Introduction
The use of stimulants such as amphetamine (AMPH), cocaine, marijuana, and so on is considered affecting a person’s memory. Some of them, including Ritalin or Adderal, tend to become popular in clinical settings as recreational drugs. However, their impact may be adverse in case of abuse or illegal use. In this regard, it is essential to discover both the positive and negative effects of amphetamines and other stimulants along with their relations with human memory. The scope of the problem of stimulant abuse is quite important in nowadays medicine since the application of amphetamine is not explored in an in-depth manner. While some studies reflect a rather beneficial impact of the mentioned stimulants and consider future researches, others provide convincing arguments, pinpointing that stimulants are likely to destroy working and long-term memory.
This paper will start with the provision of the basis for the problem upon which it is expected to create a thorough literature review by focusing on the recent evidence. The discussion section will present credible findings and their consideration in terms of the identified problem supported by the critical analysis. Ultimately, a brief summary and conclusions will be provided in order to synthesize the results.
Background
AMPH is one of the most powerful stimulants that have ever been created. Initially, this substance was created with good intentions, such as the treatment of chronic alcoholism, obesity, and depression. In the US, it is prescribed for attention deficit hyperactivity disorder (ADHD) in the course of such medications as Dexedrine and Adderal (Calipari & Ferris, 2013). The working mechanism of AMPH focuses on the increase of dopamine that is responsible for motivation and joy – the findings of several studies confirm this effect (Calipari & Ferris, 2013). Amphetamine causes the body to produce more of this neurotransmitter, it even facilitates its passage through the cytoplasm inside the cell, lubricates the vesicles in which the dopamine is transported.
As a rule, Adderal is prescribed for the treatment of ADHD disorder – a neurobehavioral state manifested in the form of inattention, hyperactivity, and temper. This disease was included in the Diagnostic and Statistical Manual of Mental Disorders of the United States Nomenclature of Mental Disorders in 1987, and was observed mainly among children. In recent decades, it has been diagnosed more and more often. Thus, according to the Centers for Disease Control and Prevention (CDC), in the 1990s, approximately 3-5 percent of school-age children (about 600,000 students) were attributed to the mentioned disease (Calipari & Ferris, 2013). By 2013, this figure reached 11 percent, and it continues to grow along with the number of prescribed stimulants. For the most part, it is Ritalin, which, in many cases, had to be taken several times a day. In 2013, already 3.5 million children took stimulants, and Ritalin was replaced by Adderal that was officially released to the market in 1996 as a new and improved option for patients with ADHD, which effects are regarded as lasting longer.
Today, Adderal is distributed on many campuses, while students accept it both per a doctor’s prescription and without it (Ciccarone, 2011). Not in the majority, yet in many schools, there appeared the so-called markets for the illegal trade of this drug. In fact, according to a study published in 2009 in Molecular Psychiatry journal, in 2004, the use of stimulants without a doctor’s prescription was the second most common form of illegal drug use in colleges (Berman, Kuczenski, McCracken, & London, 2009). The greater popularity was gained only by marijuana. Little is known about what happens as a result of years of use of the Adderal during college and after graduation, along with all the experiences of youth. To date, there are insufficient studies highlighting the long-term effect on those who take this drug.
Likewise, Adderal, Ritalin (Methylphenidate) increases the production of dopamine in the brain, which improves attention and concentration. Unlike Ritalin, this agent has fewer side effects, in particular, because of a lower dosage, they appear less often and pronounced. Dosage is selected individually; in most cases, it is 40 mg, similar to Ritalin, but in the US, they are used in higher doses. Dexedrine includes, like Adderall, dexamphetamine, and has no special advantages over other similar stimulants. Focalin is an isomer of the active substance of Ritalin, but with a different molecular structure. Changing the structure allows reducing the dose in comparison with Ritalin in two times. As a result, side effects are less pronounced. The usual form of the drug lasts four hours in the form of XR, like LA Ritalin, with a slow release of the active principle – for 12 hours.
Speaking of some other stimulants that are used to improve attention and behavioral patterns in general, it is essential to note cannabis that is obtained from the hemp genus Sativa or Cannabis indica that similar to nettles. It grows wild in many countries and contains cannabidiol acids, the derivatives of which can be used both for therapeutic and recreational purposes. When utilizing cannabis, both psychoactive and physiological effects may occur.
In its turn, cocaine is a drug in the form of powder, and it is usually used with sugar, novocaine, amphetamine, and other drugs (Kelley, Anderson, & Itzhak, 2007). The dependence on cocaine develops quickly and is strong enough. Obtained from coca leaves, cocaine was originally synthesized as an anesthetic. Nowadays, it is recognized as harmful because it physiologically stimulates the nerve endings located in the brain, tracking changes in the body, and causing euphoria, which leads to addiction (Kelley et al., 2007). After cocaine buzz, there comes a deep depression, the feeling of irritability, and an intense desire to take even more drugs. Appetite and sleep disappear, the pulse rises, as well as spasms and convulsions, reduce muscles. A person tends to behave like a paranoid by showing anger and anxiety. Regardless of the dose, cocaine increases the likelihood of heart attacks and causes respiratory failure.
It is also essential to define what exactly short-term memory, working memory, and long-term memory are. It seems more appropriate to explain the mentioned concepts drawing on examples. The evidence shows that patients with brain injuries may experience difficulties in performing one type of task, while others that require the participation of working memory are solved quite simply and do not require special efforts (Ciccarone, 2011). For example, they can repeat letters that they hear but cannot repeat them in the given order sue to difficulties with concentration. Thus, one can agree with the statement that working memory performs two different types of tasks. Some scholars believe that the concepts of short-term and working memory are synonymous. However, according to the majority of researchers, they function differently.
Short-term memory is characterized by a relatively short period of storage of information, which is lost due to the effect of a temporary factor or due to the receipt of new information. The long-term memory stores information about different events and the amount of information that can be stored in long-term memory is almost unlimited (Ciccarone, 2011). Due to long-term memory, one can remember, for example, an event or object, and then switch the attention to something else. In a few minutes or years, one can easily extract this information from memory. Working memory is based on other mechanisms. Working memory, according to the above classification, performs operational tasks that require certain manipulations (Ciccarone, 2011). The information stored in the working memory is constantly in the focus of one’s attention as it is usually used to store information in an active state for a few seconds, while long-term memory can store information for several years.
Statement of Methods
The literature review is a critical search for an analytical framework that one can use to test a hypothesis or to systematically examine a set of problems. The purpose of this literature review is to demonstrate familiarity with what is already known in terms of the topic of amphetamine and stimulants’ advantages and disadvantages as well as their effects on memory. The review will cover the subject areas of the prevailing assumptions that have been developed, the opposing opinions, and their criticism. The key method to gather the required data will be the search for PubMed scholarly articles.
First, the attention will be paid to those sources that most likely contain a summary or overview of key questions on the research topic. Having selected those sources that appear to be directly related to the subject of the research, the underlying arguments contained in them will be analyzed. After the data collection, it is necessary to systematize, analyze, and synthesize the material in such a way as to obtain a clear and structured report on the results of the research and also to present the conclusions made based on them. Given that the review of literature is a critical evaluation of the previously published academic works, it is extremely important to correctly indicate the sources that a researcher refers to in the review. To ensure the above point, the American Psychological Association (APA) rules for the correct citation will be utilized.
Body
Amphetamine
According to data received in 2007 by the US government, over 1.6 million Americans in the past 12 months have taken stimulants by the prescription for non-medical purposes. Such legal medications included methylphenidate (Ritalin), amphetamine (Adderall), and modafinil (Provigil). On some campuses, up to 25 percent of students admitted that they used these stimulants. In an online poll among the Nature readers in 2008, more than 20 percent of 1,500 respondents from 60 countries indicated that they were taking methylphenidate, modafinil, or beta-blockers, the latter in cases of fear of public speaking. As the most frequent reason for taking medications, the need to increase the concentration of attention was indicated.
Amphetamine briefly improves intellectual abilities, especially short-term memory. There are many studies on this subject; one of them was held not so long ago, in 2015. Figure 2 presents the evidence that low doses of stimulants act solely as cognitive enhancers and are virtually devoid of side effects (Spencer, Devilbiss, & Berridge, 2015). In another research conducted by Wood, Sage, Shuman, and Anagnostaras (2014), cocaine, amphetamine, caffeine, and modafinil were compared at various dosages. It confirmed the positive cognitive effects of psychostimulants at low doses and the high incidence of side effects at high doses. In particular, the authors noted that amphetamine improved the working memory of participants based on the testing according to Stroop tasks (Wood et al., 2014). In both control and schizophrenia groups, the mentioned stimulant enhanced language production.
Amphetamine presents great opportunities for treating ADHD in Western countries. The use of psychostimulants during the admission in such patients improves the functioning of the brain and stimulates the development of nerves. For instance, Huang and Tsai (2011) report that the course of taking amphetamines for two years in ADHD patients does not lead to brain damage, but rather, they develop no dependence on this drug (Table 3). These authors focus their attention on the fact that many studies explore only the short-term impact of stimulants on patients diagnosed with ADHD. In this regard, they conduct long-term research to reveal any positive or negative effects. As argued by Huang and Tsai (2011), stimulants were assumed to be effective within 24 months of their application to children with ADHD. At the same time, they were accompanied by a few or no side effects that were quite tolerable.
The increased productivity, endurance, reduced response time, and improved memory may also be noted among the advantages of taking amphetamine in medication dosage. In sports and extreme situations, such issues seem to be especially important. Ballard, Gallo, and de Wit (2014) examined 31 people, the average age of whom was 22 years. They have a low level of alcohol consumption, and ten smokers were involved. They were divided into three groups by drug consumption, including placebo, 10 mg amphetamine, and 20 mg amphetamine (Ballard et al., 2014). Testing itself was quite interesting and revealing, from which it is possible to make far-reaching conclusions. The essence of this study is that people had to memorize words and pictures, which, in turn, were divided into neutral, positive, and negative.
The results of the above study are impressive and make one ponder over the potential impact. The fact that amphetamine improves short-term memory did not surprise anyone, but there was almost no reaction to neutral words and pictures (Ballard et al., 2014). If amphetamine is not able to make a person remember something that is not interesting to him or her, then, most likely, no stimulant can. The authors suggest that this probably, means that as a stimulant, amphetamine affects only with regards to the issues that are of interest to a person. According to Ballard et al. (2014), there is no impact of dextroamphetamine (AMP) on emotional memory retrieval, yet the mentioned stimulant increased false recognition cases along with intrusions. In this regard, one may state that memory retrieval errors may be caused by the therapeutic doses of AMP.
Along with the identified advantages, the existing evidence provides several insights on the disadvantages of amphetamine. First of all, it is essential to clarify that positive effects are possible with the normal functioning of a human body and clinical dosages. The fact that amphetamine is prohibited in almost all countries leads to the most negative outcome – the bad quality of what is sold illegally (Wang et al., 2013). Proven by many studies, amphetamine causes addiction – the longer it takes, the more tolerance is developed. To achieve the former effects, more substance is required that leads to the initial development of psychological dependence and than – physical.
The general malfunctioning of the body can also be specified as a negative impact of amphetamine. From the mechanism of action, it is clear that this stimulant increases the concentration of dopamine, norepinephrine, and serotonin as well as makes significant changes in the biochemistry of the brain. With amphetamine, the brain and memory processes, along with the dopaminergic system, will break down, expressed in mood swings, impaired motor skills, and a lack of any motivation for activity (Wang et al., 2013). The violations in the circulatory system compose another adverse effect of amphetamine-containing medications. There are such sores as tachycardia and hypertension, while people often underestimate cardiovascular diseases. Blood performs extremely important functions as it delivers nutrients to the cells and cleans them. Therefore, the failure in this system is likely to worsen the working memory and long-term memory as a result of deteriorated circulation.
Methamphetamine
Chronic use of methamphetamine significantly alters all functions of the brain. Noninvasive studies of the human brain have shown changes in the activity of the dopamine system, which are associated with slow motor skills and violation of verbal training. Recent studies among people who chronically use methamphetamine also revealed serious structural and functional changes in the brain-related areas of emotions and memory that can explain many of the emotional and cognitive problems that are observed with chronic abuse of methamphetamine.
The long-term abuse of methamphetamine can also lead to dependence – a chronic recurrent disease characterized by compulsive drug search and use, which is accompanied by molecular changes in the brain. Some of these changes persist for a long time after the end of methamphetamine use. However, restorative changes can be observed after long periods of complete abstinence from drug use (approximately one year). Although it is no longer a surprise for the scientific world that amphetamine-type drugs have a specific effect on the system for the formation and storage of memories, no one has seriously investigated this issue so far. Nevertheless, it is possible to carry the conclusions about the unexpected features of these drugs from the existing literature.
The biologists from Washington State Universities (WSU) and Calgary (U of C) have experimentally identified unusual positive properties of the psychostimulant methamphetamine drug (Kennedy et al., 2010). Snails called Lymnaea stagnalis were utilized as the participants of the study. The most interesting and unexpected of the whole series of experiments was the experience of studying the influence of methamphetamine on the formation of long-term memory (see Figure 1). The group of snails was temporarily placed in water with a dissolved drug for a while, after which they were transferred to a normal environment with limited oxygen concentration, where the animals were “trained” not to use pneumostomes (Kennedy et al., 2010). The results are thought-provoking: even after a day, invertebrates “drug addicts” remembered perfectly well what they were taught by the biologists. In the natural environment, the long-term memory of L. stagnalis lasts only a few hours. This was confirmed by an attempt to teach the same trick as a control group without methamphetamine.
In their turn, the neurobiologists from the Ellen Scripps Research Institute in Florida and the University of North Carolina tried to eliminate the so-called “narcotic” memory pharmacologically, which can help in the fight against drug addiction (Young et al., 2014). During the study, mice were given methamphetamine, combining the drug with the effects of atypical stimuli for their life. After two days (while a new memory was fixed), a drug was introduced that caused the destruction of actin, the protein playing an important role in memory consolidation. As a result, mice forgot about the narcotic experience because this memory was formed separately from other memories (Young et al., 2014). The erasure of these memories as possible without provoking total retrograde amnesia that provides the ground for conducting further research, thus contributing to the theory of eliminating sensitive memories with the help of stimulants.
Marijuana
Marijuana is one of the most widespread recreational drugs in the United States, which is especially popular among young people. The supporters of marijuana often claim that it is a safe drug that does not lead to addiction. In contrast, the opponents call it a drug and consider that the use of marijuana is dangerous (Tamm et al., 2013). In recent decades, cannabinoids are utilized for mental health problems and pain relief as an alternative treatment option. Nevertheless, its safety and effectiveness are not fully confirmed, and its use remains controversial.
Some studies show that marijuana improves cognitive ability and can be useful for the treatment of ADHD and the overall increase in cognitive functioning. Hodzhev et al. (2012) argue that those who smoke marijuana every day for at least three years have a hippocampus of an irregular shape. That is why smokers show poor results in tests for long-term memory and cued visuomotor tasks. The longer a person chronically smokes this drug, the stronger the shape of the hippocampus. It seems appropriate to pinpoint that the hippocampus is a part of the brain which is responsible for emotions and memory, in particular, for the transition from short-term memory to long-term memory. It is assumed that this site is more susceptible to cannabis influences than other parts of the brain (Hodzhev et al., 2012). The deviations from the normal form may indicate damage to the site, including changes in the structure of neurons, axons, and their supporting environment.
The authors of the recent study noted that the participants, who described themselves as chronic smokers, showed significantly worse results in a number of cognitive tests such as the study of new material, abstract thinking, information processing speed, memory tests, and concentration of attention (Hodzhev et al., 2012). However, when the researchers took into account abstinence from the use of marijuana, the difference in cognitive abilities between marijuana users and non-smokers disappeared. The cognitive abilities of young marijuana smokers completely recovered 72 hours after abstinence from marijuana (Hodzhev et al., 2012). The results of this study demonstrate the opposite opinion on the use of marijuana as a treatment option. In particular, one may suggest that further research is needed to understand the impact of marijuana after its abstinence.
Other studies reveal that the use of marijuana has no effect on cognitive abilities and even worsens the condition, especially if a person started using it at a young age. More importantly, some evidence suggests that the use of marijuana has dangerous side effects and that people who use marijuana as a treatment for ADHD are self-medicated. There is no conclusive evidence that marijuana helps in relieving symptoms. The study by Morgan, Schafer, Freeman, and Curran (2010) shows that marijuana causes negative consequences such as the violation of mental development in children and adolescents and problems with attention, training, and long-term memory. The mentioned study also illustrates that the side effects of using marijuana in children are worse, and they can outweigh any potential benefits (Morgan et al., 2010). Since a child’s brain is not completely developed, the use of marijuana may inhibit neurological development and lead to adverse cognitive effects.
The prolonged use of marijuana may lead to the partial impairment of cognitive functions, the ability to learn and remember, motivation, perception of the environment, and coordination of movements (Dougherty et al., 2013). In a teenager, regular smoking of marijuana may cause working memory destruction and a different degree of self-isolation from social, family, or school life. Dougherty et al. (2013) claim that in this stage, marijuana consumption makes a particularly disadvantageous impact on the body since the brain is at the phase of its formation. First of all, it concerns the active smoking of marijuana until 15 years Dougherty et al. (2013). The short-term memory and working memory suffer the most and other functions of the brain – to a lesser extent (see Table 2). For example, in a country where marijuana is popular, the number of road accidents exceeds the limit. Marijuana weakens the concentration of attention, and a driver admits banal mistakes: he or she drives to the red light, brakes too much, falls asleep at traffic lights or distracts to music or talks on his mobile phone. This leads to accidents with human casualties.
Cocaine
The increased overall mental activity seems to be the most noteworthy advantage of cocaine as a stimulant. It seems to a person that all his or her abilities have been revealed, memory has improved, and the ability to make decisions has become aggravated. When intoxication passes, it turns out that allegedly acquired knowledge has disappeared, and, in general, a person has done a lot of unintelligent things (Ciccarone, 2011). The detailed complications may be observed in Table 1. Cocaine causes an intensification of brain activity and exacerbates the perception of even trivial issues. In other words, it stimulates the working memory.
A person feels smarter and more confident, but since it does not become smarter, but as the dose increases, on the contrary – there is a phenomenon that seems to be a flight of ideas (Ciccarone, 2011). For instance, the recorded files show that cocaine conversations sound extremely chaotic. A small dose of cocaine creates an artificial mania and a state of accelerated thought process, as stated by Kelley et al. (2007). With increasing dose, the amplified mental productivity becomes disordered, and a false sense of super-abilities occurs. At this point, the disruptions seem to be the typical indicators of drug dependence.
Molecular biologists from the National Institute of Health in Rockville and the Miami University School of Medicine focused their attention on analyzing the work of genes in the hippocampus (Zhou, Enoch, M. A., & Goldman, 2014). This area of the brain is responsible for translating information from short-term memory into long-term memory, and it also participates in the formation of drug dependence. A preliminary analysis of 16,000 genes working in the hippocampus made it possible to isolate the 1994 gene, whose activity was impaired in people who are addicted to cocaine, and 1,275 genes that malfunction in the brain of alcoholics (Zhou et al., 2014). Both cocaine and alcohol make it difficult to form methylated form of this histone, which reduces the level of work of many genes – this has been reliably ascertained by the number of mRNA molecules.
It was revealed that cocaine suppresses the Dnmt3a gene and deactivates depression. According to Zhou et al. (2014), under the influence of the drug, neurons form a network of additional thin spines that protect the cells from the action of the drug. It is worth noting that under cocaine, neurons only grow thin dendritic spines with the increase of which depression intensifies. What happens immediately as soon as the direct action of cocaine ends. Consistent with the above study, the acute memory loss is noted in smokers of potent cannabis with a low level of cannabidiol who have a higher risk of developing an acute memory loss (Zhou et al., 2014). It is known that these processes even convey data to other sectors of the brain, yet they die faster than others. Therefore, it is impossible to rely on long-term memory for either cocaine-dependent or suffering depressions.
Children with ADHD and Stimulants’ Impact
The most common way to treat ADHD in children is medication as it increases the amount of dopamine in the synapses of the brain. Associated with amphetamine and other stimulants, they are called drugs that encourage the central nervous system (Huang & Tsai, 2011). The importance of these drugs cannot be overestimated since they are considered one of the most effective psychopharmaceuticals available today. Half an hour after admission, children become calmer, they tend to be less hyperactive and more concentrated. The long-term follow-up shows that such treatment is almost harmless. The drug does not cause permanent addiction, and the brain develops normally.
One of the positive aspects of drug treatment is improving working memory. In particular, a child swallows the pill, and his or her working memory increases by about ten percent or half the standard deviation in the population speaking in statistical terms (Huang & Tsai, 2011). This enhancement is noticeable both in children with ADHD and those without it. In fact, the effect of microscopic doses of amphetamine is repeated. It seems that this is explained by the effect on dopamine. Thus, the medications that block dopamine receptors worsen working memory, and drugs that stimulate dopamine receptors improve it.
On the other hand, sceptics argue that no one knows what the consequences of the prolonged drug exposure are. Indeed, a control group on which data can be verified is essentially not that the drug was clinically tested 10-15 years ago, when the prescribed doses were significantly lower (Huang & Tsai, 2011). To date, it is possible to note that drug therapy has become more intense, while an uncontrolled use of such drugs proved to be leading to drug addiction. The opponents of drug treatment believe that there is an alternative to carry out educational work among parents and teachers so that they better understand and correct the behavior of children with ADHD.
If one considers the failure as a mismatch between the requirements that are imposed and the ability to meet them, then students with disruptions in working memory should reduce the work memory load (Tamm et al., 2013). In practice, this means developing a special program for children diagnosed with ADHD. These well-known ideas were expressed repeatedly and formulated differently. In Canada, the initiative group called gathered the information on how to cope with ADHD without stimulants (Tamm et al., 2013). For example, the following is what they advise: to give one task at a time, use different forms of visual assistance, et cetera.
Discussion
What exactly can be improved? As it is shown by the above literature review, amphetamine and other stimulants may provide the improvement in working and short-term memory, while they are likely to affect adversely on long-term memory. In turn, the improvement of short-term and working memory presets the opportunity to improve the so-called mobile intelligence – the ability to think logically and solve problems without having a similar previous experience. Therefore, many students prefer taking stimulants to learn better and faster. However, the sources of stimulants are not always legal, and their impact had not been studied completely, especially in a long-term perspective.
All modern stimulants share one paramount issue: they appeared only recently, so the effect of long-term drug intake is not fully understood. However, people interested in immediate effects such as poker players, top managers, or students receive what exactly they want. For example, AMPH is a rather strong stimulant, working through an increase in the production of dopamine, norepinephrine, and serotonin by blocking their re-engagement. Its advantages may be formulated as the enhancement of the short-term memory, increased mobility, and overall stimulation. Among disadvantages, one may enumerate disorders in the functioning of neurotransmitters, impaired circulation, as well as the desire to increase dosage and dependence.
The experts from the pharmacological industry report that such drugs will clearly be in demand by the market. This is indicated by the enormous popularity of caffeine in modern society – it is an alkaloid with narcotic properties, with a similar but only weak effect on the brain, which slightly improves concentration and memory. Despite the weak impact and unpleasant side effects, many people are ready to take this substance in huge quantities throughout the day. The market for such substances is still quite small, they are mainly created for the treatment of memory disorders in the elderly, especially in neurodegenerative diseases, but some of them may be used in the future as cognitive stimulants. At least, in recent years, there has been an active discussion about the use of such drugs by healthy people.
For example, people with ADHD who have problems with concentration and attention-keeping can hardly focus on one subject. Because of this, if they suffer from an average or severe form of the disease, they are often prescribed stimulants, and mild ADHD can be treated with psychotherapy, such as cognitive behavior therapy or narrower types of psychotherapy designed specifically for ADHD. When it comes to medium or severe forms of the disease, pharmacological treatment is often used, for example, methylphenidate (Ritalin), which affects dopamine and norepinephrine in the brain. Adderal and other options may also be used, depending on a certain patient and his or her peculiarities regarding health condition and needs.
From the 1950s till today, there is a boom in the attempts of students to improve their ability to memorize large amounts of information while preparing for exams by means of stimulants. Now, the softer versions of these drugs such as Ritalin, for example, are used at the US universities. It became clear that they have side effects. The students take stimulants to increase their intellectual potential despite the fact that the substances they contain have never been tested by researchers for similar purposes. Some scientists and bioethics experts are considering the prospect of expanding the use of such drugs by healthy people who do not suffer from dementia. Can substances that affect key mechanisms of brain function remain as safe and effective as coffee and tea?
First, they do not specifically affect the memory, but, rather, the associated processes. Since they are psychotropic and not mnemotropic, they affect the processes associated with perception, attention, concentration, and so on. Second, amphetamines and other stimulants may cause addiction – the earlier age it happens, the more dangerous it can turn out to be. Now, the discussed stimulants are being created that can act on signals that are already transmitted inside the nerve cell. Some of these cascades that were discovered, they are patented. They are looking for drugs that can selectively modulate these memory properties, without affecting the psychotropic component.
Summary and Conclusions
The literature review based on the recent evidence published from 2005 till present reveal that the there are two opinions regarding the role of amphetamines and other stimulants on different memory types. Even though various studies pinpoint the positive impact of amphetamine on short-term and working memory, there are articles that provide the opposite findings. For example, one of them proves that the intake of amphetamine may increase the capacity to learn new activities and remember them within several days.
At the same time, the literature review also includes the studies that found significant concerns regarding the long-term impact of Adderal and other similar medications since students of many colleges prefer them as the way to activate their learning potential. With this in mind, it is possible to state that the mentioned impact had not been properly examined. The evidence shows the rapid increase in the consumption of stimulants by children with ADHD. Its positive impact is illustrated in several articles, and the effects involve more balanced behaviors, less hyperactivity, and higher concentration.
To conclude, the key implications of the presented literature review are the identified effects of various stimulants on short-term, long-term, and working memory. While amphetamine seems to be the most effective and legally used stimulant, others such as cocaine, cannabis, and methamphetamine seem to have more disadvantages compared to advantages. It is essential to emphasize the fact that further studies are needed to understand the given problem in an in-depth manner and collect more evidence regarding the long-term impact of stimulants on a person’s memory.
Appendices (Figures and Tables)
References
Ballard, M. E., Gallo, D. A., & de Wit, H. (2014). Amphetamine increases errors during episodic memory retrieval. Journal of Clinical Psychopharmacology, 34(1), 85-92. Web.
Berman, S. M., Kuczenski, R., McCracken, J. T., & London, E. D. (2009). Potential adverse effects of amphetamine treatment on brain and behavior: A review. Molecular Psychiatry, 14(2), 123-142. Web.
Calipari, E. S., & Ferris, M. J. (2013). Amphetamine mechanisms and actions at the dopamine terminal revisited. Journal of Neuroscience, 33(21), 8923-8925. Web.
Ciccarone, D. (2011). Stimulant abuse: Pharmacology, cocaine, methamphetamine, treatment, attempts at pharmacotherapy. Primary Care: Clinics in Office Practice, 38(1), 41-58. Web.
Dougherty, D. M., Mathias, C. W., Dawes, M. A., Furr, R. M., Charles, N. E., Liguori, A.,… Acheson, A. (2013). Impulsivity, attention, memory, and decision-making among adolescent marijuana users. Psychopharmacology, 226(2), 307-319. Web.
Hodzhev, Y., Yordanova, J., Diruf, M., Kratz, O., Moll, G. H., Kolev, V., & Heinrich, H. (2012). Methylphenidate (MPH) promotes visual cortical activation in healthy adults in a cued visuomotor task. Journal of Neural Transmission, 119(11), 1455-1464. Web.
Huang, Y. S., & Tsai, M. H. (2011). Long-term outcomes with medications for attention-deficit hyperactivity disorder. CNS Drugs, 25(7), 539-554. Web.
Kelley, J. B., Anderson, K. L., & Itzhak, Y. (2007). Long-term memory of cocaine-associated context: Disruption and reinstatement. Neuroreport, 18(8), 777-780. Web.
Kennedy, C. D., Houmes, S. W., Wyrick, K. L., Kammerzell, S. M., Lukowiak, K., & Sorg, B. A. (2010). Methamphetamine enhances memory of operantly conditioned respiratory behavior in the snail Lymnaea stagnalis. Journal of Experimental Biology, 213(12), 2055-2065. Web.
Morgan, C. J., Schafer, G., Freeman, T. P., & Curran, H. V. (2010). Impact of cannabidiol on the acute memory and psychotomimetic effects of smoked cannabis: Naturalistic study. The British Journal of Psychiatry, 197(4), 285-290. Web.
Spencer, R. C., Devilbiss, D. M., & Berridge, C. W. (2015). The cognition-enhancing effects of psychostimulants involve direct action in the prefrontal cortex. Biological Psychiatry, 77(11), 940-950. Web.
Tamm, L., Epstein, J. N., Lisdahl, K. M., Molina, B., Tapert, S., Hinshaw, S. P.,… Swanson, J. M. (2013). Impact of ADHD and cannabis use on executive functioning in young adults. Drug & Alcohol Dependence, 133(2), 607-614. Web.
Wang, W., Darvas, M., Storey, G. P., Bamford, I. J., Gibbs, J. T., Palmiter, R. D., & Bamford, N. S. (2013). Acetylcholine encodes long-lasting presynaptic plasticity at glutamatergic synapses in the dorsal striatum after repeated amphetamine exposure. Journal of Neuroscience, 33(25), 10405-10426. Web.
Wood, S., Sage, J. R., Shuman, T., & Anagnostaras, S. G. (2014). Psychostimulants and cognition: A continuum of behavioral and cognitive activation. Pharmacological Reviews, 66(1), 193-221. Web.
Young, E. J., Aceti, M., Griggs, E. M., Fuchs, R. A., Zigmond, Z., Rumbaugh, G., & Miller, C. A. (2014). Selective, retrieval-independent disruption of methamphetamine-associated memory by actin depolymerization. Biological Psychiatry, 75(2), 96-104. Web.
Zhou, Z., Enoch, M. A., & Goldman, D. (2014). Gene expression in the addicted brain. International Review of Neurobiology, 116(2), pp. 251-273. Web.