Addiction Problems Essay

When people face some troubles, problems, and challenges, they look for ways to solve them. Unfortunately some people start taking drugs. This essay we would like to dedicate to drug abuse and drug addiction problem. We believe that drug addiction essay should turn public attention to this urgent issue.

Drug addiction is a disease that characterizes by a pathological inclination to use drugs. The problem of drug abuse exists for a long time and it is very hard to fight it. Only few people manage to overcome it.

Causes of drug addiction

There are certain reasons that can cause the disease.

  • The main reason is dissatisfaction with life; it means that there is lack of something in a person’s life. This problem can appear even in the early childhood. A person always looks for something that can give him new feelings and experience. And in most cases drugs give what human desire.
  • Another very common reason is upbringing. A child, who is brought up in a family of drug addicts or in a dysfunctional family, or incomplete family, is prone to become drug addicted person in the future. An emotional connection with the parents and their attention are very important for a child. When a child does not get it, he or she is exposed to emotional breakdowns. If a person didn’t get enough attention, he may become addicted and not only drug addicted.

Drug addiction is a disease and it is classified into 2 forms: physical and psychological addiction.

Psychological drug addiction

Psychological dependence is characterized by a painful desire to experience pleasant feelings that drugs provoke. Some people try to get rid of discomfort with the help of drugs. This kind of addiction will definitely appear if a drug is used for a couple of times. Some individuals are exposed to such an addiction right after the first use of narcotic substance. Psychological dependence occurs due to the fact that a person wants to change his condition and the feeling with the help of drugs. It is really a terrible disease. In this case a person does not leave the thought about the drug. There is a depression, bad mood. When a person gets a dose of a drug his condition changes. He becomes excited and cheerful. It happens that one can not resist his desire to get the drug. So he does everything possible to get it. Such a condition is regarded as a strong psychological dependence.

Physical drug addiction

It should be mentioned that physical dependence is much more stronger than psychological. All the body suffers in this state. When a person abuses drugs constantly the body gets used to it and it changes in such a way that it should always get drugs. Physical dependence manifests itself through somatic and mental disorders in the body. He always wants to get the drug, and almost always is in a state of narcotic intoxication.

During the period when the drug is absent, an individual feels depressed, there are sleep problems and disruptions in all body systems. These symptoms disappear only when the body gets the drug. During various types of drug addiction, withdrawal syndrome manifests itself in different ways, it means there are different symptoms. However, it should be mentioned that not all types of drugs cause physical dependence. Opiates, cannabis and ephedrine derivatives, cause strong drug addiction. In medicine, there is such a term as drugs tolerance. This means that each time the addict requires bigger dose of narcotic substances.

Symptoms of drug addiction

In fact it is very hard to recognize the beginner addict. Even experienced doctors sometimes can not do this. Sometimes a person looks very well, and you would never think that he has harmful passions. Characteristic features of the inveterate addict are the following:

  • Indifferent look
  • Expanded or constricted pupils, that is not caused by the lighting.
  • Such a person wears long-leaved clothes no matter what weather is.
  • Appearance is untidy – dry hair, swollen hands, black broken teeth.
  • Such a person will slouch.
  • Lethargy and do not quite understandable speech.
  • Lethargy and awkward movements.
  • When a person is asked, he irritates and responses in a raised voice.
  • You can find marks of injections on the hand rear side. Addicts do injections throughout the body. They even manage to inject harmful substances in the blood vessels of the head. Sometimes marks of injections merge in purple-blue hemorrhage.

How to identify drug addiction in adolescents

Very often teenagers suffer from drug addiction. All the parents should pay much attention to their children. If parents are attentive they can notice and suspect that something is wrong.

  • The child becomes quite secretive.
  • A child can leave the house at the time when earlier he was occupied with something.
  • Disturbed sleep.
  • Lose of interest to the studies, as well as hobbies that the child enjoyed before.
  • Very often, children begin to miss classes without explanation.
  • A child behaves strangely. His behaviour reminds alcoholic intoxication.
  • A child begins to demand more money. Often there is the loss of money from a purse or valuables from the house.
  • A child has new friends, who are not trustworthy.
  • There are often changes in mood.
  • And of course there can be noticed injection marks on the hands.

Drug influence on the body

You should always remember that influence of the drugs on the body is extremely harmful.

  • Cardiovascular system and heart suffer from drug.
  • There is a steady decline in blood pressure.
  • Pulse is also weak.
  • Consequently, the body begins to suffer from lack of oxygen, hypoxia condition develops. Due to lack of oxygen there are the metabolism and organs nutrition disorders.
  • Heart functioning declines and eventually heart wears out.
  • Often pneumonia adds.
  • If a person suffered this disease after a while there is a risk of heart failure symptoms, and as a consequence – death.
  • Drug substances influence also digestive system. Due to the use of drugs, an appetite may decrease. Typically, addicts do not eat fully or even refuse to eat. Furthermore, digestion becomes difficult. There are often stomach aches.
  • Human liver suffers a lot, cause it removes toxic substances from the body. That is why there is a high risk of getting such a disease as cirrhosis of the liver among the addicts.
  • Prolonged use of the drug leads to the fact that a man loses sexual interest in the opposite sex. Men who abuse drugs often suffer from impotence. Some types of drugs can affect the genetics. For example, LSD rearranges some rows of chromosomes, so if a person take this drug even once there is a high chance of diseased offspring birth.
  • If the drug is taken in the form of smoking, consequently lungs suffer: chronic bronchitis, pneumonia, lung cancer.

It should be mentioned that child and adolescent drug abuse is a terrible phenomenon. Kids and teenagers are very prone to get strong addiction, because their mind is not quite stable yet. Drug abuse by children can cause serious mental disorders, and dementia. Also moral destruction in children is much faster than in adults. The drugs affect adversely the physical development of the adolescent. These children are significantly behind their peers in height and weight.

Drug addiction is a very horrible disease. Very few, who have a strong will and are able to quit taking drugs, manage to overcome it. So before trying something new in your life, think about the consequences.

I think everyone should read essay on drugs, because this issue concerns every member of society. Unfortunately, drug addiction is not the only problem of our modern life. Previously we discussed cyber bullying problem. For more information visit our website. There you will find essays on urgent topics, essays about nature and its mysteries, and many others. You can also get help from our team of first-class writers. Join us, we are waiting for you!

"Addictive" redirects here. For other uses, see Addiction (disambiguation) and Addictive (disambiguation).

Addiction and dependence glossary[1][2][3][4]
  • addiction – a brain disorder characterized by compulsive engagement in rewarding stimuli despite adverse consequences
  • addictive behavior – a behavior that is both rewarding and reinforcing
  • addictive drug – a drug that is both rewarding and reinforcing
  • dependence – an adaptive state associated with a withdrawal syndrome upon cessation of repeated exposure to a stimulus (e.g., drug intake)
  • drug sensitization or reverse tolerance – the escalating effect of a drug resulting from repeated administration at a given dose
  • drug withdrawal – symptoms that occur upon cessation of repeated drug use
  • physical dependence – dependence that involves persistent physical–somatic withdrawal symptoms (e.g., fatigue and delirium tremens)
  • psychological dependence – dependence that involves emotional–motivational withdrawal symptoms (e.g., dysphoria and anhedonia)
  • reinforcing stimuli – stimuli that increase the probability of repeating behaviors paired with them
  • rewarding stimuli – stimuli that the brain interprets as intrinsically positive and desirable or as something to approach
  • sensitization – an amplified response to a stimulus resulting from repeated exposure to it
  • substance use disorder – a condition in which the use of substances leads to clinically and functionally significant impairment or distress
  • tolerance – the diminishing effect of a drug resulting from repeated administration at a given dose

Addiction is a brain disorder characterized by compulsive engagement in rewarding stimuli despite adverse consequences.[8] Despite the involvement of a number of psychosocial factors, a biological process – one which is induced by repeated exposure to an addictive stimulus – is the core pathology that drives the development and maintenance of an addiction.[1][9] The two properties that characterize all addictive stimuli are that they are reinforcing (i.e., they increase the likelihood that a person will seek repeated exposure to them) and intrinsically rewarding (i.e., they are perceived as being inherently positive, desirable, and pleasurable).[1][3][7]

Addiction is a disorder of the brain's reward system which arises through transcriptional and epigenetic mechanisms and occurs over time from chronically high levels of exposure to an addictive stimulus (e.g., eating food, the use of cocaine, engagement in sexual intercourse, participation in high-thrill cultural activities such as gambling, etc.).[1][10][11]ΔFosB, a gene transcription factor, is a critical component and common factor in the development of virtually all forms of behavioral and drug addictions.[10][11][12][13] Two decades of research into ΔFosB's role in addiction have demonstrated that addiction arises, and the associated compulsive behavior intensifies or attenuates, along with the overexpression of ΔFosB in the D1-typemedium spiny neurons of the nucleus accumbens.[1][10][11][12] Due to the causal relationship between ΔFosB expression and addictions, it is used preclinically as an addiction biomarker.[1][10][12] ΔFosB expression in these neurons directly and positively regulates drug self-administration and reward sensitization through positive reinforcement, while decreasing sensitivity to aversion.[note 1][1][10]

As described by two groups of researchers, addiction exacts an "astoundingly high financial and human toll" on individuals and society as a whole through the direct adverse effects of drugs, associated healthcare costs, long-term complications (e.g., lung cancer with smoking tobacco, liver cirrhosis with drinking alcohol, or meth mouth from intravenous methamphetamine), the functional consequences of altered neural plasticity in the brain, and the consequent loss of productivity.[14][15][16] Classic hallmarks of addiction include impaired control over substances or behavior, preoccupation with substance or behavior, and continued use despite consequences.[17] Habits and patterns associated with addiction are typically characterized by immediate gratification (short-term reward), coupled with delayed deleterious effects (long-term costs).[18]

Examples of drug and behavioral addictions include: alcoholism, amphetamine addiction, cocaine addiction, nicotine addiction, opiate addiction, food addiction, gambling addiction, and sexual addiction. The only behavioral addiction recognized by the DSM-5 and the ICD-10 is gambling addiction. The term addiction is misused frequently to refer to other compulsive behaviors or disorders, particularly dependence, in news media.[19] An important distinction between drug addiction and dependence is that drug dependence is a disorder in which cessation of drug use results in an unpleasant state of withdrawal, which can lead to further drug use.[20] Addiction is the compulsive use of a substance or performance of a behavior that is independent of withdrawal.

Neuropsychology[edit]

This section needs expansion. You can help by adding to it.(February 2016)

Cognitive control and stimulus control, which is associated with operant and classical conditioning, represent opposite processes (i.e., internal vs external or environmental, respectively) that compete over the control of an individual's elicited behaviors.[21] Cognitive control, and particularly inhibitory control over behavior, is impaired in both addiction and attention deficit hyperactivity disorder.[22][23] Stimulus-driven behavioral responses (i.e., stimulus control) that are associated with a particular rewarding stimulus tend to dominate one's behavior in an addiction.[23]

Stimulus control of behavior[edit]

See also: Stimulus control

Cognitive control of behavior[edit]

See also: Cognitive control

Behavioral addiction[edit]

Main article: Behavioral addiction

The term behavioral addiction correctly refers to a compulsion to engage in a natural reward – which is a behavior that is inherently rewarding (i.e., desirable or appealing) – despite adverse consequences.[6][11][13] Preclinical evidence has demonstrated that marked increases in the expression of ΔFosB through repetitive and excessive exposure to a natural reward induces the same behavioral effects and neuroplasticity as occurs in a drug addiction.[11][24][25][26]

Reviews of both clinical research in humans and preclinical studies involving ΔFosB have identified compulsive sexual activity – specifically, any form of sexual intercourse – as an addiction (i.e., sexual addiction).[11][24] Moreover, reward cross-sensitization between amphetamine and sexual activity, meaning that exposure to one increases the desire for both, has been shown to occur preclinically and clinically as a dopamine dysregulation syndrome;[11][24][25][26] ΔFosB expression is required for this cross-sensitization effect, which intensifies with the level of ΔFosB expression.[11][25][26]

Reviews of preclinical studies indicate that long-term frequent and excessive consumption of high fat or sugar foods can produce an addiction (food addiction).[11][13]

Gambling is a natural reward which is associated with compulsive behavior and for which clinical diagnostic manuals, namely the DSM-5, have identified diagnostic criteria for an "addiction".[11] There is evidence from functional neuroimaging that gambling activates the reward system and the mesolimbic pathway in particular.[11][27] Similarly, shopping and playing videogames are associated with compulsive behaviors in humans and have also been shown to activate the mesolimbic pathway and other parts of the reward system.[11] Based upon this evidence, gambling addiction, video game addiction and shopping addiction are classified accordingly.[11][27]

Risk factors[edit]

There are a range of genetic and environmental risk factors for developing an addiction that vary across the population.[1][28] Roughly half of an individual's risk for developing an addiction is derived from genetics, while the other half is derived from the environment.[1] However, even in individuals with a relatively low genetic loading, exposure to sufficiently high doses of an addictive drug for a long period of time (e.g., weeks–months) can result in an addiction.[1] In other words, anyone can become an addict under the right circumstances.

Genetic factors[edit]

It has long been established that genetic factors along with environmental (e.g., psychosocial) factors are significant contributors to addiction vulnerability. Epidemiological studies estimate that genetic factors account for 40–60% of the risk factors for alcoholism. Similar rates of heritability for other types of drug addiction have been indicated by other studies.[29] Knestler hypothesized in 1964 that a gene or group of genes might contribute to predisposition to addiction in several ways. For example, altered levels of a normal protein due to environmental factors could then change the structure or functioning of specific brain neurons during development. These altered brain neurons could change the susceptibility of an individual to an initial drug use experience. In support of this hypothesis, animal studies have shown that environmental factors such as stress can affect an animal's genotype.[29]

Overall, the data implicating specific genes in the development of drug addiction is mixed for most genes. One reason for this may be that the case is due to a focus of current research on common variants. Many addiction studies focus on common variants with an allele frequency of greater than 5% in the general population, however when associated with disease, these only confer a small amount of additional risk with an odds ratio of 1.1–1.3 percent. On the other hand, the rare variant hypothesis states that genes with low frequencies in the population (<1%) confer much greater additional risk in the development of disease.[30]

Genome-wide association studies (GWAS) are a recently developed research method which are used to examine genetic associations with dependence, addiction, and drug use. These studies employ an unbiased approach to finding genetic associations with specific phenotypes and give equal weight to all regions of DNA, including those with no ostensible relationship to drug metabolism or response. These studies rarely identify genes from proteins previously described via animal knockout models and candidate gene analysis. Instead, large percentages of genes involved in processes such as cell adhesion are commonly identified. This is not to say that previous findings, or the GWAS findings, are erroneous. The important effects of endophenotypes are typically not capable of being captured by these methods. Furthermore, genes identified in GWAS for drug addiction may be involved either in adjusting brain behavior prior to drug experiences, subsequent to them, or both. [31]

A study that highlights the significant role genetics play in addiction is the twin studies. Twins have similar and sometimes identical genetics. Analyzing these genes in relation to genetics has helped geneticists understand how much of a role genes play in addiction. Studies performed on twins found that rarely did only one twin have an addiction. In most cases where at least one twin suffered from an addiction, both did, and often to the same substance.[32]

Environmental factors[edit]

Environmental risk factors for addiction are the experiences of an individual during their lifetime that interact with the individual's genetic composition to increase or decrease the his or her vulnerability to addiction.[1] A number of different environmental factors have been implicated as risk factors for addiction, including various psychosocial stressors;[1] however, an individual's exposure to an addictive drug is by far the most significant environmental risk factor for addiction.[1] The National Institute on Drug Abuse cites lack of parental supervision, the prevalence of peer substance use, drug availability, and poverty as risk factors for substance use among children and adolescents.[33]

Adverse childhood experiences (ACEs) are various forms of maltreatment and household dysfunction experienced in childhood. The Adverse Childhood Experiences Study by the Centers for Disease Control and Prevention has shown a strong dose–response relationship between ACEs and numerous health, social, and behavioral problems throughout a person's lifespan, including those associated with substance abuse.[34] Children's neurological development can be permanently disrupted when they are chronically exposed to stressful events such as physical, emotional, or sexual abuse, physical or emotional neglect, witnessing violence in the household, or a parent being incarcerated or suffering from a mental illness. As a result, the child's cognitive functioning or ability to cope with negative or disruptive emotions may be impaired. Over time, the child may adopt substance use as a coping mechanism, particularly during adolescence.[34] A study of 900 court cases involving children who experienced abuse found that a vast amount of them went on to suffer from some form of addiction in their adolescence or adult life.[35] This pathway towards addiction that is opened through stressful experiences during childhood can be avoided by a change in environmental factors throughout an individuals life and opportunities of professional help.[35]

Age[edit]

Adolescence represents a period of unique vulnerability for developing addiction.[36] In adolescence, the incentive–rewards systems in the brain mature well before the cognitive control center. This consequentially grants the incentive–rewards systems a disproportionate amount of power in the behavioral decision making process. Therefore, adolescents are increasingly likely to act on their impulses and engage in risky, potentially addicting behavior before considering the consequences.[37] Not only are adolescents more likely to initiate and maintain drug use, but once addicted they are more resistant to treatment and more liable to relapse.[38][39] Statistics have shown that those who start to drink alcohol at a younger age are more likely to become dependent later on. About 33% of the population tasted their first alcohol between the ages of 15 and 17, while 18% experienced it prior to this. As for alcohol abuse or dependence, the numbers start off high with those who first drank before they were 12 and then drop off after that. For example, 16% of alcoholics began drinking prior to turning 12 years old, while only 9% first touched alcohol between 15 and 17. This percentage is even lower, at 2.6%, for those who first started the habit after they were 21.[40]

Most individuals are exposed to and use addictive drugs for the first time during their teenage years.[41] In the United States, there were just over 2.8 million new users of illicit drugs in 2013, or about 7,800 new users per day.[41] Over half (54.1 percent) were under 18 years of age.[41]

Comorbid disorders[edit]

Individuals with comorbid (i.e., co-occurring) mental health disorders such as depression, anxiety, attention-deficit/hyperactivity disorder (ADHD) or post-traumatic stress disorder are more likely to develop substance use disorders.[42][43][44] The National Institute on Drug Abuse cites early aggressive behavior as a risk factor for substance use.[33]

Transgenerational epigenetic factors[edit]

See also: Transgenerational epigenetic inheritance

Epigenetic genes and their products (e.g., proteins) are the key components through which environmental influences can affect the genes of an individual;[28] they also serve as the mechanism responsible for the transgenerational epigenetic inheritance of behavioral phenotypes, a phenomenon in which environmental influences on the genes of a parent can affect the associated traits and behavioral phenotypes of their offspring (e.g., behavioral responses to certain environmental stimuli).[28] In addiction, epigenetic mechanisms play a central role in the pathophysiology of the disease;[1] it has been noted that some of the alterations to the epigenome which arise through chronic exposure to addictive stimuli during an addiction can be transmitted across generations, in turn affecting the behavior of one's children (e.g., the child's behavioral responses to addictive drugs and natural rewards).[28][45] More research is needed to determine the specific epigenetic mechanisms and the nature of heritable behavioral phenotypes that arise from addictions in humans.[28][45] Based upon preclinical evidence with lab animals, the addiction-related behavioral phenotypes that are transmitted across generations may serve to increase or decrease the child's risk of developing an addiction.[28][45]

Mechanisms[edit]

Transcription factor glossary
  • gene expression – the process by which information from a gene is used in the synthesis of a functional gene product such as a protein
  • transcription – the process of making messenger RNA (mRNA) from a DNA template by RNA polymerase
  • transcription factor – a protein that binds to DNA and regulates gene expression by promoting or suppressing transcription
  • transcriptional regulationcontrolling the rate of gene transcription for example by helping or hindering RNA polymerase binding to DNA
  • upregulation, activation, or promotionincrease the rate of gene transcription
  • downregulation, repression, or suppressiondecrease the rate of gene transcription
  • coactivator – a protein that works with transcription factors to increase the rate of gene transcription
  • corepressor – a protein that works with transcription factors to decrease the rate of gene transcription
  • response element – a specific sequence of DNA that a transcription factor binds to

Signaling cascade in the nucleus accumbens that results in psychostimulant addiction
v·t·e

This diagram depicts the signaling events in the brain's reward center that are induced by chronic high-dose exposure to psychostimulants that increase the concentration of synaptic dopamine, like amphetamine, methamphetamine, and phenethylamine. Following presynaptic dopamine and glutamateco-release by such psychostimulants,[46][47]postsynaptic receptors for these neurotransmitters trigger internal signaling events through a cAMP-dependent pathway and a calcium-dependent pathway that ultimately result in increased CREB phosphorylation.[46][48][49] Phosphorylated CREB increases levels of ΔFosB, which in turn represses the c-Fos gene with the help of corepressors;[46][50][51]c-Fosrepression acts as a molecular switch that enables the accumulation of ΔFosB in the neuron.[52] A highly stable (phosphorylated) form of ΔFosB, one that persists in neurons for 1–2 months, slowly accumulates following repeated high-dose exposure to stimulants through this process.[50][51] ΔFosB functions as "one of the master control proteins" that produces addiction-related structural changes in the brain, and upon sufficient accumulation, with the help of its downstream targets (e.g., nuclear factor kappa B), it induces an addictive state.[50][51]

Chronic addictive drug use causes alterations in gene expression in the mesocorticolimbic projection.[13][53][54] The most important transcription factors that produce these alterations are ΔFosB, cAMP response element binding protein (CREB), and nuclear factor kappa B (NF-κB).[13] ΔFosB is the most significant biomolecular mechanism in addiction because the overexpression of ΔFosB in the D1-typemedium spiny neurons in the nucleus accumbens is necessary and sufficient for many of the neural adaptations and behavioral effects (e.g., expression-dependent increases in drug self-administration and reward sensitization) seen in drug addiction.[13] ΔFosB expression in nucleus accumbensD1-typemedium spiny neurons directly and positively regulates drug self-administration and reward sensitization through positive reinforcement while decreasing sensitivity to aversion.[note 1][1][10] Specific drug addictions in which ΔFosB has been implicated in addictions to alcohol, amphetamine, cannabinoids, cocaine, methylphenidate, nicotine, phenylcyclidine, propofol, opiates, and substituted amphetamines, among others.[10][13][53][55][56]ΔJunD, a transcription factor, and G9a, a histone methyltransferase, both oppose the function of ΔFosB and inhibit increases in its expression.[1][13][57] Increases in nucleus accumbens ΔJunD expression (via viral vector-mediated gene transfer) or G9a expression (via pharmacological means) reduces, or with a large increase can even block, many of the neural and behavioral alterations seen in chronic drug abuse (i.e., the alterations mediated by ΔFosB).[12][13]

ΔFosB also plays an important role in regulating behavioral responses to natural rewards, such as palatable food, sex, and exercise.[13][58] Natural rewards, like drugs of abuse, induce gene expression of ΔFosB in the nucleus accumbens, and chronic acquisition of these rewards can result in a similar pathological addictive state through ΔFosB overexpression.[11][13][58] Consequently, ΔFosB is the key transcription factor involved in addictions to natural rewards (i.e., behavioral addictions) as well;[13][11][58] in particular, ΔFosB in the nucleus accumbens is critical for the reinforcing effects of sexual reward.[58] Research on the interaction between natural and drug rewards suggests that dopaminergic psychostimulants (e.g., amphetamine) and sexual behavior act on similar biomolecular mechanisms to induce ΔFosB in the nucleus accumbens and possess bidirectional cross-sensitization effects that are mediated through ΔFosB.[11][25][26] This phenomenon is notable since, in humans, a dopamine dysregulation syndrome, characterized by drug-induced compulsive engagement in natural rewards (specifically, sexual activity, shopping, and gambling), has also been observed in some individuals taking dopaminergic medications.[11]

ΔFosB inhibitors (drugs or treatments that oppose its action) may be an effective treatment for addiction and addictive disorders.[59]

The release of dopamine in the nucleus accumbens plays a role in the reinforcing qualities of many forms of stimuli, including naturally reinforcing stimuli like palatable food and sex.[60][61] Altered dopamine neurotransmission is frequently observed following the development of an addictive state.[11] In humans and lab animals that have developed an addiction, alterations in dopamine or opioid neurotransmission in the nucleus accumbens and other parts of the striatum are evident.[11] Studies have found that use of certain drugs (e.g., cocaine) affect cholinergic neurons that innervate the reward system, in turn affecting dopamine signaling in this region.[62]

Summary of addiction-related plasticity[edit]

Reward system[edit]

Main article: Reward system

This section needs expansion. You can help by adding to it.(August 2015)

Mesocorticolimbic pathway[edit]

Understanding the pathways in which drugs act and how drugs can alter those pathways is key when examining the biological basis of drug addiction. The reward pathway, known as the mesolimbic pathway, or its extension, the mesocorticolimbic pathway, is characterized by the interaction of several areas of the brain.

  • The projections from the ventral tegmental area (VTA) are a network of dopaminergicneurons with co-localized postsynaptic glutamate receptors (AMPAR and NMDAR). These cells respond when stimuli indicative of a reward are present. The VTA supports learning and sensitization development and releases DA into the forebrain.[64] These neurons also project and release DA into the nucleus accumbens,[65] through the mesolimbic pathway. Virtually all drugs causing drug addiction increase the dopamine release in the mesolimbic pathway,[66] in addition to their specific effects.
  • The nucleus accumbens (NAcc) is one output of the VTA projections. The nucleus accumbens itself consists mainly of GABAergicmedium spiny neurons (MSNs).[67] The NAcc is associated with acquiring and eliciting conditioned behaviors, and is involved in the increased sensitivity to drugs as addiction progresses.[64] Overexpression of ΔFosB in the nucleus accumbens is a necessary common factor in essentially all known forms of addiction;[1] ΔFosB is a strong positive modulator of positively reinforced behaviors.[1]
  • The prefrontal cortex, including the anterior cingulate and orbitofrontal cortices,[68] is another VTA output in the mesocorticolimbic pathway; it is important for the integration of information which helps determine whether a behavior will be elicited.[69] It is also critical for forming associations between the rewarding experience of drug use and cues in the environment. Importantly, these cues are strong mediators of drug-seeking behavior and can trigger relapse even after months or years of abstinence.[70]

Other brain structures that are involved in addiction include:

  • The basolateral amygdala projects into the NAcc and is thought to also be important for motivation.[69]
  • The hippocampus is involved in drug addiction, because of its role in learning and memory. Much of this evidence stems from investigations showing that manipulating cells in the hippocampus alters dopamine levels in NAcc and firing rates of VTA dopaminergic cells.[65]

Role of dopamine and glutamate[edit]

Dopamine is the primary neurotransmitter of the reward system in the brain. It plays a role in regulating movement, emotion, cognition, motivation, and feelings of pleasure.[71] Natural rewards, like eating, as well as recreational drug use cause a release of dopamine, and are associated with the reinforcing nature of these stimuli.[71][72] Nearly all addictive drugs, directly or indirectly, act upon the brain's reward system by heightening dopaminergic activity.[73]

Excessive intake of many types of addictive drugs results in repeated release of high amounts of dopamine, which in turn affects the reward pathway directly through heightened dopamine receptor activation. Prolonged and abnormally high levels of dopamine in the synaptic cleft can induce receptor downregulation in the neural pathway. Downregulation of mesolimbic dopamine receptors can result in a decrease in the sensitivity to natural reinforcers.[71]

Drug seeking behavior is induced by glutamatergic projections from the prefrontal cortex to the nucleus accumbens. This idea is supported with data from experiments showing that drug seeking behavior can be prevented following the inhibition of AMPA glutamate receptors and glutamate release in the nucleus accumbens.[68]

Reward sensitization[edit]

Target
gene
Target
expression
Neural effectsBehavioral effects
c-FosMolecular switch enabling the chronic
induction of ΔFosB[note 2]
dynorphin
[note 3]
Categories: 1

0 Replies to “Addiction Problems Essay”

Leave a comment

L'indirizzo email non verrà pubblicato. I campi obbligatori sono contrassegnati *