayed rewards. Treatment in adults may be similar to treatment in children in terms of medication choice. Often medications that target dopamine and perhaps norepinephrine are utilized. In addition behavioral/psychological interventions have shown to be effective particularly when combined with medication regimens.
Currently, data supports the idea that in many cases ADHD is a condition that may be present throughout one’s life; when untreated, ADHD has shown to have significant psychiatric comorbidities that include anxiety, depression, substance abuse, and bipolar disorder. In order to effectively treat these individuals, a clearly established diagnosis needs to be made. A multi-dimensional diagnostic evaluation that addresses patients from a bio-psychosocial, spiritual point of view becomes important. Comprehensive early developmental, family systems, neuropsychological function and brain physiology assessments appear necessary. The findings, based on converging data from various approaches, will provide a better understanding of the patient, the way he/she perceives the environment, and how she/he responds to stressors and solves problems under different conditions and how he or she responds to the rewards. When medications are considered, the choice needs to be made based on patient-specific pharmaco-dynamic and kinetic data. In order to further tailor a medication paradigm, an acute medication challenge using qEEG and neuro-behavioral assessments may be considered. Recent data shows the differential effects of methylphenidate and atomoxetine, with methylphenidate decreasing brain noise by increasing signal-to-noise ratio enhancing overall performance and atomoxetine increasing the salience of task-specific signals increasing specific performance. This approach may enhance therapeutic efficacy and avoid clinical trials that may last for days and weeks and lead to significant hardship for parents and the patient as well as adult individuals with presumed ADHD.
Lukasz Konopka PhD
Chief Neuroscientist, Yellowbrick
Arns, M., Conners, C. K., & Kraemer, H. C. (2013). A Decade of EEG Theta/Beta Ratio Research in ADHD A Meta-Analysis. Journal of attention disorders, 17(5), 374-383.
Castellanos, F. X., & Proal, E. (2010). Large-scale brain systems in ADHD: beyond the prefrontal striatal model. Trends in cognitive sciences, 16(1), 17-26.
Camilleri, N., & Makhoul, S. (2013). ADHD: from childhood into adulthood. Malta Medical Journal, 25(1), 2-7.