Science of Addiction

The understanding of addiction is continuously developing and has been completely rethought by the medical community as having implementations as a medical disease rather then psychological. Major contributors to this paradigm shift stem from research through high-resonance imaging that showed drug addiction causes physical changes to the brain. Heredity links and neurological chemical balances have also been correlated with higher chance of addiction. Understanding addiction’s science contributes to the treatment of it beyond the medical world, to the social and political world. Is it in an addict’s volition to break a habit, or is it a physical disease that requires more than will?

Ten Universities in the US have introduced accredited residency programs (through ABAM, the American Board of Addiction Medicine) specializing in addiction medicine, taking on the postmodern belief. Upon completing medical school and primary residency, doctors could spend a year studying the neurological science of addiction. David Withers of Marworth Alcohol and Chemical Dependency Treatment Center claims, “This is a first step toward bringing recognition, respectability, and rigor to addiction medicine.” A goal of such programs would be to introduce doctors as specialists in addiction, diversifying a very wide field. Certainly these specialists will cover a wide range of substances including alcohol, legal and illegal drug use, tobacco and nicotine. It’s unknown if there knowledge will expand to gambling, self-harm, sex, food, caffeine, videogames, internet, television and other less mentioned compulsions of many addicts.

Knowing more about what’s entailed in addiction may lead to better diagnosis. It may also help treatment, which often is ended only to find relapse in patients. While most diseases are checked up on annually, and not presumed to be cured, addiction is often forgotten about in patients. A science behind addiction could potentially redirect much of psychiatrists’ work to others with a better understanding. This switch might help reduce false diagnosis and unnecessary prescribing of medication, a massive problem. Having specialists who know the legality of substance use could lead to a restructuring of substance regulation, with change in restrictions, based on reason and scientific findings.

Basic chemical processes in reward

Substances involved in addiction are made of chemicals and reasonably able to be thought of scientifically. The past two decades have brought much greater understanding of the pathways drugs take. Studying people and animals have also shown what parts of the brain are altered by use, some of which are not affected through immediate use.

Drugs mimic the chemical structures of natural neurotransmitters, making them activate neurons unnaturally through consumption. Cognitive functions are changed through perception and/or emotion in the body through this alteration in sending, receiving, or processing of chemicals. The further from a natural neurotransmitter the mimicking chemicals are, the more different the messages sent will be from a natural feeling. This can lead to chemical imbalances, a change in neural production of neurotransmitters, and change in receptors, affecting the user even after the drug is depleted. Typically a tolerance is built. Drugs also sometimes work by causing changes to nerves to either release natural neurotransmitters or prevent them from re-uptake so that neurons can shut off. Both changes cause an enhanced message. 

The mentioned cognitive changes from substance use lead to changes in the brain’s reward system through increased dopamine and often serotonin. Dopamine functions as a neurotransmitter which can activate various dopamine receptors, and as a neurohormone that inhibits prolactin, a protein that is involved with sexual gratification amongst other bodily functions. Increasing dopamine can increase heart rate and blood pressure, as well as create various changes in regulation of movement, sensation, cognition, motivation, and euphoria. Typically the substance abused changes the reward system in a manner that elates the user and they are tempted to reuse. At a certain point, activities considered pleasurable are done compulsively, often considered the point of addiction.

Understanding addiction is aided by knowing the difference between the “liking system” and “wanting system.” Something is liked after it elates the user and the reward is received, and wanted when the pleasure is anticipated and behavior is motivated towards getting it. Wanting is referred to as the mesolimbic dopamine-serotonin phenomenon. In addicted patients, there is a much greater motivation from the wanting system, and often little to no pleasure from the liking system, leading to uncontrollable urges.

Repeated use of something forces the brain to become sensitized to the substance or act. This typically comes from increased or decreased receptors in different areas of the brain, and less natural production of neurotransmitters.

Because each drug has a different process, they each cause different changes in the brain. An interactive flash called Mouse Party briefly goes into a simplified explanation of the mechanisms of various common drugs and how they affect the reward pathway. It can be found here:

Physical versus Psychological Dependencies

Addiction refers to dependence on something that is physically or psychologically habit-forming. Substance dependence usually entails compulsive and repetitive use despite significant substance-related problems, increased tolerance to the substance, and withdrawal symptoms when use is reduced. Dependencies in addiction are often divided into physical and psychological dependencies. When less than 3 of 7 criteria for addiction under the DSM IV-TR are met, a diagnosis may for substance abuse instead of addiction.

Physical dependencies, common to some drugs use, are categorized by highly unpleasant physical withdrawal symptoms. Physical dependencies may be referred to as physiological and chemical dependencies. Physical withdrawal symptoms include pain, muscle tension, sweating, nausea, vomiting, diarrhea, difficulty breathing, and palpitations. Opiate use is commonly an entirely physical dependence. Psychological dependence is categorized by dependence of the mind. Psychological withdrawal symptoms include cravings, irritability, insomnia, depression, headaches, and anorexia. Gambling and cocaine use are nearly always an entirely psychological dependence.

Both withdrawals can be deadly when severe withdrawal leads to hallucinations, delirium tremens, strokes, seizures, and heart attacks. While addictions can purely be a physical or psychological dependency, they typically carry symptoms of both to different extents. Addictions are more common with physically addictive substances because the substance is used for its pleasurable feeling of removing withdrawal, on top of the desired effect of the substance. Cigarettes, a common example, are often used by addicts for nicotine withdrawal more than the pleasant feelings originally associated with smoking. In the past, the medical field has made little distinction between types of dependencies, since both derive from physical changes to the brain, leading to similar treatment in both types.

Brain Restructuring – Contributions of High-resonance Imaging

There are multiple changes expressed in the brains of people with addictions compared to those without, making their brains distinctly different. Regardless of how natural a receptor-active drug is, they always work by deceiving the brain. So, the amount of neurotransmitters and receptors, chemical balances, ways genes are expressed, and connections between parts of the brain can all be altered through minor addictions. Major addiction changes perception through the ability to encode and retrieve information.

The ventral tegmental area (VTA) has a pathway to the nucleus accumbens which dopamine passes through for the reward system to function. The artificial stimulation of this pathway is different based on the make-up of the brain. Damage to the insula, a part of the cerebral cortex involved in sensation, has been proven to reduce addiction. This has been shown in smokers who receive strokes damaging the insula, commonly losing nicotine cravings while other natural cravings exist (such as for food and sex), as well as in lab rats who have stopped self-administering amphetamines after brains are anaesthetized. The reciprocal connections between the insula and VTA suggest that both are involved in mediating addiction.

Factors of addiction

The brain is genetically predisposed in certain people to gain addictions. The differences in how genes are expressed and metabolized, and amount of neurotransmitters, are all factors of a person’s disposition. Changes could alter a person’s comfort in risk-taking, their impulsivity, and many other factors in how susceptible someone is to addiction. While it is not a surprise that the brain affects chance of addiction, it is uncertain to what extent it is hereditary, such as being born with a disposition of compulsivity and being at the risk of self-harm, or if their surroundings cause their brains to mold in that way.

Drugs which act quicker are typically more addictive. There is correlation between delivery-method and how addictive a drug is, with smoking being the quickest method of delivery, followed by injecting into a blood vessel, snorting or sniffing, and lastly ingestion. Quicker delivery is more likely to cause changes to regions of the brain associated with addiction. Hence patches are used to quit smoking, which takes longer to act and prolongs the effects to reduce withdrawal.

Culture and social groups are great factors of addiction. Addiction being a norm in someone’s surrounding increases chance of that person trying the substance or act. Race, education status, and peer’s ability to quit use is correlated with a user’s ability to quit. There have also been clear correlations between stress and trauma, especially at young ages, and later drug use. Resistance to substances could be avoided by emphasizing lesser use. This may mean a switch from vodka to wine, or drinking only after dinner. Cultures which place emphasis on moderated use and do not make abuse very accessible thus aid in removing factors of addiction.

Other biological factors have been shown through correlation. Males are more likely to abuse drugs than females. Chances of drug addiction are increased further by family members having addiction or common use. This may stem from the carrying of a specific version of a gene for a specific serotonin transporter being inherited or through seeing addiction as normal. Mental illness, such as bipolar disorders, is both more likely to be inherited if family members carry it, and associated with addiction rates.

Stress often leads to cravings and relapse. Many subscribe to the belief that certain individuals abuse drugs, including alcohol, in an attempt to self-medicate an unpleasant state of mind. This idea was popular even before 1884 when Freud noted that cocaine was used by many for its anti-depressant properties. Self-medication theory implies that a person’s particular choice of drug is chosen because it relieves their displeasure, such as patients with PTSD self-medicating through alcohol or opiates.

While addiction stems from gene interaction, not a single gene, looking at genetic factors in inheritance of certain genes helps expose who is more at risk of addiction. Many animals self-administer intoxicating substances just as humans would when taught how to abuse a substance. This has led to many findings. For example, alcohol and cocaine addicted people are more likely to carry the A1 allele of the dopamine receptor gene DRD2. Mice lacking gene Htr1b, a serotonin receptor, are more likely to use cocaine and alcohol. People with two copies of the ALDH*2 gene are extremely unlikely to become alcoholics. Mice with lower levels of neuropeptide Y are likely to drink higher amounts of alcohol, and with defective Per2 genes drink three times the normal amount of alcohol. Gene CYP2A6 is found in non-smokers and produces nausea and dizziness from smoke.

Possible Addiction Treatments – Psychological versus Physical

Treatment typically uses a psychological approach through counseling or a maintenance approach through lowering dosage or creating a new-dependency. Counseling is the most common treatment for addiction. This is because internal brain changes can only occur when the addict accepts the need for change. It should be noted that the majority of addicts able to overcome addiction do so without any outside help. More dependent drugs require more attention, so while more than 90% of ex-smokers quit on their own, less than half of alcoholics are able to quit on their own.

Psychological therapy is diverse in its methodology. Cognitive behavioral therapy (CbT), a talking-based treatment for addiction, attempts to teach addicts about their use and decision-making process and motivate healthier patterns. Aversion therapy attempts to condition an addict to have positive or negative stimulus to actions, such as nausea or bad thoughts from use to reduce the desire to abuse.

The most commonly used treatment for addiction, and believed by many as the most-effective, are self-help programs such as Alcoholics Anonymous and Narcotics Anonymous. AA and NA, both group therapy programs, treat any substance’s addiction similarly and rely heavily on a moralistic approach and anonymity. AA and NA receive criticism for asking addicts to gain personal relationships with a “Higher Power” and are often regarded as attempts to proselytize religion. However, AA and NA were amongst the first group to consider addiction a disease and had heavy emphasis that addicts are responsible for treating themselves.

Drugs are used in detoxification to alleviate withdrawal symptoms, such as pain killers. Buprenorphine, a drug sold under many brand names, is often used to treat withdrawal symptoms of opioid users even though it can be equally as addictive and have many other side effects. These drugs are intended to help detoxification by suppressing the central adrenergic activity.

Maintenance programs, which are highly used for drug-addicted patients, involve prescribing drugs to reduce dependency. The same substance as the addict is dependent on is sometimes given. Other times less harmful drugs are given. Agonist of partial agonist analogs (substances which activate the same mechanism) of the addictive drug help in weaning patients. Heroin users are often given methadone and smokers are often given nicotine patches or inhalers. Anticraving medications, such as naltrexone in alcoholism, reduce withdrawal symptoms and may be administered.

Conversely, drugs may be used to prevent use and not take care of withdrawal symptoms. Antagonists may be used which block effects of a substance, such as Naloxone which blocks heroin’s effects. Disulfiram, a drug used to reduce alcoholism, creates a buildup of acetaldehyde which makes the user become sick upon drinking alcohol. Some reward-blocking medications exist but are not used because they reduce pleasure in users. Some immunizations are being developed which would create antibodies that remove a substance before it reaches the brain.

Enforcement of treatment, as well as the desire for and belief in the treatment, are essential to aid. There is no certainty whether self-help or psychological therapy, individual or group therapy, going cold-turkey or lowering dose, or even switching to alternative substances is better for a patient. Multiple therapies may be used, and it is possible that only one treatment will suffice to remove a patient of their addiction.


Regardless of whether drug addiction comes from nature or nurture, it is a disease that is often under treated. Addiction has gotten to be so common that the death rates associated with lung cancer caused by smoking are higher than the combined death toll of colon, breast, and prostate cancer victims. Adding specialists who are knowledgeable of addiction to the list of tools to treat addiction is highly beneficial and could hopefully reduce this massive social problem. A better understanding of addiction could potentially lead to better treatment of individuals, and a better understanding of dependency.