For a significant part of the past decades, extensive research has been conducted to investigate the biological factors contributing to addictions, and a vast section of that research has been directed towards drugs and substance abuse. The findings arising from such research is vital because it helps professionals and other relevant people to come up with strategies to deal with addictions, especially in relation to prevention and treatment. Although robust strategies have been put in place to address the problem of addiction, excessive consumption of alcohol and other drugs still exist and according to Saah (2005), the use and addiction to these substances in the United States costs the government more than $400 billion each year. Addictions are spread around the world and low-income or those nations, considered as “developing” could lack the required means to address addiction conditions. The effects of addictions are prevalent, and according to Saah (2005), for each individual identified as being addicted to drug and substance use, about seven people are affected. Therefore, such awakening statistics show the importance of understanding addiction, and how treatment and prevention strategies can be developed.
Nevertheless, addiction to drugs and substance abuse has always been perceived to be a personal choice. Many people in most communities around the world are quick to condemn drug addicts, and such perceptions often lead people to view drug addicts are social misfits. Although developed countries are developing knowledge and consequently, strategies to tackle the problem of addiction, poor countries and communities with low incomes do not view addiction as an issue to be prioritized. The main objective of this essay is to present the biological aspect of addiction, which far from many perspectives embraced by different communities, suggests that body processes, especially those taking place in people’s brains contribute greatly to addiction.
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Background
Institute of Medicine (2020) states that scientists began to seriously study addictive behaviors in the 1930s, and during that time, a vast section of members of the society thought individuals addicted to drugs had moral flaws, and consequently lacked willpower. Therefore, such perceptions influenced the way in which the society reacted to drug abuse, subsequently perceiving addiction as a moral shortcoming as opposed to treating it like a health problem. Such treatment contributed to the stress on castigation and not prevention or treatment. However, even way before scientists began to study about addiction, causes and consequences, societies in as far back as 1700 had their own perceptions about addiction. The society treated addiction as a criminal offense, and in some cases, the society tried to treat the victims with prayers, but in most cases, the victims would be admitted into mental institutions (Institute of Medicine, 2020). By admitting people into mental institutions, the society believed that drug addicts were not different from people suffering from psychological issues, especially those who were considered largely as “insane”.
Drug abuse was rampant in the U.S in the 1800s, especially with the introduction of heroin, cocaine, and morphine, which were used as curative properties. Although illicit drugs were suppressed globally by the beginning of the 20 th century, other drugs and substances such as amphetamines, hallucinogens, and marijuana were used extensively by the 1960s (Saah, 2005). Regarding the treatment options available during the 20 th century, a lot of emphasis was placed on spiritual methods. For example, in 1906 the practice of lay therapy was introduced in the Emmanuel Clinic in Boston to treat alcoholism (Institute of Medicine, 2020). The lay individuals applied psychological and spiritual approaches in treating addiction. An organization called Alcoholics Anonymous (AA) would later be formed in 1935 that also used spiritual approaches and welcomed those who recovered to get support. Within the same year, the very first narcotics farm was launched and operated as a rehab, prison, and research center.
Presently, numerous addiction treatment programs have been established globally, and particularly in developed countries. Perhaps the rise and spread of these programs can be attributed to an increase in knowledge about causes of drug and substance abuse, as well as the consequences. While people in the past thought addiction was caused by lack of willpower, modern scientists, researchers, and professionals are of the view that addiction is caused by many factors. The current treatment programs range from traditional, experimental practices, to evidence based and holistic services. Most of the recovery groups are peer based and supportive, and clearly mirror some of the treatment strategies used in the middle of the 20 th century. To a large extent, the use of peer to peer strategies and support shows that most professionals have the view that for addicts to recover, they need to be diverted away from the drugs causing the addiction. Therefore, the support groups and recovery centers try to keep the victims away and come up with activities that can help them focus elsewhere.
With the current treatment strategies for addiction, it can easily be believed that addiction is solely a consequence of association or environment; that for the victims to recover, they need to change their environment and embrace new habits in their lives. However, such a perception is misleading because addiction can be caused by biological or bodily processes, which can make it difficult for individuals to stop depending on some drugs and substances. Although some individuals may be willing to abandon some drugs, some biological processes may automatically trigger the urge to use them, and this is commonly witnessed in some people who despite being discharged from recovery centers, still cannot abandon using drugs. Therefore, addiction can be caused by biological mechanisms, and this means a different strategy needs to be developed to help address the addiction problem in individuals who are affected.
Understanding Neurobiology of Addiction
In the first place, neurobiology refers to the study of the makeup and association of neurons into working units, and this study avails a framework for comprehension of the circuits that leads to addiction. According to MacNicol (2017), two types of brain circuits exist, namely: diverse system and a point to point system. Regarding the point to point system, one neuron creates a single connection to another neuron, and this system conventionally uses amino acids such as glycine, Y-aminobutyric acid (GABA), glutamate, and aspartate. The amino acids are transmitters and in combination, this system is associated with the distinct actions (like movement) and responsiveness. On the other hand, the diverse system utilizes small molecule transmitters, such as, dopamine, serotonin and acetylcholine, and the function of this diverse system is to control or direct neural responses according to homeostatic needs. Nestlear (n.d) states that substances of abuse imitate the responses and mechanisms of a number of these neurotransmitters.
The Brain Reward System
According to MacNicol (2017), the brain reward system or circuit comprises of the mesolimbic dopamine structure (nucleus accumbens (NAC), basolateral amygdala, ventral tegmental area (VTA), prefrontal cortex), medial forebrain bundle, and lateral hippocampus. In essence, the brain reward system is a circuit that works to control a person’s response to agents that promote survival. Specifically, the system rewards tasks that contribute to survival such as social interaction, food, and sex by giving rise to a pleasurable feeling (MacNicol, 2017). The circuit also activates hippocampal memory that recalls the tasks, experiences and environment which caused the reward in order to stimulate similar behavior in the future. Such actions are basically facilitated by dopamine, and subsequently, increased activity causes the feeling of pleasure linked with rewarding behavior while reduced activity leading to reward-seeking behavior.
Glutamate and serotonin have regulation functions in the reward circuit system. Serotonergic neurons form in the dorsal raphe nucleus, which is a region associated with integration of stress and coping. The serotonergic neurons then move to the VTA and NAC, and subsequently regulate the secretion of dopamine in the reward circuit. According to Potenza (2013), neuroimaging results have showed the reward system is the primary focus of anomaly in the behaviors that cause craving, substance abuse, and active intoxication that form during the period of abstinence. For instance, functional magnetic resonance showed NAC activity increases at the phase of planning to use cocaine, but slowed down during the real intoxication (Potenza, 2013). Other MRI studies subsequently showed heightened action of amygdala, prefrontal cortex, as well as other regions of the reward circuit during intoxication and contemplation, and on the other hand, decreased activity during the period of withdrawal.
MacNicol (2017) also points out an animal experiment, where electrodes were inserted into the brain reward centers in an attempt to demonstrate the functioning of the mesolimbic reward system. In this study, the electrodes were configured to give stimulation to respond to numerous actions, like pressing a bar. The animals used in this study pressed the bar repetitively, and ignored that stimuli comprising of drink, food, and mating chances, to the extent of even dying of hunger. Volkow (2010) posits that drugs also stimulate the reward circuit strongly, and appear to affect the reward system in a way comparable to the electrodes in the animal experiments. The stimulation of the reward system by substances of abuse makes the individual to ignore all other things within the immediate environment, and to consequently, crave only for this single stimuli.
Effects of Drugs in the Reward System
Drugs stimulate the brain reward system by through an effect of dopamine, and subsequently prompt a phase of reduced dopamine action within the period of withdrawal. According to MacNicol (2017) when dopamine binds to the D1 receptor, it triggers a cAMP reaction element-binding protein, which causes heightened transcription of a variety of genes, including dynorphin and C-FosB that act to stop response of dopamine and to inhibit the reward system temporarily. Van Bockstaele (2012) points out that chronic or prolonged and extensive substance use causes sustained overpowering of the reward system such that more drug use is needed to give the same feeling of pleasure. Therefore, chronic substance abuse leads to reduced density of dopamine receptor, as well as metabolism in the reward circuit. Potenza (2013) notes that the down-regulation of this receptor is perceived to be a natural response to hyperstimulation of the reward circuit and leads to reduced ability of low-salience stimuli to trigger the sensitivity of the reward circuit. Additionally, the prolonged suppression of the reward system causes a general sense of depression and loss of interest in activities enjoyed previously. In the end, the use of drugs turns out to be the only activity that can stimulate the reward circuit in a strong way, which is sufficient to get the addict out of anhedonia state.
According to MacNicol (2017), ΔFosB is a gene transcription factor, which increases steadily with every use of a drug. This gene transcription factor is highly stable and exists for long durations after activation of the reward circuit. MacNicol (2017) states that ΔFosB has the result of stepping up the responsiveness of the reward system to the actions of a drug and is perceived to be one of the processes that cause feelings of euphoria and craving during the feelings that cause the actual use of a drug. Additionally, the changes in the structure of NAC as a consequence of ΔFosB are also perceived to be behind drug relapse. The overexpression of ΔFosB is known to happen in D1 neurons of the NAC of alcoholics and addicts. On the same note, there is a high possibility that this process can explain the feelings experienced by previous addicts when they are exposed to drugs again, where an exposure to an intoxicating substance just once can activate intensifying relapse rapidly. Van Bockstaele (2012) notes that repeated contact with drugs can step up the release of glutamate by prefrontal cortex and hippocampal neurons, which leads to a rise in sensitivity of the reward system to environmental cues and memories linked with past substance use. This process is perceived to be a vital aspect in the behaviors related to addiction and relapse.
Depression and anxiety seem to be intricately linked with addiction, and they always seem to present a dilemma in terms of treatment, especially in establishing the one that came first. Depression is usually stated to be a predictor of addiction and drug use, and there is about 60% prevalence of depression in chronic drug users (Volkow, 2010). The state of anhedonia, as well as irritability which is linked to addiction is often misguided for depression, and most of the time, addicts state that they take drugs to alleviate depressive symptoms. According to Van Bockstaele (2012), decreased serotonergic activity is presumed to be the cause of anxiety and depression. Perhaps it is the reason for the use of serotonin inhibitors currently to be the best treatment for depression. Besides, major depression is linked with decreased reward circuit stimulation as a consequence of serotonergic regulation of dopamine activity. Such response is perceived to be among the processes of reduced capacity to register pleasure with the onset of depression. People with depression discover that strong reward circuit stimulation caused by drug use give some temporary alleviation of depressive symptoms. However, drug use for prolonged periods overwhelms the reward system further, resulting into multiple symptoms of depression.
Stress is often an activator of drug use and relapse, even in times of lengthy phases of restraint. Volkow (2010) postulates that chronic stress and chronic substance abuse cause a rise in the levels of cerebrospinal fluid of corticotropin-releasing factor (CRF), which is an important element in reaction to stress. Basically, it is secreted by the hypothalamus and thalamus and acts to trigger the release of adrenocorticotropic hormone through the anterior pituitary. CRF also regulates endogenous stress and behavioral coping passageways in the dorsal raphe nucleus and amygdala, which are vital centers for registering memories of previous reward and environmental cues, mood, and state of activation. Chronic stress-associated stimulation of these centers is perceived to underlie the imbalanced emotional state linked with addiction to drugs. Just the same way CRF is an essential factor in depressive disorders and chronic anxiety; it may also contribute to some of the aversive aspects related to drug withdrawal.
Genetics of Addiction
Sometimes addiction and alcoholism has seemed to run across families and generations. Such an observation has always brought about the question whether addiction is a consequence of the environment or genetic factors. Nevertheless, it eventually appears that both factors contribute to addiction, and that previously, most of the literature mainly focused on environmental factors. According to MacNicol (2017), for individuals with siblings who are affected by addiction, their own risk of addiction is approximately 20-30% in women and 40-80% in men compared to 10-15% in the general population. Additionally, genetic research comprising twin and adoption studies reveals that about 50% of this heritable risk can be linked to genetics, while 50% can be attributed to environmental factors.
Nestlear (n.d) states that individuals who are susceptible to genetic influences are those with polymorphisms in the dopamine transporter, dopamine receptor, GABA receptor, serotonin receptor, catechol-O-methyltransferase enzyme, orexin receptor genes, and oxytocin receptor, among numerous other genetic polymorphisms. Additionally, Nestlear (n.d) states that gene clusters CHRNA 5 , CHRNA 3 and CHRNAB 4 are linked with high risk of dependence on nicotine. Additionally, differences in the consumption of opioid have been demonstrated to take place in connection with genetic variants of the OPRM1 mu opioid receptor (MacNicol, 2017). On the same note, MacNicol (2017) presents the theory of epigenetics, which suggests that the expression of genes is altered by environmental influences via three main processes: Histone acetylation, DNA methylation, and non-coding RNA. The suggestion is that these alterations can be inherited even without changes in DNA structures. DNA methylation is perceived to be very vital in cellular imprinting and differentiation. Non-coding RNAs change the interaction of DNA with transcription factors. On the other hand, histones are composed of proteins, and they regulate DNA packing, and in this case, they expose the unpacked DNA to transcription factors, hence more easily transcribed. Nestlear (n.d) points out that epigenetic alteration can be inherited between generations due to alterations in the germ cell lines, and could possibly symbolize a connection between the genetic, environmental and future traits in people, as well as their descendants. However, epigenetics is a relatively new field of study, which is also complex in nature and with new research and discoveries, more information, is bound to be discovered that could revolutionize the understanding of the connection among the various aspects discussed.
Adolescent Addiction Susceptibility
Some motivation-focused models that attempt to explain the biology of addiction propose that some regions of the brain are involved extensively in contributing to addiction vulnerability and motivated behaviors. For example, one of the models illuminating on adolescent susceptibility to addiction divided primary and secondary motivational neurocircuitry (Potenza, 2013). To begin with the primary circuitry, it comprises of the striatum, thalamus, and the prefrontal cortex. Parallel loops comprising these parts have been suggested to be the basic causes of behaviors and motivations, inclusive of those in addictions. Additionally, the limbic loops that include more ventral areas of striatum and cortex have been suggested to be specifically relevant to new or impulsive behaviors. On the other hand, those loops which include more dorsal areas of striatum and cortex have been suggested to be relevant to compulsive or habitual behaviors. This model is applicable to both substance and non-substance addictions, even including behaviors associated with obesity and excessive food intake.
Another motivational neurocircuitry has been put forward to expound on how brain circuits could affect motivational decision-making mechanisms and behaviors in the primary circuitry. In particular, a variety of factors could affect the decisions to use drugs or get engaged in addictive behaviors. According to Potenza (2013), an integration of external and internal factors may lead to adolescents’ induction and continued involvement in addictive behaviors. For instance, an individual’s emotional state, and specifically, feelings of stress or being upset may cause the individual to use drugs. Subsequently, areas in the brain which are associated with emotional processing, such as the anterior cingulate and medial prefrontal cortices, and the amygdala may give crucial information into primary motivational circuitry and lead to decisions to engage in drug use in emotional reactive “hot” conditions compared to reflective, “cold” conditions.
Potenza (2013) states that the immaturity of adolescents in brain areas such as the prefrontal cortex involved in motivational and emotional processing could make adolescents to be biologically vulnerable to participation in addictive behaviors. Additionally, Potenza (2013) postulates that adolescents portray mainly limbic/subcortical reactions to individualized stress cues, and favorite food cues while adults present both limbic/subcortical and prefrontal cortical reactions. In models illuminating on adolescent addiction susceptibility, the function of brain areas to other states associated with motivational compulsions and behaviors has been cited as vital. For instance, brain areas like the septum and the hypothalamus, which are involved in the homeostatic mechanisms, could contribute significantly.
Individual relevant experiences may also trigger motivations and decisions to engage in drug use. Besides, in the event of relatively smaller influences of prefrontal cortically facilitated self-control in adolescence, such recollections may play a significant role in the decision-making process of adolescents in relation to addictive behaviors. Areas in the brain like the temporal cortices or the hippocampus, which have been associated with storing and perception of memories, especially the emotional ones, associated with drug use in the past, may therefore give vital contextual memory influences. Other brain areas like the insula and parietal cortex could also get involved by triggering decisions and motivations to participate in addictive behaviors. Therefore, the emotional instability of adolescents and its impact on how attention is directed could contribute extensively to adolescent engagement in substance use or other behaviors that have the potential of causing addiction. The most important point in this section is that young people or rather, adolescents are susceptible to addictions because of the immature state of the brains, especially in relation to those regions that deal with emotions. Therefore, adolescents may not have superior coping mechanisms that can help them deal with the various emotional states, and that potentially causes to resort to the abuse of drugs if they are available.
Discussion
It is evident that various functions of the body and processes contribute to addiction. Most of these processes happen in the brain, especially in a region commonly referred to as the brain reward system. The most crucial aspect of this system is that it triggers the hippocampal memory to remember tasks, experiences as well as the environment that led to a particular reward that stimulates pleasurable feelings. The brain reward circuit in essence rewards activities that lead to survival such as food, sex, and social interaction. The activities or functions of these processes in the brain are essentially influenced by dopamine, whereby increased activity results to pleasurable feelings which are associated with rewarding behavior while decreased activity leads to reward-seeking behavior.
Addiction in its literal definition is that craving and consequently, the habit of engaging in various activities, and in the case of this essay, addiction is defined in the context or drug and substance abuse. People who are addicted to drugs usually feel the urge to engage in them, and when they engage in drug use, they experience pleasurable feelings, and when they stay without taking drugs, they will definitely try to get these drugs, in what is referred to as “reward-seeking behavior”. With this in mind, then the argument that comes forward is that addiction, especially to drugs, is a consequence of biological mechanisms, and on that note, these mechanisms can be beyond the control of individuals. For a long time, people had the notion that addiction is the consequence of carelessness; that drug addicts do not have the willpower to stop taking drugs. On the contrary, the biological processes, especially taking place in the brain reward circuit may take hostage of addicts; people may be entangled in a chain that despite their willingness to abandon the addiction, find that the biological processes are too strong. Addicts need to ensure that they keep on taking the drugs to be ‘rewarded’ and to achieve pleasurable feelings or they will feel a sense of misery and hopelessness.
On the same note, addiction and mental conditions such as depression and anxiety seem to be intricately linked. Individuals who are usually taken to rehabilitation centers in an attempt to abandon drug use usually find it very difficult to cope. For the initial stages of the rehabilitation process, the individuals may experience hallucinations, episodes of depression and anxiety. Similarly, drug addicts trying to abandon the habit may turn psychotic, a situation where they engage in violent and erratic behavior. A significant number of individuals leaving rehabilitation centers still go back to drug taking because the hippocampal memory is triggered by the brain reward circuit to recall the pleasurable feelings that were associated with certain environments, tasks and experiences. It also seems that social interaction only contributes a small portion of addiction. If indeed the social environment was to contribute significantly to addiction, then the remedy would have been simply to move the addicts from one environment to another. However, such treatment strategies have not been particularly effective because biological mechanisms and processes are usually too strong such that individuals appear sickly when transferred from one environment to another.
Another important thing is that adolescents are highly susceptible to addiction because of the relatively immature state of the functioning of their brain, especially that part which deals with emotions. Consequently, adolescents are likely to make irrational decisions, especially if certain experiences, tasks, and environments trigger pleasurable feelings in their brain reward circuit. For example, if an adolescent gets pleasurable feelings from drinking alcohol once, the urge to drink again will be so strong and irresistible compared to adults. And in this case also, adolescents will not make rational decisions that can guide their drinking habits. Adults could at least think about drinking, and can consequently control what they drink, how they do it and why they do so.
From the biological basis of addiction, various implications can be gathered. Firstly, young people are likely to develop addiction compared to adults. For policy-makers, it is important to control exposure of adolescents to drugs and other substances that they could be potentially harmful. For instance, in many countries around the world, there are age restrictions on drinking of alcohol, and to be specific, people below the age of eighteen years are not allowed to drink alcohol. The rationale is that once young people start drinking alcohol, they could easily develop addictions, drink irresponsibly, and ruin their lives. Therefore, it is important that young people, especially adolescents and young adults are either restricted from engaging in drug taking or are educated to regulate the consumption of drugs and other substances.
Another important implication regards the treatment of addicts. For a long time, most interventions have leaned towards taking individuals away from various drugs and substances that cause their addiction and trying to make them focus on new “positive” habits. However, since addiction is a consequence of various body functions and processes taking place in the brain, it is important to come up with medications that can regulate these processes. The brain reward circuit needs to be regulated by agents that stop various pleasurable feelings and reward-seeking behaviors. It is not very easy for addicts to immediately abandon their habits by simply redirecting their focus. The best thing would be to integrate the various intervention strategies. For instance, as addicts take the various drugs to regulate their brain functions, they should also participate in various activities routinely.
Summary
Various points can be gathered from this essay. The first and most crucial point is that biological functions can indeed contribute greatly to addiction. People usually get pleasurable feelings and sense of satisfaction by using various drugs, and these feelings occur in the brain. In particular, the registration of these feelings is associated with a region in the brain, which is referred to as the brain reward circuit. This system triggers the hippocampal memory to recall environments, tasks and experiences that caused certain pleasurable feelings, and this makes individuals who are addicted to drugs to always strive and experience these prior events once again. Therefore, addiction is mainly as a consequence of these processes occurring in the brain. Closely related to these biological processes are genetic changes which may happen in individuals as a consequence of using various drugs and substances. These genetic alterations may be passed from one generation to another, and hence, they can cause certain family clusters to be highly vulnerable to addiction. Quite importantly, adolescents, and young adults could be quite susceptible to addiction because of the relatively less developed state of their brains, and that could affect how they deal with emotions and make decisions. The biggest implication therefore comes in the aspect of treatment, where professionals need to research and develop an integrated method of treating addiction. Treatment should involve both use of medication that regulates the various processes as well as therapeutic methods, which are designed to influence the behavior of the addicts.
References
Institute of Medicine. (2020). Pathways of addiction: Opportunities in drug abuse research. https://www.ncbi.nlm.nih.gov/books/NBK232965/
MacNicol, B. (2017). The biology of addiction. Canadian Journal of Anesthesia/Journal canadien d'anesthésie , 64 (2), 141-148.
Nestlear, E.J. (n.d). Molecular Mechanisms of Addiction. https://www.bbrfoundation.org/sites/default/files/pdfs/oct-2013-webinar-slides.pdf
Potenza, M. N. (2013). Biological contributions to addictions in adolescents and adults: Prevention, treatment, and policy implications. Journal of Adolescent Health , 52 (2), S22-S32.
Saah, T. (2005). The evolutionary origins and significance of drug addiction. Harm reduction journal , 2 (1), 1-7.
Van Bockstaele, E. J. (2012). The Neurobiology of Addictive-Like Behaviors. ILAR journal/National Research Council, Institute of Laboratory Animal Resources , 53 (1), 1.
Volkow, N. D. (2010). Drugs, brains, and behavior: The science of addiction. Retrieved on May , 16 , 2020. https://www.drugabuse.gov/sites/default/files/soa_2014.pdf
