Effects of Stimulants on the Brain

Effects of Stimulants on the Brain

Kimberly K. Jones

Liberty University

Author Note

        Kimberly K. Jones, Social Work student, Liberty University.

        Correspondence concerning this article should be addressed to Kimberly K. Jones, 34886 Morton Road, Langsville, Ohio 45741.  E-mail: kkjones3@libery.edu

Abstact

Psychostimulant use can cause changes in the brains.  These changes are different for children and adults.  Psychostimulant use will affect the brain differently, whether the medication is used at prescribed or whether taken in much larger quantities than recommended. The misuse of stimulants can be very dangerous and change the way your brain functions. The brain may or may not return back to normal after the use of the stimulant has been stopped.  This paper compares the use of legal psychostimulants to the misuse of psychostimulants.

Keywords: stimulants, drugs, the brain structure, methylphenidate, methamphetimen

        Merriam Webster dictionary defines a stimulant as 1. An agent (as a drug) that produces a temporary increase of the functional activity or efficiency of an organism or any of its parts 2. An alcoholic beverage – not used technically.  The psychostimulant provides some great benefits as an effective medicine for a range of disorders, they are also often abused and misused as illicit substances of abuse.  Stimulants come in a variety of forms such as amphetamines, cocaine, and methamphetamines.  Prescription medications for attention deficit hyperactivity disorder are also often stimulants.  Improper use of stimulants can lead to hostility, paranoia, and even some psychic symptoms.  Some of the symptoms of improper stimulant use can be unsafely elevated body temperature, irregular heartbeat, heart failure, and seizures.  These symptoms occur when the brain function has been modified to adjust to the use of stimulants.  If stimulants are used as prescribed they can better help people have better control of themselves and their behaviors.  If they are misused the way some do, the activity of the brain changes and doesn’t always go back to normal.  What is the differences in the way the brain functions on prescribed psychostimulants versus misused psychostimulants?

        Attention deficit hyperactivity disorder is defined by age inappropriate, inattention, impulsiveness, and hyperactivity.  Attention deficit hyperactivity disorder is most associated with inhibition, attention, working memory, and timing deficits, underpinned by functional magnetic resonance imaging abnormalities on the underlying inferior frontal cortex and dorsolateral prefrontal, striatal and parietal regions, and networks, which are structurally abnormal (Rubia, et al. 2013). Psychostimulant medications have medical benefits for a range of disorders, when used correctly.  The primary drugs used to treat attention deficit hyperactivity disorder are amphetamine and methylphenidate (Heal & Smith, 2014).  A key challenge in using this medication is balancing the risks and the benefits.  All stimulants currently controlled under the United States Controlled Substances Act have similar pharmacological activity as the prototypical stimulant D- amphetamine.

        The major classical molecular mechanisms by which psychostimulants produce their effects in the brain involves alteration on monoaminergic system, oxidative stress, mitochondrial dysfunction and excitotoxicity (Goncalves, Baptista, Silva, 2014).  The most effective psychostimulant medication used for treating attention deficit hyperactivity disorder is the catecholamine agonist, methylphenidate.  Methylphenidate, at therapeutic doses, blocks 60% to 70% of striatal dopamine transporters.  The particular dopamine transporters are abnormally low in medication-naïve attention deficit hyperactivity disorder patients (Rubia et al. 2014).  In other areas, like the frontal lobes, “methylphenidate blocks 70% to 80% of norepinephrine transporters, which reuptake both dopamine and norepinephrine, leading to increased extracellular catecholamine levels” (Rubia et al. 2014).  Underlying mechanisms of action without confounds of secondary effects of improved behavior under chronic treatment were discovered by using functional magnetic resonance imaging studies of acute effects of psychostimulants.  There were randomized placebo controlled functional magnetic resonance imaging studies that found increased activation in predominantly right, but also left, inferior frontal cortex during tasks of sustained attention, inhibition, and time discrimination; in the parietal regions during sustained attention, error monitoring, and interference inhibition; the cerebellum during attention, time discrimination, and interference inhibition; and striatum during reward and response inhibition (Rubio et al. 2014).  The studies in chronically medicated attention deficit hyperactivity disorder patients found that an acute clinical stimulant dose relative to off medication enhanced significantly the bilateral media frontal activation during an emotional Stroop, deactivated cingulate default mode regions during a cognitive Stroop task, or had no effect during working memory (Rubia et al. 2014).  “Region of interest functional magnetic resonance imaging studies focusing on frontal and striatal regions found that compared with atomoxetine and placebo, methylphenidate had no effect during working memory but significantly enhanced right inferior frontal cortex activation during motor inhibition and during time discrimination together with atomoxetine” (Rubie et al. 2014).  Functional magnetic resonance imaging studies in chronically medicated attention deficit hyperactivity disorder patients found that a methylphenidate dose compared to patients off medication enhanced activation in inferior, medial frontal and anterior cingulate cortex and striatum.  Whole brain analysis does not restrict the search volume and hence do not bias findings toward prior hypothesized regions.  Results of the whole brain analysis of functional resonance imaging comparison between methylphenidate and placebo found multivariant analysis of variance showed “no significant differences between control subjects and patients under each drug condition in the extent of maximum rotation” (Rubia et al. 2014).  In normalization effects, control subjects and patients under the placebo had no difference in performance, however patients under methylphenidate showed slightly shorter reaction time that the control subjects.  “Boys under the placebo had under activation in bilateral inferior frontal cortex, left middle temporal gyri/inferior temporal gyri reaching into inferior parietal lobe, and right anterior cerebellum/fusiform gyrus.  Boys under methylphenidate showed reduced activation in the same left middle temporal gyri cluster but not anywhere else.  Patients showed enhanced activation compared with control subjects in left posterior cerebellum/posterior cingulate cortex and in right superior temporal gyrus, reaching into posterior insula and putamen.  There was also a small cluster in rostral anterior cingulate cortex” (Rubia et al. 2014).  In the end, after the completion of all testing, the most consistent effect stimulant medication and of methylphenidate, is increased activation of right inferior frontal cortex, a key region of cognitive control.

        While stimulants can provide great medicinal benefits to treat a wide range of disorders, they are still easily, widely, misused and abused as “illicit substances of abuse” (Heal & Smith, 2014).  The abuse of psychostimulants is not only illegal, but it is very dangerous.  Psychostimulant abuse poses a serious public health concern due to its high potential for addiction and the risk of neurological impairment (Goncalves et al. 2014).  Drug taking is considered to be an impulsive and compulsive action.  While there are many different illicit psychostimulants, this paper will primarily discuss methamphetamine.