Ever wonder how exactly people become addicted to harmful substances? It can be easy to judge from the outside. People who have never experienced substance abuse themselves tend to have misconceptions on what really goes on in an addicted person’s brain. Science, for many years, did not play a role in defining and understanding addiction but research has proven there are biological connections.

The word “addiction” is derived from the Latin term for “bound to” or “enslaved by, because addiction makes regular people slaves to their drug of choice. But it wasn’t always seen that way. In fact, in the 1930s, doctors and medical professionals thought addiction was the result of amoral and deviant personalities. In their eyes, the people who became addicted to substances simply lacked the moral judgment and willpower to quit. The solution at the time was to punish the users or attempt to force them to break their habit. But luckily, after years of research, the scientific community has now seen the effects that drugs have on the actual chemistry of the brain. It was a relief, but at the same time, it became clear that addiction could take hold upon anyone and everyone — no one was safe. 

Unfortunately, the idea that addiction is caused by a moral failing and that those with addiction should “just quit”, as if it were that easy. Many also believe that addiction is a choice, and those who suffer from substance abuse are simply choosing to continue to use a substance or engage in an activity because they want to. In this article, we will walk through the process of becoming addicted, and explain the science behind how addiction manifests in our brains. 

Addiction is more than just substance abuse

Research has also showed that substances weren’t the only thing that could cause addiction. People could also become addicted to things like shopping, gambling, pornography, etc, which would create a shift in the chemical balance of the brain despite not contributing any sort of chemicals to the body (Harvard Health Publishing). This shows that it’s not necessarily the chemicals within substances themselves that cause addiction, but rather the way the brain’s reward center is stimulated.

How the brain works


  • Dopamine: One of the types of neurotransmitters (NT) that helps communicate information between neurons. This NT helps regulate movement, attention, learning, and emotional responses. It also plays a big role in our drive to seek pleasure and satisfaction as part of the brain’s reward system, which is a big reason why it plays a critical role in the development of addiction.
  • Glutamate: An excitatory neurotransmitter that plays a role in learning and memory.
  •  Neurons: Can also be referred to as a nerve cell. This is an electrically excitable cell that transmits and receives information via a network of electrical and chemical signals. It is one of the basic elements of the nervous system and plays a pivotal role in the brain’s communication with the body.
  • Neurotransmitter: A chemical substance released at the end of a nerve fiber after receiving communication from the neural network. It then diffuses across the synapse to communicate or cause a reaction to another nerve fiber, muscle fiber, or other structure.
  • Nucleus accumbens: Part of the brain that neurons project to during the addiction process, which increases dopamine levels. 
  • Peripheral nervous system (PNS): This system contains all of the nerves that are outside of the central nervous system (CNS). Its primary role is to connect the CNS to the organs, limbs, and skin, which means this system reaches all outermost parts of the body. The PNS allows the brain and spinal cord to receive and send information to other areas of the body, allowing us to respond to stimuli around us.
  • Prefrontal cortex: This part of the brain plays a big role in planning complex cognitive behavior, personality expression, decision making, etc. 
  • Synapse: A structure that allows a neuron to transmit an electrical or chemical signal to another neuron.
  • Transporters: Recycle neurons by returning them to the neuron that they originated from. 

Our brain is responsible for all of our daily functioning, from speaking to eating, and even breathing. Some of these processes are automated (such as breathing and staying awake) and others, like having conversations, making decisions, etc are the result of a number of processes happening altogether to spur your body into action. The brain is made up of billions of cells called neurons, which are organized into circuits and networks that allow the brain to send signals. These neurons communicate by sending signals to each other by “firing” off information through the network to different parts of the brain, as well as the spinal cord, nerves, and peripheral nervous system

When sending a message, a neuron releases what is called a neurotransmitter into the synapse (AKA the gap between the original neuron and the next cell). The neurotransmitter crosses the synapse and connects to receptors on the next neuron which stimulates the receiving cell. Transporters then recycle the neurotransmitters by returning them to the neuron that originally released them, and this closes the signal between neurons. 

The science behind addiction

Drugs disrupt the process described above by changing the way neurons send, receive, and process signals via neurotransmitters. Addictive drugs and certain activities are so pleasurable to us because they flood the brain’s reward system with dopamine in a short amount of time, something that we cannot get via the natural process of the neurons. Meanwhile, the hippocampus stores this information as pleasurable memories and the amygdala creates a conditioned response to certain stimuli. 

Recent research suggests that dopamine not only contributes to the pleasure one feels when under the influence of a substance, but it also affects learning and memory, which play key roles in the transition from simply enjoying something to actually being addicted to it. The most widely accepted current theory about how addiction works, states that dopamine interacts with another neurotransmitter, glutamate, to take over the brain’s reward-related learning system. Addictive substances stimulate that circuit and overload it, which repeats every time the person uses. This causes nerve cells in the nucleus accumbens and the prefrontal cortex (the area of the brain responsible for planning and executing actions) to transform liking something into wanting it. This, of course, is what leads to the intense desire to chase after and continue using whatever originally caused this connection to be made in our brains, manifesting as what we know as addiction. 

How addiction persists

After some time of using the substance, the effects become less pleasurable to the user. However, because the brain’s chemistry is now altered, the person continues to seek out the substance because of the addiction it has created, not necessarily to recreate the initial pleasurable symptoms. It becomes a matter of maintenance, in essence. Addictive drugs can release two to ten times the amount of dopamine that the brain naturally produces, and it does it more efficiently and reliably. However, there is a trade-off to this quick response, and that is that the brain receptors become overwhelmed with this overflow of neurotransmitters. As a response to this overload, the brain simply stops producing a normal amount of dopamine or even begins eliminating dopamine receptors. 

This, of course, causes dopamine to have less impact on the brain’s reward center because the brain becomes numb to it. This is what is referred to as tolerance. Developing tolerance can be dangerous because most substance-addicted people combat tolerance by simply increasing their intake of the drug. In effect, they begin flooding their body with more and more of the substance over time. Perceived tolerance is what causes many people to overdose, especially when they have made an attempt to get clean and then go back to using the drug. This is because they had grown accustomed to taking a large amount, but in the time they were sober, their brain had begun to decrease its tolerance in an attempt to return to normal functioning. So then, if the user misjudges how much of the substance they can handle, they can cause serious harm to themselves or even death when they relapse. 

The science behind recovery 

Because the brain has adapted its functioning to cope with the addiction, the addicted person must go through a period called “detox”. Detoxing requires them to wean off of the addictive substance or activity to “cleanse” the brain and get it back to its regular state of function. Unfortunately, this often leads to some pretty intense and uncomfortable side effects, referred to as withdrawal. Until the brain is able to catch up, withdrawal can be a difficult process to get through, which is why it is highly recommended to go through a medical detox in a treatment center. This way, you will be under 24/7 watch from healthcare professionals that will be able to make the withdrawal process as comfortable and safe as possible for you. 

While the brain can and does recover when a person detoxes from their drug of choice, it is possible that long-term use can cause permanent damage. And this damage doesn’t just end with your brain. Substance abuse disorder has a negative impact on you, your career, your family, your friends, etc. Unfortunately, because addiction is stored in your brain as memory, the road to recovery can be long, difficult, and full of obstacles. But recovery is possible, and there are a number of effective treatment programs out there that involve self-help strategies, counseling, and rehabilitation. 

Talk to Someone Who’s Been There. Talk to Someone Who Can Help. Scottsdale Recovery Center® holds the highest accreditation (Joint Commission) and is Arizona’s premier rehab facility since 2009. Call 602-346-9142.