ADHD: Biological or Behavioral
ADHD: Biological or Behavioral
By definition, Attention-Deficit Hyperactivity Disorder (ADHD) refers to a neurobiological condition that involves behavioral dysfunctions as well as cognitive distortions characterized by inattentiveness, hyperactivity and impulsiveness. Essentially, neurobehavioral feature means that ADHD has both neurological and behavioral components (Delfos, 2014, p.58). Research shows that ADHD is a common trend in children and affects 5-8% of school-age children and that boys are three times more likely to suffer from ADHD than girls (Gimpel Peacock & Holland, 20014, p.3). However, ADHD is not exclusively children’s problem with 60% of adults with ADHD exhibiting signs of inattentiveness, impulsiveness, intolerance, irritability and aggravation, which mostly occurred before age of seven years. Similar to many illnesses, ADHD is a result of a combination of factors. According to Larsson, Anckarsater, Råstam, Chang & Lichtenstein (2014), majority of studies agree 80% of ADHD cases are caused by genetic and biological factors. Family, adoption studies, twin studies and molecular genetics researches give more information which is essential in determining whether ADHD is behavioral or biological (Wood & Neale, 2014, p. 876).
A single treatment or diagnosis does not fits all cases of ADHD. With each case being different, there are three sub-types of ADHD according to the American Psychiatric Association. First, there is the predominant inattentive Type which is characterized by not paying attention to detail, easily distracted, making careless mistakes, forgetfulness, failure to pay attention to tasks, losing things needed to finish tasks and being unable to follow or comprehend instructions. An individual must exhibit at least six of these nine symptoms and a few symptoms of hyperactive-impulsive type to be diagnosed as inattentive.
The Hyperactive-Impulsive Type is characterized by inability to stay calm in quiet surroundings, continuously fidgeting, inability to focus on tasks, unnecessary physical movement, chatting too much, inability to wait for their turn, actions without thoughts-always on the go, constantly interrupting talks and have little or no sense of danger. An individual has to exhibit at least six of these signs and a few symptoms of inattentive type.
The combined type is the most common subtype and is characterized by the symptoms of both inattentive and hyperactive-impulsive types.
Family studies show that over 25% of the first-degree relatives of the families of children with ADHD also had ADHD. This was unlike, the 5% in each of the control groups which means that a child is five times likely to suffer from ADHD if a close relative mostly a parent also had the disorder (Fitzgerald, Bellgrove & Gill, 2007, p.11).
Twin studies have been conducted to determine the genetic basis for ADHD by studying large groups of both identical and non-identical twins. Fundamentally, identical twins have exactly the same genetic information while non-identical twins do not. Consequently, if ADHD is transmitted genetically, it goes without saying that both identical twins should be affected in the same way. Moreover, the concordance rate which is the probability of them both being affected should be higher than in non-identical twins. Majority of the studies revealed a concordance rate of between 70-82% for ADHD among identical twins compared to a 25-38% concordance rate for ADHD in non-identical twins (Southall, 2007, p.11).
As a basic rule, if a trait is genetic then adopted children should bear a resemblance to their biological relatives more directly than their adoptive guardians. The studies compared adoptive children with hyperactivity to their adoptive and biological parents and they showed that hyperactive children took after their biological parents more than they did with the adoptive parents in respect to hyperactivity (Buitelaar, Kan & Asherson, 2014, p.128). This is a strong indicator that genetics play an influential role on familial risk for the disorder.
Molecular Genetic Studies
While twins studies corroborate the proposition of the important role that genes play as the leading cause of ADHD, these studies do not isolate specific genes associated with ADHD. Though genetic research in ADHD is relatively new, the research has wants to investigate the specific genes responsible for transmitting the disorder and have specifically focused on the dopamine. Scientists have been able to isolate two dopamine genes, DAT1 and DRD4 and associated them with ADHD. However, even though they have not yet reached conclusive results, this is a major scientific step and it also supports that ADHD is biological (Retz & Klein, 2014, p.59).
In conclusion, even though there is no one single or specific cause of ADHD, scientists concur that it is a medical disorder that affects several areas of the brain. They have also established that the disorder mostly affects the frontal cortex responsible for decision-making functions and regulating behavior, operational memory, thinking, development and organizing. Moreover, familial, twins, adoption and Molecular Genetic Studies confirm that ADHD is hereditary. However, ADHD can also be caused by brain injuries, stoke, trauma to the head and exposure to toxic substances. Moreover, research shows that ADHD is more common in boys than girls. Nevertheless, based on the different studies one can convincingly conclude that ADHD is biological but expressed through behavior.
ADHD Epidemiology - ADHD symptom types | ADHD Institute. (2016). Adhd-institute. Retrieved 6 April 2016, from http://www.adhd-institute.com/burden-of-adhd/epidemiology/presentations-of-adhd/
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Gimpel Peacock, G., & Holland, M. (2014). Emotional and behavioral problems of young children. New York: Guilford Press.
Larsson, H., Anckarsater, H., Råstam, M., Chang, Z., & Lichtenstein, P. (2014). Childhood attention-deficit hyperactivity disorder as an extreme of a continuous trait: a quantitative genetic study of 8,500 twin pairs. Journal Of Child Psychology And Psychiatry, 53(1), 73-80. http://dx.doi.org/10.1111/j.1469-7610.2011.02467.x
Lesch, K., Timmesfeld, N., Renner, T., Halperin, R., Röser, C., & Nguyen, T. et al. (2014). Molecular genetics of adult ADHD: converging evidence from genome-wide association and extended pedigree linkage studies. Journal Of Neural Transmission, 115(11), 1573-1585. http://dx.doi.org/10.1007/s00702-008-0119-3
Retz, W., & Klein, R. (2014). Attention-deficit hyperactivity disorder (ADHD) in adults. Basel: Karger.
Southall, A. (2015). The other side of ADHD. Abingdon, UK: Radcliffe.
Wood, A., & Neale, M. (2015). Twin Studies and Their Implications for Molecular Genetic Studies: Endophenotypes Integrate Quantitative and Molecular Genetics in ADHD Research. Journal Of The American Academy Of Child & Adolescent Psychiatry, 49(9), 874-883. http://dx.doi.org/10.1016/j.jaac.2010.06.006