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In this post, we shall discuss the genetic influence of drug addiction. We shall examine neurobiology relating to drug addiction. We shall also examine the value of genetics when it comes to developing specific strategies for overcoming drug addiction.
Drug addiction essentially does have a genetic component. Thus, it’s essential we attempt to understand this genetic component of drug addiction. It’s even more essential that we attempt to develop therapeutic methods that are influenced by the information we are able to take from genetic studies and drug addiction.
Before we launch into this discuss, we shall begin by defining drug addiction. There exists confusing nomenclature when it comes to the definition of drug addiction. Some experts believe addiction is a disease of the mind, whilst others believe addiction is essentially a choice. For instance, an addict may choose to take drugs to mask anxiety that arises due to trauma the addict suffered during his or her past.
The World Health Organization defines drug addiction as “the use of a drug in a manner that’s not medically or socially approved”. We feel this definition is fairly general, and not particularly useful for practical purposes. This definition essentially says drug addiction arises when a person uses drugs for non-medicinal purposes. However, many people who use drugs for medicinal purposes are also addicted to the particular drug or drugs they are taking.
Another term of interest is ‘drug dependency.’ The official pharmacological definition of drug dependency is “persistent use resulting in adaptations typically accompanied by accommodation or tolerance and withdrawals.”
This definition focuses on the brain and how the body responds to drug addiction. When you use drugs over and over again, the body tends to adapt. The body essentially accommodates to drug abuse and tolerance occurs. In order to maintain the desired ‘buzz’ created by the drug, the user must increase the amount of the drug that’s consumed.
This is known as a ‘compensatory escalation.’ When a drug addict stops taking the drug, withdrawal symptoms are experienced, since the body is over-compensated for the drug in question. This manifests itself in the form of withdrawal symptoms. These symptoms are both psychological and physical in nature. Example physical withdrawal symptoms include cravings, seizures and nausea. Psychological withdrawal symptoms include anxiety, depression and insomnia.
One of the most unfortunate example of withdrawals is when a newborn baby experiences withdrawals because the mother has abused drugs such as methadone or heroin during the pregnancy. Once the baby is born, the baby will no longer have access to these drugs so withdrawal symptoms will arise.
We consider drug addiction to be a form of pathological decision making. Drug addiction is characterised by compulsive destructive behaviour despite extreme negative consequences. That’s why family members of drug addicts shake their heads and ask their loved one ‘why are you doing this to yourself?’
The drug addict may have lost his or her children, health, job and been sent to jail because of the addiction. However, the addict continues to use drugs despite these extreme negative consequences. This is not just expressed in terms of drug addiction. These people often suffer from other negative behaviours such anti-social behaviour and engaging in violence. If we analyse the prison population, it’s not surprising to find that the majority of these people are drug addicts. Thus, drug addicts have the propensity to make bad decisions when compared to others.
The main challenge for society is to successfully treat people addicted to drugs. One strategy is to provide education to drug addicts as a means of helping them overcome their addiction to drugs. This approach assumes we can educate people ‘out’ of their drug addiction. This aims to teach these people why taking drugs is a bad decision and then aims to teach them how to make good decisions.
However, education is known to be fairly ineffective at treating people for drug addiction. This is because drug addiction is not caused by mere ignorance. It’s thus essential to drill down further rather than merely intellectually outlining why drug addiction is bad.
There is a clear need to target the source of the biological cause of drug addiction. We must determine what’s occurring on a biological basis and then figure out what perpetuates drug addiction even though the addict is experiencing extreme negative consequence as a result. We need to figure out the vulnerable genetic systems involved when drug addiction arises, and then aim to strengthen those systems through effective prevention strategies and treatments.
Now we shall examine the genetic component of addiction. Studies prove that genetic factors account for around 40-60% of addiction. The other 40-60% of addiction is due to environmental factors. This means a person may be vulnerable to drug addiction, but this vulnerability does not equate to inevitability.
Addiction clearly clusters in certain families. This means nearly everybody in certain families will be addicted to one substance or another. This observation prompted researchers to believe that addiction must have a genetic component to it. But families suffering from drug addiction also experience similar environment cues. If these environment cues were absent, we may conclude that the addiction in question would never have arisen.
How can we use genetics to understand prevention and treatment of drug addiction? The answer is simple. We must implement better assessments of genetic vulnerabilities and then focus on strategies that address these vulnerabilities.
One day it is hoped we will be able to detect each gene that’s responsible for drug addiction. This would allow us to apply specific strategies to address each individual genetic weakness that causes drug addiction. These genetic characteristics would be identified via screening. Once these genetic weakness are located, we can then develop strategies that may compensate for these weaknesses.
Genes are made up of DNA strands. DNA strands are essentially molecules. These molecules are tied together by ‘base pairs’, also known as nucleotides and nucleosides. DNA is read or ‘transcribed’ using enzymes and chemical reactions. This allows DNA to be read and transcribed and read by other complementary molecules known as messenger RNA. RNA is then read and turned into proteins. This is known as translation. Proteins consist of amino acids. Messenger RNA helps to configure this sequence. In your body, there consists anywhere between 30-50,000 different protein molecules.
Every human being has similar genes. However, when these genes differ, this is known as polymorphisms. Poly means ‘multiple’ and morphism means ‘expressions.’ Polymorphism thus means ‘multiple expressions of genes.’ These variance in DNA means we are all unique individuals.
Some polymorphisms cause disease. Here, polymorphism means the associated protein no longer does it’s job correctly. However, polymorphism is also associated with drug addiction. When this was first discovered, some believed it was possible to correct this polymorphism and the resulting abnormal protein so that drug addiction would be ‘cured.’ Meta-analyses of several studies reveal this is certainly easier said than done.
Addiction is thought to be related to over a hundred different polymorphisms. This tells us that the genetic basis of addiction is extremely complicated. There is no ‘addiction gene’ but rather many ‘addiction genes.’ Addiction is complicated with many different pieces to it.
Once genes are discovered in a laboratory, a process known as ‘micro arrays’ may be used to identify the expression pattern associated with messenger RNA and proteins. This allows us to map polymorphisms relating to addiction and the variance proteins that are formed as a result of this polymorphism.
This may allow us to one day conduct genetic screening, and then advise people that they have certain polymorphisms in certain genes that make them vulnerable to addiction. Thus, microarrays may be used to assess people’s vulnerability to developing an addiction.
Firstly, polymorphisms may increase your odds of starting to abuse drugs in the first place. This is thought to be associated with reward systems located in the brain. If a person has a polymorphism relating to the reward they experience when a drug is consumed, they may be more inclined to use the drug more often than a person without this polymorphism in the reward system.
Another polymorphism may relate to regions of the brain that causes a person to experience pain. Around a third of drug addicts begin to take drugs for pain relief. This pain may be physical or psychological. This may mean the person is attempting to treat an underlying emotional problem. For instance, a person who was abused as a child may take drugs to relieve anxiety these experiences have caused. If a person has a polymorphism that makes them feel anxiety or depression, then clearly this person is also more vulnerable to developing a drug addiction.
A lot of polymorphisms relate to the management of a neurotransmitter known as dopamine. Dopamine is a chemical in the brain that directs goal-seeking behaviour and the anticipation of pleasurable experiences. Dopamine-related polymorphisms are believed to increase the odds of becoming addicted to drugs.
Lastly, there may also be polymorphisms relating to specific drugs. For instance, you may have a particular polymorphism making you more vulnerable to developing a nicotine addiction. Thus, a polymorphism may be associated with a specific drug.
Now we shall discuss what specific polymorphisms and abnormal proteins exist that make drug addiction more likely to occur.
The first polymorphism we shall discuss related to metabolising enzymes. These enzymes break other molecules down. For instance, an enzyme originating in the liver known as cytochrome p450 is used to metabolise drugs such as nicotine. Studies prove that polymorphism in this enzyme increases the odds of becoming addicted to nicotine. Therefore, there’s is a relationship between how quickly your body may break down these drugs and your odds of becoming addicted to drugs.
The second polymorphism we shall discuss relates to the synthesis of dopamine. To recall, dopamine is known as the ‘reward neurotransmitter.’ Studies prove there as polymorphism in the brain for proteins that synthesise dopamine and determines how much dopamine is made. Variance in the enzyme responsible for dopamine production is thought to make people more vulnerable to addiction.
Thirdly, polymorphism also affects dopamine receptors. This polymorphism alters the response to dopamine being released as a neurotransmitter.
Fourthly, polymorphism is believed to alter cognition. Altering cognitive functions may also make a person more vulnerable to drug addiction and drug abuse. This is because this genetic variance diminishes the person’s decision-making abilities.
Fifthly, polymorphism also affects a person’s impulsiveness. This affects how the person reacts to stress and changes. Polymorphism affecting a person’s impulsiveness makes the person more vulnerable to do something really stupid that gets the person into trouble. This, polymorphism determines whether you will be an impulsive person or whether you are the type to think about your actions thoroughly before you act. Impulsiveness is a major risk factor when it comes to drug addiction.
Now we shall discuss how polymorphisms affect decision-making and cognition. The major parts of the brain affecting cognition include the pre-frontal cortex (PFC), the orbital frontal cortex (OFC), the Amygdala and the nucleus circumvents.
The PFC is the brain’s centre for decision-making. This is where information is processed. This allows us to respond to cues taking place in our environment. The PFC helps us determine what we are going to do and what we are not going to do. This is why the PFC is known as the “Go, No Go” part of the brain.
The OFC is known as the salient structure of the brain. This is because the OTC allows us to establish priorities. The OFC transfers information into the PFC so when the PFC makes decisions, it’s based on what you consider to be important to you. This means you prioritise things that are important, whilst you procrastinate on or ignore less important things.
The amygdala is about impulsiveness. It directs behaviours that relate to rewards and emotional requirements. The amygdala directs behaviours that are associated with short-term rewards. The amygdala allows us to make decisions ‘on the spot’ rather than giving us time to think these decisions over.
The PFC may take priority over the amygdala, meaning more rational decisions are prioritised over short-term decision making. Thus, the PFC acts as a brake to impulsiveness. When an addiction arises, a condition known as hypofrontality occurs. This is when the pre-frontal cortex reduces in size. This is characterised by poor control of impulsivity and reward systems. The OFC is also affected. This means drug use is prioritised above and beyond more important tasks. Thus, cognition and the ability to make good decisions is compromised when an addiction arises.
This means the brains of people addicted to drugs are rewired as a result of the addiction.
PET scan analysis conducted on drug addicts’ brains show a deficiency in the number of dopamine receptors. Dopamine is the neurotransmitter associated with rewards. This means these people have a weakened ability to experience rewards due to under functioning dopamine receptors. Studies prove this is due to a genetic vulnerability and due to the use of drugs. People who have a genetic variance that causes an under-functioning dopamine receptor in the reward pathways are more likely to become addicted to drugs.
However, drug use itself is responsible for the suppression of dopamine receptors. This is a good example of how genetic and environmental factors work together to cause or prolong drug addiction.
Studies show the powerful effects genetics has on our ability to make decisions. For starters, genetics influence the way we perceive events taking place in our environment. Genetics also plays a part in our ability to understand consequences. Lastly, genetics also influences our ability to carry out planning.
Genetic variance may compromise our ability to make sound decisions because of the above factors. For instance, a genetic variant may cause a person to struggle to comprehend consequences of certain actions or to lose the ability to carry out sound long-term planning. This will prevent the person from appreciating long-term consequences of certain activities and also prevent them from learning from previous experiences. Thus, altered genes also alter the ability to learn from our environment. It’s not hard to see why genetic variants can thus cause drug addiction by altering a person’s cognitive abilities.
Genetic variance may also cause a person to be more of a risk taker, and we would expect risk takers to experience a higher occurrence of drug addiction compared to people without this genetic variance. Risk takers often take risks due to the ‘rush’ they experience when a risky activity is experienced. They claim they cannot experience pleasure by engaging in ‘normal’ activities. To engage their reward system, they have to engage in risky activities such as drug use.
Genetic expression refers to how our genes express themselves after they have formed. Studies show that drug use also interferes with genetic expression. For instance, if a teenager uses drugs, they will also interfere with how their genes express themselves in later life.
When you analyse the brain of a sixteen-year-old to that of a thirty-three-year-old, you will see that the biggest difference is in relation to the pre-frontal cortex that we explained above. This is because of maturity and myelination of brain pathways. This means teens have an under-functioning pre-frontal cortex that makes them more vulnerable to drug abuse. This is compounded by the fact the teen amygdala is fully functioning whilst the pre-frontal cortex is still developing. This means teens are much more likely to engage in impulsive behaviours.
If a teenager takes drugs when the pre-frontal cortex is forming, then the drugs may influence these changes via genetic expression. This means the normal development of the pre-frontal cortex is compromised. This means teen drug addicts may weaken their decision-making ability later on in life.
This is why many former drug addicts continue to make bad decisions in later life, even when those decisions do not relate to drug use. Some refer to this as the “Peter Pan” effect when drug addicts never appear to grow up. Thus, drug-induced altering of genetic expression inflicts long-term negative effects for teen drug users.
Understanding genetics and addiction help us determine vulnerabilities and risks people face as a result of their genetics. It also provides us the ability to assess specific individuals for specific genetic weakness. One day it is hoped this screening will allow scientists to recommend specific treatments that cater to specific genetic weaknesses that cause drug addiction.
Figuring out the genetic component of addiction will also help us develop preventative strategies before an addiction arises. Screening for genetic weakness will allow us to inform individuals of this fact so they may take steps to avoid developing an addiction in the first place.
We may also be able to develop medications that address specific genetic vulnerabilities that give rise to drug addiction.
We hope you enjoyed this article on addiction and genetics. If you or a loved one suffer from an addiction to drugs contact Rehab 4 Alcoholism today for rehab in London.
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