Attention Deficit Hyperactivity Disorder, Term Paper Example

Abstract

The paper provides a detailed observation of the incidence and etiology of Attention Deficit Hyperactivity Disorder (ADHD). A literature review of primary research results is performed. The paper evaluates the relevance of the assumption that the growth of ADHD in North America is staggering.

Keywords: Attention Deficit Hyperactivity Disorder, genetic, hereditary, etiology, environment

Final Paper

The growth of Attention Deficit Hyperactivity Disorder in North America is staggering – this assumption has already turned into a belief. Really, that ADHD is the most common form of psychopathology in children is difficult to deny: recent research findings confirm that the rates of ADHD among children with learning difficulties are higher than usual, and many researchers agree that ADHD among children is on the rise. For years, professionals in education and genetics sought to analyze the ADHD etiology and incidence. Yet, numerous difficulties, barriers, and research inconsistencies did not allow making a single, universal, and absolutely reliable conclusion regarding the rates of ADHD in North American children and the factors influencing ADHD risks. The current state of research does not provide sufficient information about the roots of ADHD and its incidence. Although the prevailing majority believes ADHD to be an entirely genetic disorder, years will pass before the public has a better understanding of the roots, mechanisms, and the real incidence of ADHD in children.

Literature Review

Overview

The current state of literature provides vast amount of information about the causes of Attention Deficit Hyperactivity Disorder (ADHD) in children. In their research of the ADHD roots and etiology, researchers usually keep to the definition and diagnostic criteria provided by DSM-IV. The latter treats ADHD as “a complex neurodevelopmental condition characterized by a persistent pattern of inattention and/ or hyperactivity-impulsivity that is more frequent and severe than is typically observed in individuals at a comparable level of development” (Stefanatos & Baron, 2007). ADHD in children manifests through excessive and inappropriate motor activity, the lack of concentration, limit control responses, and impaired ability to switch attention (Stefanatos & Baron, 2007). The symptoms of ADHD tend to develop in childhood but can persist during adolescence and even adulthood (Stefanatos & Baron, 2007). The majority of those diagnosed with ADHD also face various learning problems, problems with social adjustment, and problems with emotional well-being (Stefanatos & Baron, 2007). The presence of co-morbid states and factors makes it difficult to diagnose ADHD on time and to objectively estimate the incidence and prevalence of ADHD across various population groups. Nevertheless, researchers provide some basic information about the state of ADHD in North America.

Incidence of ADHD

According to Stefanatos and Baron (2007), ADHD in the United States annually impacts approximately 4.4 million children aged between 4-17 years. 50 to 80% of those diagnosed with ADHD during early preschool years will have to live and fight with ADHD symptoms and complications all their lives (Stefanatos & Baron, 2007). Many of those displaying the symptoms of ADHD face the risks of various co-morbid factors: for example, Autism Spectrum Disorder can accompany ADHD (Rommelse et al., 2010). Both disorders share the same heritability and are being influenced by the similar developmental factors (Rommelse et al., 2010). In a similar fashion, children diagnosed with ADHD commonly reveal other related complications, including various learning disabilities.

Despite the wealth of literature on the topic, most research findings are at least controversial. More often than not, the results of primary researches are contradictory and do not create conditions necessary to evaluate and explore the etiology and incidence of ADHD in the United States and North America. For example, Davison and Ford (2001) write that the incidence of ADHD in the United States is on the rise; moreover, ADHD is the most common psychopathology in children and the reason of the 600% increase in the use of various stimulant medications, needed to treat this disorder. Glass and Wegar (2000) agree to this view of the situation, stating that ADHD is a commonly publicized condition that affects school-age children, and suggest that approximately 5 percent of children have ADHD. The authors recognize that the specific estimates of ADHD incidence in children vary between 3 and 9 percent, but ADHD is still the most common form of pediatric psychiatric disorders (Glass & Wegar, 2000). Milberger et al (1996) refer to 6-9% estimates, while Albayrak et al (2008) show 3-7% incidence among children and adolescents. An impression persists that modern researchers operate mostly similar statistical results and seek to create a truthful picture of ADHD incidence in children. The situation with the etiology of ADHD is more complex and controversial: researches in the field of psychology and psychopathology provide controversial information. Albayrak et al (2008) says that the etiology and pathogenesis of ADHD are poorly understood – this is, actually, a brief explanation of the current situation in ADHD research. The wealth of primary research findings does not improve the overall situation: the prevailing majority still keeps to a belief that ADHD is the product of solely genetic influences and has nothing to do with environmental factors.

Etiology: The role of genetics

The link between ADHD and genetic factors is the dominant line of modern research on ADHD. Dozens of researchers confirm ADHD to be the product of multiple hereditary factors. Needless to say, the heritability of ADHD is rather high, and dopaminergic neurotransmission systems are primarily responsible for the development and persistence of ADHD symptoms in children (Banaschewski et al, 2010). In this sense, the study by Willcutt, Pennington and DeFries (2000) is of particular value: the authors suggest that individual differences in ADHD are attributable to genetic factors. Moreover, given the existing controversies in literature and research on ADHD, it is important to replicate and extend previous researches, in order to have a better understanding of genetic influences in the context of ADHD, Willcutt, Pennington and DeFries (2000) investigated the etiology of ADHD in a sample of twins, of which at least one had problems with learning and socialization. The authors revealed absolute scores on measures that attribute ADHD to genetic influences and heritability, and concluded that different symptoms of ADHD display different vulnerability and dependence on genetic factors. (Willcut, Pennington & DeFries, 2000).  For example, inattention as one element of ADHD pathogenesis in children was absolutely due to genetic influences and highly heritable; simultaneously, impulsivity and hyperactivity as the two other elements of ADHD in children were not linked to genetic factors (Willcutt, Pennington and DeFries, 2000). As a result, not only should researchers pay attention to the relevance of hereditary factors in ADHD, but must be able to distinguish between primary and secondary genetic influences on various ADHD symptoms.

Wood et al (2010) support the belief that ADHD is a highly heritable health condition and write that 76% of ADHD cases develop as a result of the complex interactions between genetic factors and mechanisms. Wood et al (2000) did not simply investigate the role of hereditary factors in the development of ADHD but tried to link these factors to children’s IQ. They tried to prove that ADHD and IQ are being influenced by one and the same set of genetic factors. It appears, however, that ADHD and IQ are independent categories. The genetic factors that influence IQ and ADHD in children are different, too. Because the study of IQ has been more systematic than that of ADHD, researchers could have a chance to use their IQ research findings in their study of the ADHD etiology. Yet, IQ and ADHD do not share genetic influences, and researchers in ADHD must begin the process of exploring the etiology of the disease from the very beginning: In its current state, the IQ research does not offer a single chance to better understand ADHD development mechanisms in children and adolescents.

Despite these controversies and the difficulties in researching the etiology of ADHD in children, hereditary factors and genetic influences remain the primary factors of the research analysis. Researchers explore various aspects of ADHD development in children and the influence of genetic mechanisms on it. Here, Derks (2007) suggest that the variance in ADHD in boys and girls is attributable to genetic influences; and although both girls and boys are influenced by one and the same system of genes, some elements of the ADHD variance are also attributable to different genes. According to Derks et al (2007), the finding about gender-specific variations in ADHD have far-reaching implications for the analysis of factors that influence and predetermine various behaviors in boys and girls. Shared data and findings cannot fully explain behavioral variability in boys and girls. To understand the etiology of ADHD, genetic influences and gender differences must be taken into account, to produce a more coherent picture of ADHD in North America.

Etiology: Environmental factors

Today, when ADHD is believed to be primarily the product of genetic influences, some researchers still seek to investigate the role of environmental factors in the development of ADHD in children. According to Wood et al (2010), only 76% of ADHD symptoms develop as a result of genetic influences, while the remaining 24% must be the product of children’s interactions with the environment. Actually, Derks et al (2007) support this assumption, saying that some of ADHD variations are attributable to environmental influences. In this context, different researchers choose to investigate the influence of parental characteristics, related learning disabilities, and even socioeconomic factors on the probability of ADHD development in children. In her article, Rydell (2010) presents her view of the situation and explores the influence of demographic factors and negative life events on ADHD. Although ADHD is more frequent among boys than girls and ADHD and oppositional defiant disorder behaviors often go hand in hand, the research of negative events, environmental stresses, and related complexities and their influence on ADHD has been scarce (Rydell, 2010). Unfortunately, researchers keep to an erroneous belief that ADHD is a hereditary disease, and do not see the need to explore other, possible explanations of the growing incidence of ADHD and its etiology in North American children. Surprisingly or not, Rydell (2010) finds that maternal education, single parenthood or step parenthood, and ethnicity (non-European descent) produce marked impacts on the development of ADHD in children. According to Rydell (2010), ethnicity is among the basic factors of influence in the development of ADHD risks. Furthermore, single parenthood and step parenthood were associated with high levels of ADHD symptoms, while negative life events had additive effects on the level of ADHD (Rydell, 2010). Statistically, 5.5% of children who have mothers with less than 9 years of education, 15% of children living with step parents, and 6.5% of children from the immigrant families are at higher risks of developing ADHD symptoms during childhood (Rydell, 2010). The combination of these factors is of primary importance: children living in immigrant single-parent families are more likely to develop ADHD than children living in native single-parent families (Rydell, 2010). Still, Rydell (2010) recognizes the moderating effects of individual factors like gender and genotypes. In other words, environment does play an important role in ADHD risks but environmental factors alone cannot explain the etiology of ADHD in children.

Milberger et al (1996) support the similar line of research and refer to the role of environmental factors in the development of ADHD symptoms: the authors try to define whether maternal smoking during pregnancy is a risk factor for ADHD. Milberger et al (1996) support the belief that “both genetic and environmental risk factors have been implicated in the etiology of ADHD. On the basis of results from family genetic, twin, adoption and segregation analysis studies, genetic factors appear to be an important part of the ADHD etiologic mechanism” (p. 1138). Milberger et al (1996) explore maternal smoking during pregnancy because the latter was always associated with the development of cognitive and behavioral problems in their children – researchers tend to agree that nicotine as the most active component of tobacco is among the basic reasons of brain damages at critical times in the child’s development. Again, the authors of the research find strong positive association between maternal smoking during pregnancy and the risks of ADHD in their children: these risks and ADHD symptoms are not attributable to their socioeconomic status, hereditary factors, or parental IQ (Milberger et al, 1996). The exact mechanisms of the positive association between nicotine influences and the development of ADHD remain unknown, but it is clear that nicotine affects a number of the child brain’s receptors which, in their turn, affect the dopaminergic system and turn nicotine during pregnancy into the candidate etiology for ADHD (Milberger et al, 1996). Nicotine is likely to result in temporary hypoxia of the unborn child and, consequentially, brain impairments that lead to the development of ADHD symptoms during childhood. Yet, these results require further investigation. As of today, the study of environmental influences on ADHD remains increasingly scarce.

Literature sources suggest that the etiology of ADHD comprises both hereditary and environmental factors, including parents’ socioeconomic status and the probability of negative life events. It is unclear how genes and environment in ADHD interact and whether environmental factors have a chance to turn into the dominant force of ADHD development in children. For many years, the psychopathology literature on ADHD was disinterested in investigating the environmental factors of ADHD, and only now are environmental influences on ADHD becoming more important and recognized. Researchers agree that in the gene-environment interaction and their influence on ADHD, genetics and hereditary factors play the dominant role. However, it is also possible that some phenotypes and genotypes are more vulnerable to environmental influences than others, and that was the subject of Waldman’s et al. (2007) research. The researchers investigated the etiology of ADHD through the prism of Gene x Environment interactions and the role of environmental factors in the development of ADHD across D2 gene genotypes. Waldman et al (2007) write that the strength and validity of environmental and genetic influences on ADHD varies across different genotypes, and the D2 genotype is more vulnerable to environmental influences than the rest of possible gene combinations. These genotypes display increased vulnerability to environmental influences, including parents’ marital status and their socioeconomic position. All these findings confirm the complexity of the ADHD etiology and the difficulties, which researchers may face when trying to distinguish between more and less important factors of ADHD. The current state of knowledge about ADHD, its environmental and genetic factors, as well as its etiology and incidence is characterized by the number of inconsistencies. Moreover, researchers face numerous barriers in their way to creating a more objective picture of ADHD.

Public perceptions about ADHD present one of the basic problems. Several researchers tried to estimate the influence of public perceptions about ADHD on the general picture and understanding of ADHD factors. It appears that teachers tend to hold erroneous beliefs about the incidence and prevalence of ADHD in their classrooms: teachers believe that (a) ADHD is not a biological condition; (b) medication is the only way to change disruptive behaviors in children; and (c) only 28 percent of teachers believe the incidence of ADHD in their classroom to be at the national level or less – most teachers tend to identify from six to fifteen percent of their students with ADHD symptoms compared with the average national 5 percent (Glass & Wegar, 2000).

African American communities display an entirely different picture. While the incidence of ADHD in North America is on the rise, most African Americans refuse to recognize the presence and prevalence of ADHD symptoms in children (Davison & Ford, 2001). These communities have a socially constructed view of ADHD, and they are less likely to diagnose and treat ADHD in their children (Davison & Ford, 2001). The current study of the incidence and etiology of ADHD is characterized by a whole range of difficulties: “the lack of an objective diagnostic test for ADHD; the lack of a gold standard measure of ADHD that is easily applicable in epidemiologic research; the lack of a systematic means to monitor the diagnosis of ADHD and the lack of consistency in case definition and how it is operationalized” (Stefanatos & Baron, 2007). As a result, it is at least incorrect and even unprofessional to take the current research findings as unilaterally correct and justified. Researchers display their willingness to take ADHD as a hereditary disease and ground their judgments on the average incidence of ADHD between 5-6% in North America. Obviously, years will pass before researchers and education professionals have a clearer picture of ADHD and its incidence in North America.

Discussion

Based on the results of this literature review, it would be correct to say that “the etiology and pathogenesis of ADHD is poorly understood” (Albayrak et al, 2010). The complexity of factors and influences on ADHD symptoms make it difficult to develop a clearer picture of ADHD etiology. Nevertheless, several conclusions can be made. First, genetic factors seem to play one of the dominant roles in the development of ADHD symptoms. Taking into account the fervor with which modern researchers investigate the link between human genetics and ADHD, the latter seems to be the product of primarily genetic influences. Albayrak et al (2008), Derks et al (2007), and Rommelse et al (2010) support and reinforce these beliefs. Really, the current state of research proves genetic predispositions and influences to be the basic source of ADHD risks and symptoms. While neurological complications and brain impairments often stem from the problems in the child’s genetic development and the child’s specific genetic characteristics, researchers believe that ADHD is nothing but the result of these complex genetic interactions.

Second, genetic predispositions are only one aspect of the complex ADHD etiology. Those who limit their view of ADHD to genetic factors distort the whole picture of the ADHD roots and underlying mechanisms. All children grow and develop in the process of continuous interaction with the rest of the world, and neglecting environmental influences on ADHD symptoms and risks is at least incorrect. Unfortunately, public beliefs and perceptions about the hereditary character of ADHD keep researchers from looking beyond the obvious. In the atmosphere of “hereditary” beliefs about ADHD, many professionals fail to expand their ADHD worldview. For this reason, the state of literature regarding the influence of environmental forces on ADHD is rather scarce. Only few researchers have resources and knowledge necessary to disagree with the public opinion about the problem, and present their own view on the ADHD etiology. Their findings confirm the relevance of environmental factors, including parents’ level of education, the marital status of parents, and even their immigration status. Women who smoke during pregnancy automatically make their children more vulnerable to the risks of ADHD (Milberger et al, 1996). It is possible to predict that other, more or less significant factors also impact the course and pace of ADHD development in children, e.g. parents’ level of education (Rydell et al, 2010). Yet, what these factors are and what role they play in the development of ADHD symptoms and complications is still unclear. Today, researchers in the field of ADHD must finally recognize that environmental factors add their share of complexity to the ADHD etiology and incidence. Genetic predispositions and genotypes alone cannot result in the rapid rise of the ADHD incidence in North America. Factors other than genetics require reconsideration and analysis, but researchers and education professionals will hardly move forward, unless they finally realize that ADHD is a complex phenomenon, influenced by a complexity of factors, not all of which are purely genetic.

One of the basic tasks is to decide how important these environmental factors are and what society can do to reduce their influence and, as a result, the risks of ADHD symptoms in children. According to Wood et al (2010), 76% of the ADHD etiology accounts for genetic factors, meaning that ADHD is hardly a solely genetic problem. Approximately ¼ of the ADHD etiology grows from the child’s environment and requires professional attention. Today, more than ever, environmental factors require professional opinion and thought. The lack of such professional attention may be responsible for the society’s failure to combat ADHD, which is fairly regarded as the most common psychopathology in children in North America (Albayrak et al, 2008). The etiology of ADHD is so complex that it is virtually impossible to distinguish between more important and less important environmental factors. Moreover, the influence of one and the same environmental factor on children with ADHD or ADHD risks may differ, depending on each child’s genotype (Waldman, 2007). In the current state of research, the debate between the supporters of the genetic and the environmental vision of ADHD persists, making it difficult to pursue objectivity and non-bias in ADHD research. As of now, it is absolutely impossible to state with confidence that ADHD is the result of solely genetic and/ or environmental factors. The information provided by researchers and their findings create a confusing image of the disorder and require further, investigation.

The situation with ADHD incidence in North America is no better: more often than not, researchers face numerous barriers in their way to obtaining the relevant statistical information. Although the data on the prevalence and incidence of ADHD in North America do not display any significant statistical deviations, different researchers refer to different statistical results. Some of them claim ADHD incidence not to exceed 5-6%, while others are confident that the rates of ADHD in children may reach 9%. 5% has already turned into the average index, which researchers use in their analyses. Again, whether these numbers are correct and can be used in professional research is difficult to define. Simultaneously, the rates of ADHD symptoms and risks differ across different communities and even different families: for example, in families with step parents, the rates of ADHD risks may reach unbelievable 15.5%, while only 6% of children with poor educated parents will be at risk of ADHD (Rydell, 2010). Given the barriers which researchers face in their striving to investigate the ADHD incidence and etiology, one cannot take and use this data without questioning its validity. Stefanatos and Baron (2007) recognize that although ADHD impacts approximately 4-12% of school-age children, these estimates may display considerable variations, ranging from 2% to almost 18%. Clinic-based samples usually generate higher rates of ADHD than population-based researches (Stefanatos & Baron, 2007). 50% of those who refer their children to mental health facilities suspect that their children have ADHD, but teachers and parents have erroneous beliefs about ADHD in their children: – very often, those who seem to have ADHD do not have its symptoms and are not even at risk of having a psychiatric disorder (Glass & Wegar, 2000). Today, when the sources of statistical data are so many and when the conditions in which these data are produced vary, one cannot define how serious the ADHD situation is and what it will take to change it for the better. The two basic tasks which researchers face include (a) to produce a coherent set of statistical data regarding the prevalence, incidence, and co-morbidity in ADHD; and (b) to engage in the detailed analysis of genetic and, more importantly, environmental factors of ADHD. Teachers and parents require better knowledge of ADHD and its symptoms. Given the complexity and confusion in present day literature, years may pass before the society has the full knowledge of ADHD, its etiology, and incidence in North America.

Conclusion

Attention Deficit Hyperactivity Disorder is the most common form of child psychopathology in North America. ADHD is characterized by increased levels of inattention, hyperactivity, and impulsivity compared with other children of the same age. The incidence of ADHD in North America varies between 4 and 12% for school-age children. These estimates, however, require detailed analysis and consideration, based on the complexity of factors that impact ADHD incidence in various population groups. In a similar vein, the current state of literature does not provide full information about the ADHD etiology: most professionals take the information about the hereditary nature of ADHD for granted and are not willing to look beyond the obvious. Yet, environmental factors do play their role in the development of ADHD factors. They add their share of complexity to the ADHD etiology and confirm that ADHD is the product of multiple influences. Given the confusion in literature about ADHD and the lack of attention to environmental factors of ADHD, years may pass before society has an objective, coherent, and relevant picture of ADHD and its rates in North America.

References

Albayrak, O., Friedel, S. & Schimmelman, B.G. & Heberbrand, J. (2008). Genetic aspects in attention deficit/hyperactivity disorder. Journal of Neural Transmission, 115, 305-315.

Banaschewski, T., Becker, K., Scherag, S., Franke, B. & Coghill, D. (2010). Molecular genetics of attention-deficit/ hyperactivity disorder. European Child and Adolescent Psychiatry, 19, 237-257.

Davison, J.C. & Ford, D.Y. (2001). Perceptions of attention deficit hyperactivity disorder in one African American community. The Journal of Negro Education, 70, 4, 264-274.

Derks, E.M., Dolan, C.V., Hudziak, J.J., Neale, M.C. & Bloomsma, D.I. (2007). Assessment and etiology of attention deficit hyperactivity disorder and oppositional defiant disorder in boys and girls. Behavioral Genetics, 37, 559-566.

Glass, C.S. & Wegar, K. (2000). Teacher perceptions of the incidence and management of Attention Deficit Hyperactivity Disorder. Education, 121, 2, 412-420.

Milberger, S., Biederman, J., Faraone, S., Chen, L. & Jones, J. (1996). Is maternal smoking during pregnancy a risk factor for attention deficit hyperactivity disorder in children? American Journal of Psychiatry, 153, 9, 1138-1142.

Rommelse, N., Franke, B., Geurts, H.M., Hartman, C.A. & Buitelaar, J.K. (2010). Shared heritability of attention-deficit/ hyperactivity disorder and autism spectrum disorder. European Child and Adolescent Psychiatry, 19, 281-295.

Rydell, A.M. (2010). Family factors and children’s disruptive behavior: An investigation of links between demographic characteristics, negative life events and symptoms of ODD and ADHD. Soc Psychiat Epidemiol, 45, 233-244.

Stefanatos, G.A. & Baron, I.S. (2007). Attention-deficit/hyperactivity disorder: A neuropsychological perspective toward DSM-V. Neuropsychological Review, 17, 5-38.

Waldman, I.D. (2007). Gene-environment interactions reexamined: Does mother’s marital stability interact with the dopamine receptor D2 gene in the etiology of childhood attention-deficit/hyperactivity disorder? Development and Psychopathology, 19, 1117-1128.

Willcutt, E.G., Pennington, B.F. & DeFries, J.C. (2000). Etiology of inattention and hyperactivity/impulsivity in a community sample of twins with learning difficulties. Journal of Abnormal Child Psychology, 28, 2, 149-159.

Wood, A.C., Asherson, P., Meere, J.J. & Kuntsi, J. (2010). Separation of genetic influences on attention deficit hyperactivity disorder symptoms and reaction time performance from those on IQ. Psychological Medicine, 40, 1027-1037.