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The Science Of Addiction

If you have ever suffered from  drug or alcohol addiction, you know that it feels like your drug or alcohol cravings are controlling you. Drugs and alcohol affect the brain in many different ways physically, but it doesn’t stop there. As a result of these physical alterations, mental and behavioral changes often follow. This is a result of structural and chemical changes in their brain. These chemical and structural changes are why quitting drugs or alcohol is so difficult for people who are addicted, and why most people need the help of professionals in order to stop.




The Science Of Addiction

Addiction as defined by the National Institute on Drug Abuse (NIDA) is a chronic, relapsing brain disorder characterized by compulsive drug seeking and use despite adverse consequences. To break down what a chronic, relapsing brain disorder is:

Chronic – an illness that extends for long periods of time. Addiction is a chronic disease similar to other chronic diseases such as type II diabetes, cancer, and cardiovascular disease.

Relapsing – an illness that comes back after periods of improvement. Addiction can come back after treatment.

Brain disorder – an illness that affects the brain specifically, and causes the brain’s function or size to change.

Recent groundbreaking discoveries about the brain have revolutionized our understanding of compulsive drug and alcohol use, enabling us to respond effectively to the problem. When many people think about addiction, the first thought that comes to mind is often the health problems associated with drug and alcohol abuse. We all know a substance abuse problem can lead to a visible decline in physical appearance, but there is a lot more going on behind the scenes. Along with the physical health repercussions of long-term drug or alcohol abuse, prolonged use of these substances can literally change the functions of your brain. The brain is a complex system of special cells called neurons that communicate with each other through chemicals called neurotransmitters. These communications and connections control your thoughts and behaviors. Addiction occurs when drugs or alcohol alter the levels of neurotransmitters in the brain and the person comes to crave these changes.

The human brain is the most complex organ in the body. This three-pound mass of gray and white matter sits at the center of all human activity—you need it to ride a bike, to eat a meal, to breathe, to create, and to enjoy everyday activities. To send a message in the brain, a neuron releases a neurotransmitter into the gap (or synapse) between it and the next cell. The neurotransmitter crosses the synapse and attaches to receptors on the receiving neuron, like a puzzle piece locking into another. Drugs and Alcohol interfere with the way neurons send, receive, and process signals via neurotransmitters. Drugs and Alcohol can cause neurochemical and molecular changes in the brain and alter the areas of the brain that are vital for life-sustaining functions. Our brains are wired to increase the odds that we will repeat pleasurable activities. The neurotransmitter dopamine is central to this. Just as drugs produce intense euphoria, they also produce much larger surges of dopamine, powerfully reinforcing the connection between consumption of the drug, the resulting pleasure, and all the external cues linked to the experience. Large surges of dopamine "teach" the brain to seek drugs or alcohol at the expense of other, healthier goals and activities. This dopamine signal causes changes in neural connectivity that make it easier to repeat the activity again and again without thinking about it, leading to the formation of habits. To understand what is happening in the brain, we must break down addiction into a cycle of three stages that affect three specific areas of the brain. This helps us understand the compulsive and impulsive actions a person with a substance use disorder takes. The three stages are binge/intoxication, withdrawal/negative affect, preoccupation/anticipation.

Binge and Intoxication Phase

Long-term use of drugs or alcohol activates an area of the brain called the basal ganglia, or the reward system. This reward system causes a rapid release of dopamine, a neurotransmitter that produces positive effects. The rapid dopamine release creates the euphoric high that users experience when using drugs or alcohol. This process also changes the chemical balance of your brain affecting areas such as mood regulation, stress sensitivity, and decision making.

Withdrawal and Negative Affect Phase

Chronic use of a substance leads to the reward system correcting the balance of reward chemicals released by reducing the amount of dopamine naturally produced in the brain. After long-term use the brain requires a greater amount to feel high again and other activities feel less rewarding without the substance. This reduction of naturally produced dopamine in the brain  leads to addiction.

Preoccupation and Anticipation

The third stage preoccupation/anticipation is caused from changes in brain’s chemical levels and the continued use of the substance. The user begins to crave the substances and is at a much higher risk for relapse even after a period of abstinence. The brain begins to experience  conditioned reinforcement and associates the reward with certain behaviors, people, and places that led to them getting the high. This association alters the brain’s decision-making area, and overrides healthy decision-making processes. When a person’s brain is exposed to this environment, executive function areas can override normal brain function and healthy decisions in order to seek out the drug again to achieve the high.

Areas Of The Brain Effected By Drugs And Alcohol 


The Basal Ganglia, the cortico-basal ganglia system is a complex network involved in motivation and reward. It plays a vital role in positive forms of motivation, including the activities like eating, socializing, and sex, and are also involved in the formation of habits and routines. It's sometimes called the brain's "reward circuit." The basal ganglia is made of 2 systems which regulate motivation to show reward-seeking and misery-fleeing behavior. The reward-seeking mechanism is considered the essential mechanism behind addiction.

The Extended Amygdala plays a role in stressful feelings like anxiety, irritability, and unease, which are present during the withdrawal after the drug high fades and is what  motivates the person to seek to use the drug again. This circuit becomes increasingly sensitive with increased drug and alcohol use.

The Prefrontal Cortex powers the ability to think, plan, solve problems, make decisions, and exert self-control over impulses. The prefrontal cortex is responsible for your self-control and behavioral monitoring: response inhibition, behavioral coordination, conflict and error prediction, detection and resolution. When damaged it can cause Impulsivity, compulsiveness, risk taking and impaired self-monitoring.


The Role Of Genetics In Drug And Alcohol Addiction

Scientists estimate that genetic factors, including environmental effects on these genes, account for between 40 and 60 percent of a person's vulnerability to addiction. Recent research has begun to uncover which genes make a person more vulnerable to addiction, which genes protect a person against addiction, and how one's genes and environment interact. Greater evidence is also building that individuals with mental disorders have a much greater risk of drug abuse and addiction than the general population. Drug and Alcohol addiction shares many features with other chronic illnesses—one of which is heritability, meaning a tendency to run in families. Scientists are now studying how our genes play a vital role in making a person vulnerable to drug addiction. By mapping DNA sequences in addiction patients, researchers have been able to isolate gene sequences that indicate a higher risk of becoming addicted to drugs. These gene sequences contain the instructions for producing specific proteins, which perform most of a body's life functions. The way these proteins function, or don't function, can indicate how vulnerable a person is to drug addiction.

Through research using mice scientist have been able to discover many addiction-related genes, plus a deeper understanding of how the genes function.  A study performed by scientist at the Howard Hughes Medical Institute at Duke University Medical Center were able to identify a specific protein—PSD-95— has a relationship both to drug addiction and to learning and memory. An additional study found that almost every known drug of abuse—including cocaine, opiates, and amphetamines—works through a brain protein known as DARPP-32. DARPP-32 is involved as a go-between in the actions of virtually all neurotransmitters (chemical brain messengers) in all parts of the brain. When DARPP-32 was removed from the brains of mice, the mice no longer responded to drugs of abuse. However no single factor can predict who will become addicted to drugs. Addiction is influenced by a tangle of factors involving one's genes, environment, and age of first use.

Are you or someone you know struggling with Drugs or Alcohol

Are you or some one you know struggling with Drug or Alcohol Addition?
Contact one of our drug and alcohol treatment staff members today to learn more.