An Investigation of the New Breed of ADHD Treatment
9 May 2011
On April 23, 2008, Vyvanse (lisdexamfetamine) received FDA approval for the adult population. The approval of this drug marked a new era in evolution of Attention Deficit Hyperactivity Disorder treatments. After decades of criticism on the rampant abuse and alleged overprescribing of amphetamine ADHD medications New River Pharmaceuticals responded by developing lisdexamfetamine, a compound that is inactive until converted to dextroamphetamine by the gastrointestinal tract. This means that Vyvanse is only effective when taken orally, reducing the ...view middle of the document...
Fidgeting, running about or climbing inappropriately, trouble enjoying leisurely activities, and excessive talking can indicate hyperactivity. Impulsivity is comprised of trouble waiting one’s turn, blurting out answers before one is finished speaking, and interrupting others. Noting 6 or more of these symptoms can make a diagnosis. With varying combinations of these symptoms, there are 3 types of ADHD that can be identified; Combined type, Predominantly Inattentive type, and Predominantly Hyperactive and Impulsive type. The methods of diagnosis for ADHD have been constantly evolving since its discovery, from merely observation to complicated clinical tests.
Clinical procedures are still used to diagnose ADHD, yet the advancement of technology now allows the physical manifestations of ADHD to be made visible with Functional Magnetic Resonance Imaging (fMRI). This technology allows doctors and researchers to gauge the levels of neurotransmitters in the brain in association with the activity or lack of activity in certain brain regions. Dr. Helen Courvoisie completed one of the first studies on ADHD using this technology. Courvoisie states, “Our data show children with ADHD had a two-and-half-fold increased level of glutamate, an excitatory brain chemical that can be toxic to nerve cells… The data also suggest a decreased level of GABA, a neuro-inhibitor. This combination may explain the behavior of children with poor impulse control”. This study measured neurotransmitter metabolites in a specific section of the frontal lobe. Toxic levels of glutamate in the prefrontal cortex and temporal lobes of children with ADHD can lead to neuronal damage, cell death, and resulting inactivity in these regions.
One theory proposes that, for those with ADHD, there is a dysfunction in the dopamine transfer system. A dysfunction in dopamine transfer suggests that while dopamine response to reinforcing stimuli occurs quickly and efficiently in the mesolimbic pathways of normal children, mesolimbic dopamine response in children with ADHD is delayed and decreased to the point that learning conditions are much slower and reinforcing stimuli are much less salient. This idea goes hand-in-hand with the Low Arousal Theory. The Low Arousal Theory suggests that, due to an inadequately functioning dopamine system, those with ADHD seek self-stimulation and extreme activity to transcend their condition of unusually low arousal.
The underlying neurobiological abnormalities that cause ADHD are understood fairly well, however the factors that bring about these abnormalities are currently under investigation. As of now, it is believed that ADHD susceptibility is linked to genetics in cohorts with environmental factors. To date no specific gene has been found to play a chief role in ADHD. However, some genes have been found to have an association with the disorder. The most predominant are genetic variations in the D4 receptor (Swanson et al., 2000) and the DAT1 dopamine...