Efficacy of Stimulant Medication in the Treatment of ADHD

When examining implications of the childhood diagnosis and pharmacological treatment of attention deficit hyperactivity disorder(ADHD) in children, one is presented with an overwhelming amount of conflicting information. While the disorder has been studied at length both in the United States and worldwide, there exists a profound lack of consensus within the psychiatric community as to the diagnosis, treatment, and outcomes of children with symptomatic attention deficit and hyperactivity. It has been shown in recent years that a substantial increase in attention deficit disorder/hyperactivity disorder(ADHD) drug prescriptions was observed with an average yearly increase of 34%. (Zetterqvist, Asherton, Halldner, Langstrom & Larsson, 2013) The defining characteristics and prevalence of hyperactivity disorder vary significantly from study to study.

In 2016, one study referred to ADHD as a neurodevelopmental disorder with a prevalence of 1.4%-3.0%, concurrently reporting that the disorder was more common in boys than girls. (Thapar & Cooper, 2016) Years prior, in 2011, The Journal of the American Academy of Child and Adolescent Psychiatry reported that ADHD onsets in early childhood and affects 6%-9% of juveniles and 5% of adults, alleging that ADHD persists into adolescence in 75% of cases and into adulthood in approximately one half of cases. (Wilens, Martelon, et al., 2011) While the disparity between these two studies appears to reflect a decrease in the diagnosis of ADHD worldwide, in 2016 in the U.S., 8% of children [were] diagnosed with ADHD and 70% of those [were] taking medications. In spite of the prevalence of ADHD diagnosis and pharmacological treatments in the US and elsewhere, little evidence exists on the effects of ADHD treatment on children's outcomes. (Chorniy & Kitashima, 2016) This paper will examine historical research studies of ADHD as well as several relevant studies from the early 2000s in order to more comprehensively understand the cause and significant positive and negative outcomes of stimulant medication for ADHD at various stages in human development.

Cultural and Societal Implications of Research and Diagnosis of ADHD

When approaching the breadth of information related to ADHD diagnosis and research, it is important to consider the cultural context in which all studies exist. Comorbidity and the intersectional nature of childhood behavioral disorders has in many ways lead to conflicting findings in research related to the childhood identification of ADHD. A major implication of recent research suggests that some groups are disproportionately identified as showing symptoms of behavioral and academic disabilities. Disproportionality in special education refers to a condition in which a group has representation in the special education community that is significantly different from their representation in the general population, or a condition in which their representation is significantly dissimilar to that of a comparison group.

Previous investigations of disproportionate representation of students from certain ethnic groups in special education have suggested that disproportionality is the result of bias against the members of overrepresented groups or, conversely, the result of disproportionate exposure to poverty. (Wiley, Brigham, Kauffman & Bogan, 2013) The bias explanation for disproportionate minority representation in ADHD referrals purports that the overrepresentation of minority students stems mostly from the misidentification of culturally diverse students as having disabilities. This seems to suggest that teachers and other school faculty may be misinterpreting cultural differences as symptoms of disability. It is also important that cultural differences be interpreted within the context of historical oppression. It is paramount that the overrepresentation of students of color in ADHD evaluations is examined in a broad social and political context that includes the history of racism and unfair treatment experienced by ethnic minorities in education and in society in general. (Wiley, et al., 2013)

The poverty explanation for disproportionality in childhood identification of disability and mental health proposes that there is a large body of literature that highlights the gap in health between the most wealthy and the poorest families that has been detected universally across most societies. This point of view would indicate that the long history of the institutional oppression of non-white persons(notably in mental health and educational institutions) has maintained disproportionate rates of poverty across cultural groups. This seems to indicate that minority overrepresentation in the childhood diagnosis of ADHD could be the result of socioeconomic status and not bias. Studies have reported that children and adults are at increased risk of a range of poor outcomes due to socioeconomic disadvantage, including childhood and adolescent mental health disorders. (Russell, Ford, Williams & Russel, 2016) Also worth noting is that there exists a marked under-representation of studies on ADHD from low-income and middle-income countries on a worldwide scale. (Thepar & Cooper, 2016)

However, it is not only the cultural history and socioeconomic status of students that could play a role in the overidentification of non-white students with ADHD. Recent studies have shown that the widely-held political beliefs of the geographic location in which a child lives could substantially impact the diagnosis and treatment they receive. In general, states with more conservatively leaning political views showed consistently lower rates of identification for many mental health disorders. State-level conservativism was found to be a strong indicator of emotional disability [under]identification potentially because people with more conservative political beliefs are less likely to attribute personally uncontrollable causes(like disability) to emotional and behavioral problems. This fundamental difference in the definition of what constitutes a disability could make conservative states less likely to consider special education to be an appropriate response. (Wiley, et al., 2013)

Diagnosis and Stimulant Treatment in Infants

When examining the research implications of ADHD diagnosis and treatment outcomes in infant populations, it is important to firstly consider that said research historically has been based largely on retrospective histories given by mothers. Due to this fact, it should be mentioned that mothers' memory of the infancy of their children tends to be colored by the subsequent development of the childas referrals for evaluation and treatment rarely occur during infancy. When a child grows up to be perceived as well-adjusted and age-appropriate, parents tend to recall an uneventful infancy. Conversely, when a child is referred for evaluation due to difficulties in social or academic arenas, parents' recollection of infancy tends to be distorted in the direction of remembering more deviance. (Weiss, 1975) Commonly, parents begin to notice more problematic behaviors when the children have developed the ability to walk. Frequent causes for parental concerns and referrals typically involve a child's rate of movement throughout the home, propensities to be involved in minor accidents in the home, impulsivity, and an observed absence of natural fear. Historically and in the present day, pharmacological treatments are not advised with this age group.

Diagnosis and Stimulant Treatment in Primary School Children

It is during primary schooling that many children are referred for evaluations for hyperactivity disorders. This is also the age group that is most likely to begin receiving pharmacological treatments in addition to counseling supports or cognitive behavioral therapy. Referrals in many cases come not from parents, but from professionals functioning in supporting roles to the child(i.e. teachers, paraprofessionals, school psychologists, school administration). From the early 1970s until today, the stimulant medications prescribed to children have remained fairly consistent. Typically, methylphenidate and dexamfetamine are the first-line pharmacological treatments for ADHD, and the noradrenaline reuptake inhibitor atomoxetine is the second-line treatment. (Weiss, 1975; Thepar & Cooper, 2016) In all cases, the goal of these treatments is to result in increased levels of catecholamine availability(catecholamines include dopamine, epinephrine and norepinephrine). While meta-analyses did show that both methylphenidate and atomoxetine were effective in treating symptoms of ADHD, there were not without side-effects.

The most common side effects of methylphenidate in primary school aged children were shown to be growth restriction, sleep disturbances, and headaches. Symptoms that occurred less severely or less frequently with methylphenidate treatments included loss of appetite, gastrointestinal symptoms, increase in blood pressure and heart rate, cough, nasopharyngitis, tics, irritability and mood swings, and drowsiness. Atomoxetine showed all of the symptoms prevalent in methylphenidate treatments, but showed an increased likelihood of patients experiencing drowsiness. It should also be mentioned that ADHD shows high concurrent morbidity with other neurodevelopmental disorders during early childhoodnamely autism spectrum disorder, communication and specific learning or motor disorders. Autism spectrum disorders represent the highest rates of comorbidity and side effects of pharmacological treatments in these individuals are more common than in those with ADHD alone. At this time, atypical antipsychotics are not indicated for treatment of core ADHD symptoms in primary school-aged children. (Thepar & Cooper, 2016)

Diagnosis and Stimulant Treatment in Adolescence

While diagnosed significantly less frequently in adolescence than in early childhood, ADHD and the efficacy of it's pharmacological treatment are most frequently assessed in adolescence. While an estimated 70% of U.S. children diagnosed with ADHD are prescribed stimulant medications as part of their treatment, little evidence exists on the effects of ADHD treatment on children's outcomes. Additionally, many studies have produced contradictory results. One 2014 study found that taking stimulant medication is associated with a deterioration in academic outcomes and relationship with parents while a separate study conducted in the same year found that stimulant treatment for ADHD is associated with fewer hospital visits and a reduction in the number of interactions with the police. (Chorniy & Kitashima, 2016) While seemingly contradictory at first glance, it is plausible that these positive and negative outcomes of ADHD treatment are both accurate and that choosing a stimulant treatment for ADHD could in effect prioritize desired outcomes over others less valued by those consenting to treatment.

It has also been evidenced that high rates of substance-use disorders(SUD) have been found in samples of adolescents and adults with attention-deficit/hyperactivity disorder, although conclusive evidence linking the increase specifically to childhood stimulant treatment remains to be empirically gathered. (Wilens et al., 2011) Perhaps most notably in the adolescent population, ADHD stimulant treatments have been shown to reduce the probability and severity of a wide range of short-term and lifetime negative health outcomes, even effectively reducing the probability of an ADHD teenager contracting an STD, becoming pregnant, suffering from a substance use or abuse disorder, and having an injury. (Chorniy & Kitashima, 2016) This evidence would appear to suggest that broadly speaking, ADHD stimulant medications have shown to be effective not only in decreasing the prevalence of risky behavior during adolescence, but decreasing the severity of these behaviors, as well. Additionally, this data would appear to suggest that while a high comorbidity of ADHD and substance abuse disorders continues to be evidenced, adolescent and childhood stimulant treatments could effectively decrease the likelihood of this trend in late-adolescence and adulthood.

Stimulant Treatment Outcomes in Adulthood

While a majority of ADHD diagnosis occur in childhood and early adolescence, many adults continue to experience symptoms of the disorder in adulthood. In early studies of ADHD treatment and in modern trials, researchers have frequently found that many persons with ADHD diagnosis are able to adapt very well to adulthood with or without continuing stimulant treatment. One study as early as 1975 purported that previously hyperactive young adults have adjusted surprisingly well once they have left those environmental circumstances with which they could not cope(for most this included secondary school and for some it included rejecting homes. A greater sense of freedom in adulthood may be compatible with self-management of symptoms of ADHD, as young adult life offers a wider range of life-styles, including varieties of continuing education. (Weiss, 1975) The ability of young adults and adults to exercise more control over their environment may contribute to a trend of stimulant cessation in the 15-21 year age-range. Modern studies related to stimulant cessation report that despite the persistent nature of ADHD symptoms and the demonstrated effect of current ADHD medications, treatment discontinuation is relatively common. As children grow into more autonomous lifestyles, they may be more able to alter their work and home environments to meet their needs effectively. Stimulant cessation in the treatment of ADHD is most common in the 15-21 year age range, with only 27% of individuals in this range still in treatment after 3 years and 11 months, with a median [treatment] duration [of] 1.63 years for the group. (Zetterqvist et al., 2013)

Possible Negative Outcomes of Stimulant Medication

Throughout the history of its use, there have been persistent concerns of long-term effects of stimulant ADHD medication on the development of substance abuse. Heightened concern about a positive correlation between ADHD stimulant treatment and substance use and abuse disorders may stem from the way stimulant medications are interpreted by the human brain. Typically prescribed drugs for ADHD treatment(methylphenidate, dexamfetamine and atomoxetine) increase dopamine concentration in the nucleus accumbuns(a brain region implicated in substance abuse and the proposed neural mechanism for ADHD treatment. ADHD medications largely impact dopamine levels in patients in the same way(and in the same area of the brain) that illicit substances manipulate dopamine levels in the brain of an addict. It goes to follow that children for whom stimulant medications are a part of daily life from a young age may be training their brains to engage in a give and take relationship with an outside substance to maintain levels of dopamine in their system. It is also well documented that there have been reports of abuse and misuse of stimulant ADHD medication[s] themselves. (Chang et al., 2016) While few conclusive studies have specifically addressed stimulant medications potential effect on the development of substance abuse disorders, it has been shown that children with ADHD are more likely to develop disorders of abuse/dependence for nicotine, alcohol, marijuana, cocaine, and other substances.

This high comorbidity could be interpreted as a high risk of dependence or misuse of prescribed ADHD stimulant medications. Children with ADHD are shown to be much more likely to develop substance abuse disorders than children without ADHD and this increased risk is robust to demographic and methodological differences that varied across [multiple] studies. When administering ADHD stimulant medications, it is important to consider the possibility of dependence and the plan for the likely stimulant cessation that occurs for most people between the ages of 15 and 21. (Lee, Humphreys, Flory, Liu & Glass, 2011) The high comorbidity of other disorders concurrently observed with ADHD presents other mental health concerns when determining the safety of stimulant treatments for ADHD. Depression occurs in youths with ADHD at a significantly higher rate than in youths without ADHD. This fact is well documented and calls into question factors that could be leading to concurrent ADHD and depression. It is difficult to say which of these conditions likely occurs first, however ADHD is frequently diagnosed first, suggesting the possibility that early diagnosis and treatment of ADHD may have an effect on the risk of developing subsequent depression. It should also be noted that while most research on the positive or negative relationship of stimulant medication and subsequent depression is inconclusive at best, there is also very little research on the effect of non-stimulant medications, such as atomoxetine.

Documented Positive Outcomes of Stimulant Medication

Throughout the history of stimulant medication use in treatments of ADHD, there have been many documented positive outcomes observed in clinical trials. Many treatments using stimulants have shown that when properly regulated, it is plausible to suggest that ADHD medication has an effect not only on the incidence of negative health outcomes but also on their severity.

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