FACTORS INFLUENCING THE USE OF METHAMPHETAMINE BY DENTAL PATIENTS IN THE UNITED STATES anorexia, and dental carries. 1, 33 3.4. Pharmacology The lipid soluble nature of methamphetamine assists its rapid movement across the blood brain barrier initiating powerful neurocognitive reactions. Not only does methamphetamine cause an extreme rush of pleasure by releasing dopamine and norepinephrine into nerve terminals, it also inhibits the natural reuptake process, resulting lasting effects of the drug. 1, 31, 34 This process explains the lengthy half-life of methamphetamine which is 10 and 12 hours, which substantially longer than other stimulants such as cocaine(~ 90 minutes). 1, 30, 31 Rothman et al. conducted in-vitro studies finding that methamphetamine has the potential to release twice the amount of noradrenaline as dopamine, and 60 times the amount of noradrenaline release than serotonin. 35 The exponentially powerful effects of methamphetamine give insight to the extremely addictive nature of the drug. Prolonged use of methamphetamine has been shown to cause chronic health issue. After repetitive drug use, nerve terminals experience neurotoxicity caused by oxidative stress and neuro-inflammation resulting from increased intra and extracellular concentration of dopamine. 31, 34, 36 The deterioration of these terminals and depleted supply of dopamine impairs the brain’ s ability to naturally feel pleasure, resulting anhedonia. As a result, risks for methamphetamine abuse greatly rises as individuals increase frequency of use, dosage, and alter routes of administration in attempts to reach previous highs. Once common routes of methamphetamine administration such as smoking and oral ingestion fail to yield desired effects, methamphetamine users often shift to intravenously injections because of the superior
30, 31
bioavailability of the drug in the body’ s system. The elevated concentration and increased potency of intravenous administration accelerates the decline of dopomergenic synapsis while exasperating physiological effects. 30, 33, 37 Long-term recovery outcomes are adversely affected by intravenous use due to the invasive effects throughout the body. A 3-year follow up study of methamphetamine users in recovery found that individuals who injected the drug reported significantly more severe symptoms of depression than smokers and intranasal users. 38 While dosing characteristics vary between methamphetamine users, binge episodes consisting of persistent and excessive administration of the drug typically last for several days. 30 During binge episodes, individuals often suffer from anxiety, hyper-arousal, and insomnia. 1. Methamphetamine users often engage in detrimental personal health practices by consuming sugary food / drinks, and neglecting personal hygiene particularly during
1, 33, 39
binge episodes. Current research shows a strong connection between methamphetamine use and a litany of psychological issues that often stem from decrease neurological functioning. Methamphetamine damages neurological processes and is expressed via maladaptive mood, behavior and cognitions. Common psychological effects of methamphetamine include hallucinations, delusions, paranoia, psychomotor agitation, while mood disorders typically manifest as depression,
1, 20, 34
anxiety, and in some cases, bipolar disorders. Emerging research has been able to explain how the neurological effects of methamphetamine inform the psychological pathology associated with the drug. Scott et al. published an extensive meta-analysis of the neurological effects of methamphetamine use. The review incorporated 18 studies consisting of a total of 951 participants, including 487 participants with a history of methamphetamine use, and 464 normal comparison participants. The meta-analysis aimed to identify the regions of the brain, and neurological functioning that were altered due to methamphetamine use. Scott et al. found that significant deficits were associated to neurological processes related to frontostriatal and limbic circuits. The presence of methamphetamine to these regions of the brain cause cognitive deficits to episodic memory, and executive functioning. 33 Several studies within the meta-analysis highlight the harmful effects of methamphetamine use to episodic memory. Individuals who are dependent on the drug are unable to consciously recall experiences and negative symptoms associated with prior methamphetamine use. Diminished episodic memory may be a reason that the individual repeats past mistakes associated with their drug use. 31, 33 Another finding of the metaanalysis was that executive dysfunction is closely related with methamphetamine use. Participants who were dependent on methamphetamine show impairments in executive functioning involving inhibition, decision making, delayed gratification, and attention. 31, 33 Other neurological issues associated with methamphetamine addiction include psycho-motor delays and verbal-learning deficits. 37 Debilitated cognitive processes such as working memory and decision-making increase the likelihood for methamphetamine dependency, risky behaviors, and poorer overall health outcomes. Methamphetamine use has disastrous effects on the brain and body, yet there is evidence to suggest that if an individual can work towards recovery, they have the potential to have positive health outcomes. Research shows that the brain is extremely resilient. Individuals who are recovering from methamphetamine addiction have shown significant decrease of psychological symptoms, and increase in cognitive functioning. In a study involving 34 methamphetamine participants in recovery, Bagheri et al. found that after a just three weeks of abstinence, participants reported a decrease in symptoms of depression, and increase in quality of life. 40 Research indicates that not only mood disorders may be alleviated, but also neurocognitive performance has been shown to increase when in recovery. Several studies on participants in recovery found that abstinent individuals were able to improve neurological functioning close to baseline standards. 37, 41 Individuals who were in recovery, and / or had achieved abstinence from methamphetamine use displayed marked improvements in assessments
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