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The Science Behind Drug and Alcohol Addiction

by Landmark Recovery

August 20, 2018
A woman studying DNA slides

Drug and alcohol addiction are two iterations of addiction, which is clinically defined as a chronic, relapsing brain disease in which the user compulsively seeks to use their outlet of choice despite the harmful consequences that ensue. With substances like drugs and alcohol, the brain’s structure becomes physically changed which can lead to harmful, self-destructive behavior in the pursuit of the addiction.


How/Why Do We Study Drug And Alcohol Addiction

A woman studying DNA slides

Drug and alcohol addiction is estimated to cost the United States more than $700 billion per year in lost productivity, health care costs, and crime. Each year, abuse of drugs and alcohol play a part in the death of more than 90,000 Americans, while tobacco and associated products are linked to an estimated 480,000 deaths per year. The Centers for Disease Control and Prevention report that in 2016 there were more than 72,000 unintentional drug overdoses in the United States, a number that has been increasing every year since 1999. Addiction destroys families and communities by rewiring people into slaves to substance use. For thousands of years humanity has dealt with the problem of addiction, but in recent centuries science has made such exponential progress that every day we are closer to understanding and solving the mechanisms of addiction in the human brain.

Today, the National Institute on Drug Abuse categorizes the term “addiction” under the umbrella category of substance use disorder or SUD. The symptoms of substance use disorders fall into four major categories: impaired control, social impairment, risky usage, and developing withdrawals/tolerance. These symptoms help clinicians to distinguish whether someone has an addiction or not, but it has also opened the door to further addiction classifications that seem to adhere to these criteria but do not involve drugs or alcohol, for example, sex and video game addiction. The Diagnostic & Statistical Manual of Mental Disorders characterizes addiction to an intoxicating substance as having at least two of the following symptoms within a 12-month period:

  1. The substance is taken in larger amounts and for a longer period than was originally intended
  2. The person has a consistent desire to quit but is unsuccessful in cutting down or controlling their usage of the substance
  3. A significant amount of time is spent on activities that lead to obtaining the substance, using the substance, and recovering or coming down from the substance.
  4. The person has a craving or strong desire to use the substance often.
  5. Usage of the substance has the person failing to fulfill major role obligations at work, home, school, or in their social life.
  6. The person continues to use the substance despite all the negative consequences that ensue. This could be persistent social or interpersonal problems that are made worse by the person’s substance use.
  7. Formerly important activities, events, and work obligations are either given up or relegated to secondary status with substance use taking precedence.
  8. The person frequently uses the substance in situations or environments when it is physically hazardous
  9. The person continues to use the substance despite knowing they have a psychological problem that is related to their substance use.
  10. The person develops a tolerance to the substance that is marked by either a need for increased dosages of the substance to achieve desired intoxicating effects or a noticeably diminished intoxicating effect with continued use of the same dosages.
  11. The person has withdrawal symptoms that are specific to that substance, and they continue to use the substance to relieve or avoid these symptoms.


Addiction vs. Abuse vs. Dependence vs. Physical Dependence

The National Institute on Drug Abuse also distinguishes between addiction and abuse. According to the organization, it becomes substance abuse when people use illicit or prescription drug inappropriately, which could include repeated use of the drug to produce pleasure, reduce stress, or avoid reality. It also includes using prescription medication outside of the clinically recommended guidelines or using someone else’s prescription medication. NIDA defines addiction as beginning when a person cannot control their impulse to use a substance despite the negative consequences. Using the Diagnostic Statistical Manual for Mental Disorders, we can identify the symptoms of addiction and correctly diagnose it.



Addiction occurs when the person meets the criteria laid out by the Diagnostic Statistical Manual for Mental Disorders. These criteria boil down to whether a person continues to use the substance despite the direct negative consequences it causes.



Abuse is any substance use that falls outside the limits of clinically recommended guidelines, or that is used to produce pleasure, reduce stress, or avoid reality.



This is when the person relies on the substance, either as a daily cure for reducing stress, getting through social situations, or coping with reality. Dependence does not necessarily mark an addiction, as someone could have a dependence on a substance but still choose not to use it.


Physical Dependence

Physical dependence is different from regular dependence. Physical dependence occurs when the body adapts to regular exposure to the substance and when that substance is taken away it begins to experience withdrawal symptoms. Physical dependence may persist even when the desire to take the substance is gone. A person may only take the substance to avoid the painful withdrawal symptoms.


Voluntary Behavior

The initial decision to try a substance is mostly voluntary due to different environmental pressures and situations. However, once a substance has gotten hold of a person’s brain, their ability to exert self-control becomes drastically reduced. Brain imaging studies have shown that people with severe substance addictions have noticeable differences in brain structure related to the areas that control judgment, decision making, memory, learning, and behavioral control.


Understanding the Science of Addiction

A woman studying genes related to addiction

With the discovery of Maged1, a gene responsible for predicting cocaine addiction in lab rats, scientists are one step closer to uncovering the exact genetic components that are responsible for determining addiction in people. In fact, research has revealed more and more evidence that genes could be the most substantial factor for a person developing an addiction.

Joni Rutter, director of the Division of Basic Neuroscience and Behavioral Research at NIDA, says that about 50% of addiction risk is genetic, within a range of about 40-60%. When it comes to alcoholism, the children of people dependent on alcohol are 3-5 times more likely to develop the disorder than the rest of the population, regardless of whether their alcoholic parents raised them or adopted by non-alcoholics. Scientists believe that genetics could play a more significant role in alcoholism than for addiction to other substances, being nearly 60% heritable. Here are some of the most prominent genetic and physiological factors that can influence a person’s risk for addiction.



Some disorders are also significant predictors for the risk of addiction. We know that roughly half of the people with a substance use disorder also have an additional psychiatric diagnosis, typically related to a general anxiety disorder or antisocial personality disorder. The myth of an addictive personality doesn’t hold as much weight when you examine the genetic and psychological underpinnings of addiction.

For example, the personality disorder most commonly associated with addiction is an antisocial personality disorder. One study found that 18% of people with a substance use disorder also have an antisocial personality disorder and only 4% of the non-addict population having this disorder. An antisocial personality disorder is characterized by dishonesty, manipulation, and criminal behavior. However, some characteristics such as being extremely sensitive and extremely cautious are also risk factors for being an addict.

When we see that addiction comes down to different genetic factors and psychological underpinnings, we can begin to understand why rehabilitation is so tricky. Unlike other diseases, addiction requires treatment that is specifically built around a person’s circumstances.


Physiological Factors

Psychological disorders are not the only genetic indicators for addiction. One of the strongest genetic risk factors for alcoholism is linked to metabolism. The specific genes related to alcoholism are responsible for encoding proteins that convert alcohol into acetaldehyde and eventually acetate. This by-product is nauseating and toxic, and genes that slow down the metabolism of this byproduct make people feel nauseous even after just light drinking.

One of these genes, ALDH2, is particularly prominent in the Asian population. One meta-analysis of 4500 Asian participants found that those with this gene were nine times less likely to develop alcoholism than those with variants of this gene.

One gene that is highly correlative with nicotine addiction is CHRNA5 and acts oppositely to the way ALDH2 does for alcohol. Having just a single variant of this gene doubles your risk of nicotine addiction. What the gene does is offsets the unpleasant or displeasing facets of smoking cigarettes. People with a variant of the CHRNA5 gene can smoke cigarettes without feeling as disgusted or off-put by the taste, smell, and side effects. One study using comatose mice found that the gene was activated in regions of the brain associated with avoidance and aversion. Heavy smoking could even permanently damage the neurons in this region, which would create feelings of anxiety and distress in the user, causing them to become even more reliant on cigarettes possibly.



A young child looking out a window

Science has only recently begun to understand the complex role that our changing environment has on our previously thought to be static genes. Epigenetic mechanisms describe how our environment influences our bodies. In other words, it’s the study of changes in the regulation of gene activity and expression as it is affected by environmental factors such as chronic stress, drug exposure, or childhood trauma. These types of modifications to your genetics can even be passed along to children. For example, children of Holocaust survivors were found to have inherited the stress of their parents well after they had escaped concentration camps.

Another factor affecting addiction risk is childhood trauma. Severe stress in early life is known to increase the risk for developing some substance use disorder significantly. One Swedish study found that children that lost their parents at a young age experienced a parent’s cancer diagnosis, or witnessed domestic violence had twice the risk of developing a substance use disorder. Continual distress, or chronic stress, can rewrite the way that our brain deals with stress.

Youth are particularly susceptible to developing and sustaining a drug addiction into adulthood. Although drug use can happen at any point in a person’s lifetime, drug use typically starts in a person’s youth. The brain is at a developing stage and is more at risk to develop unhealthy coping mechanisms. The functions associated with executive decision making and impulse control are also among the last to completely mature. Multiple studies have shown that frequent marijuana use in adolescence can increase the risk for psychosis in later adulthood.

Numerous studies have also found that youth with untreated ADHD are also at increased risk for developing a substance use disorder. This poses a problem to clinicians attempting to medicate this disorder with drugs like Methylphenidate or Amphetamine. Patients could potentially develop addictions to these stimulants, whether or not they have correctly diagnosed with ADHD. Although no definitive conclusion has been reached, there has been no study showing that taking prescription medication to treat ADHD raises risk for addiction for people with this type of disorder.


In Conclusion

We still have a ways to go before there is more mainstream acceptance of addiction’s strong genetic component. In the meantime, researchers and scientists have dedicated themselves to isolating and understanding the exact genetic expressions that are responsible for addiction, hopefully paving the way for better treatment. If you’re struggling with addiction and wish to learn more about residential inpatient treatment, don’t hesitate to reach out to the team at Landmark Recovery.

Addiction destroys the body and weakens the spirits. Landmark Recovery is a place where people struggling with chemical dependency problems can find answers to the issues that have tormented them for months, years or decades. Our dedicated clinicians, nurses and medical staff will help you or your loved one find solutions that work for a lifetime. Call one of our caring admissions consultants today to find out about our comprehensive treatment programs for drug and alcohol recovery.

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About the Author

Landmark Recovery

Landmark Recovery

Landmark Recovery was founded with a determination to make addiction treatment accessible for all. Through our integrated treatment programs, we've helped thousands of people choose recovery over addiction and get back to life on their own terms. We're on a mission to save one million lives over the next century. We encourage all those struggling with substance use to seek professional help.