Biology 202
2002 First Paper
On Serendip

For a typical person with Attention Deficit Hyperactivity Disorder (ADHD) sitting down to do a task such as homework can be agonizing, the physical act of staying in place, being as difficult as concentrating on the work. The person with ADHD may go on in life to have social problems because symptoms such as hyperactivity, inattention, and impulsivity, are mistaken as laziness or self-centeredness (14). The problems of ADHD often develop further manifesting as compulsive disorder, depression, school and job failure, relationship trouble, and substance addiction (5). ADHD is a psychiatric disorder, first documented by the medical society in 1902, that is diagnosed in 3%-5% of school age children (14). Although, there have been many changes in the understanding of the still puzzling disorder, the diagnostic criteria now given for ADHD are given by the DSM-IV, which provides lists of symptoms for three types. The person can have the hyperactivity type, the inattentive type, or a combination of the two, which is a third type. In order to be diagnosed with either type the person must express six of the symptoms from one category or the other, and the symptoms must have been present for at least six months. The person has the combination type if they have six symptoms from both categories (8) .

Many of the symptoms listed in the DSM-IV make ADHD sound more like a personality type rather than a disorder. A person has a 30% chance of having ADHD if a sibling or parent has the disorder, which is not surprising considering personality types also tend to run in families (1). Approximately 2/3 of the children diagnosed with ADHD are comorbid, but then the other 1/3 are otherwise deemed normal (6). Many people with only ADHD may have attention and memory problems, but then also have characteristics that can be looked at in a positive light. For instance these same people are often spontaneous, creative, and outgoing (4). In a world where most of the successful are those who can sit behind a desk for lengthy hours at a time, there are naturally going to be people who have great difficulties doing well in this life style. To what point should people be able to conform to the sit, stay, and focus lifestyle before they are labeled with a disorder?

There has been a great deal of studies done in attempts to find the neurobiological brain differences between normal people and those diagnosed with ADHD. According to MRI and other studies it is believed that a primary problem area for those with ADHD is the frontal lobe, specifically the cortex, an area with functions such as attention, concentration, memory, and learning (12). The frontal lobe is also an area where the neurotransmitter dopamine is synthesized and used. There seems to be lower levels of dopamine in the frontal lobes of those having ADHD. Another study shows 48% higher DOPA decarboxylase activity, which breaks down dopamine, in the right midbrain of those with ADHD (10). Stimulants such as Adderall are thought to increase dopamine levels in this area of the brain by decreasing re-uptake (11). Studies show that 70%-80% of children with ADHD respond positively to the stimulant medications. Other drugs that have been used to treat ADHD include antidepressants that have effects on the neurotransmitters, norepinephrine and dopamine. The diagnosis of ADHD and the prescription of medication to treat ADHD are on the rise (8). Is this because more people are educated about the disorder and are seeking treatment, or is this because many parents are abusing the disorder as an excuse for poor parenting or a child that is not motivated to sit and study? Although, it seems the latter could sometimes be the case, many of the new cases are adults who were never diagnosed because the disorder and the treatments were not as publicly known as they are today. New research shows that 2%-4% of adults have ADHD(). Also more girls that were overlooked, because on average they are naturally less hyperactive then boys, are now being diagnosed (14).

Some of the newer studies supporting differences in the ADHD brain are as follows. Quantitative EEG (QEEG), a highly sensitive and common test for abnormality, shows that children with ADHD have abnormal QEEG scans of up to 80% higher than in normal children. The most abnormal areas are in the thalamocortical and septal-hippocampal pathways located in the frontal part of the brain (3). Another study that suggests differences in the brain of people with ADHD involves DRD4, the dopamine D4 receptor gene. The study suggests an association between the gene and ADHD but the connection is still unclear (13). Perhaps this study will one day reveal the reasons behind lower levels of dopamine in those with ADHD. There was also a study implemented to observe differences in the working memory of those with ADHD and those without. A functional neuroimaging device, positron emission tomography (PET) study, was used to compare regional cerebral blood flow changes in the areas related to working memory. Although, the normal people had more cerebral blood flow change in the frontal and temporal regions, the people with ADHD had changes in blood flow over a larger area, with most of the change focused in the occipital lobe (2). This is important because it suggests that the ADHD brain uses other methods to try to overcome the impaired ability to focus on specific tasks or stimuli. PET studies have also given evidence to support decreased glucose levels, and therefore activity levels, in the frontal regions of the brain during learning for many with ADHD (7). The National Institute of Mental Health (NIMH) is in the process of recruiting volunteers for many new studies to be done concerning ADHD. These studies will be used to gain more knowledge about the biological basis of ADHD. Studies include, more "Brain Imaging of White Matter in Children", "Study of ADHD Using Transcranial Magnetic Stimulation", and "Biological Markers in Childhood Psychiatric Disorders (15)(16)(17)."

There are a lot of neurobiological differences between the ADHD brain and a normal brain supporting that those diagnosed with ADHD do have a disorder rather than a hyperactive or inattentive personality type. Regardless, personality difference or disorder, those with the symptoms will certainly have a difficult time successfully conforming in today's society. People diagnosed with ADHD have been shown to have deficits in executive functions of the brain, which are responsible for "activating, organizing, integrating, and managing other functions", such as learning memory (9). Executive function is highly important for success in life, and therefore, if the symptoms were before a personality, the personality is now dysfunctional in this society and constitutes being called a disorder. The demands and structure of social, educational, and occupational life will present more of a challenge for those with ADHD than those without, and these people should be given the same chance to succeed if possible. Medications such as stimulants and antidepressants, as well as lessons on how to deal with the symptoms are being used to help people with ADHD conform to the societal norm. Hopefully the many planned and already implemented ADHD studies will bring further insight into the differences of the ADHD brain. This further understanding will foster new ideas of ways to help the people who many times cannot seem to sit still and be calm, and the people who just cannot seem to stay focused, better be able to sit, listen, and concentrate.

References

1) "Frequently Asked Questions About ADD", Article from the National ADDA World Wide Website

2) "Alterations in the Functional Anatomy of Working Memory in Adults with ADHD", An article from The American Journal of Psychiatry

3) "The Clinical Role of Computerized EEG in the Evaluation and Treatment of Learning and ADHD in children and Adults" , An article from The American Journal of Psychiatry

4) "Close Relationships, Intimacy, and ADHD" , Article From CHADD website

5) "Adult ADHD and Social Skills: What Does Everybody Else Know that I Don’t?" , Article from CHADD website

6) "Fact Sheet: ADHD" , Article from the American Psychiatric Association

7) "What Causes ADD?" , Article from ADDA

8) "DSM IV for AD/HD" , Article from the Mental Health website

9) "ADD/ADHA: Reticular Activating System, Neurological Issues with ADD/ADHD Discussed" , Article from About.com

10) "High midbrain F DOPA Accumulation in Children with ADHD" , Article from The American Journal of Psychiatry

11) "ADHD Gets Some Attention" , Article from Neuroscience for Kids, off the Serendip website

12) "Hypofrontalityin ADHD During Higher-Order Motor Control: A Study With Functional MRI" , Article from The American Journal of Psychiatry

13) "Meta-Analysis of the Association Between the 7-Repeat Allele of the Dopamine D4 Receptor Gene and ADHD" , Article from The American Journal of Psychiatry

14) "CHADD Fact Sheet On ADHD Adult Symptoms" , Article from the CHADD website

15) "MRI Brain Imaging of White Matter in Children" , A current Study being carried out by NIMH

16) "Study of ADHD Using Transcranial Magnetic Stimulation" , A current Study being carried out by NIMH

17) "Biological Markers in Childhood Psychiatric Disorders" , A current Study being carried out by NIMH

| Forums | Serendip Home |