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The Neuroscience of Addictions

Updated: Apr 19

Neuroscientist and former addict Marc Lewis shares the interesting things that happens in the brains of addicts and recovered addicts. How does the brain change in response to addictions? Which parts of the brain are affected? Can the brain ever be the same as it was prior to the addiction? Read more to learn the answers to these questions and more.

A light bulb with a brain inside and the text what happens in the brain?

Changes in the Brain

During a longer period of addiction the brain goes through changes. Psychical changes occurs in parts of the brain critical for judgement, learning, memory, decision-making and behavior control.

Three different parts of the brain are connected to addictions:

  1. Prefrontal cortex. This part is like the bridge of the ship. It's responsible for judgement and decision-making. Our behavior is derived from this part.

  2. Striatum. This is the engine of the ship. Striatum creates motivation that makes us want to achieve goals.

  3. Midbrain. The fuel to the engine. The midbrain regulates dopamine that gives the striatum energy to create goals.

So how are all these parts connected? In addictions, dopamine is sent from the midbrain to the striatum. The striatum becomes activated and we get focused on the goal, which could be drugs, alcohol etc. The prefrontal cortex is responsible to regulate the impulses and signals received from the striatum. Naturally there's a balance between the prefrontal cortex and the striatum. However, after a long period of addiction, the connections between these areas grows weaker. Brain imaging studies shows that the gray matter volume reduces in these regions. This does not mean that brain cells are lost, but the synapses that connects these parts grows smaller in numbers. The connections are not entirely gone. But when the addiction

is triggered there is a disconnection.

Reinterpreting the Data

The brain is a flexible organ. It is constantly in development.

The brain changes drastically as we are growing up. Young children have an overabundance of synapses in their brains. These synapses are helpful for learning new things and understanding the world. However, the synapses gradually decreases as we age. Necessary synapses remain, while unimportant ones disappear.

The development- and learning processes are nearly exactly the same. Both involve synaptic growth and pruning. Synaptic growth occurs with new experiences, situations, knowledge and skills. We develop an increase in synapses that helps us learn what we need. However, we do not need all of these synapses. Therefore, after some time, there is a synaptic pruning. The most important connections become entrenched while others fade away.

The process is almost the same in an addiction. The addiction turns into a habit where the synapses that are not crucial in feeding the addiction disappears. Similarly to the development/learning- processes there occurs a synaptic pruning.

Even though some synapses do disappear, this does not mean that we cannot create more synapses. Once a person has recovered from an addiction, after some time, more synapses are created. There is an increase in gray matter volume in the same area it was lost in before the addiction started. The synapses will not, however, appear in exactly the same place as before. The brain is always changing. However, the new synapses shows up in parts of the brain that controls impulses and self-regulating behavior. Precisely the areas addicts need to stay clean. After a few years, the gray matter volume has even increased above the curve for the non-addictive baseline.

Addiction as a Skill

New skills and experiences always change the brain. A person developing an addiction is similar to someone learning and mastering a skill. The addiction becomes a ritualized behavior that is repeated day after day after day, without the need for further complex thoughts.

What happens in the brain is similar to what happens in other skills and experiences.

For example:

  • Falling in love. When you fall in love, a significant amount of dopamine is sent to the striatum, making you goal oriented. Like an addiction, the need to be near the other person becomes like a repeated behavior. A constant craving of your love interest.

  • Mindfulness and meditation. When we are meditating we learn how to turn the attention away from ourselves. We become less focused on our ego's.

  • Behavioral addictions. For example: binge eating, shopping, gaming, porn, internet etc. Studies of internet addictions shows that the gray matter volume decreases in almost exactly the same areas as in substance abuses.

  • Psychotherapy. For example: cognitive behavioral therapy. If the therapy is successful, the structures in the brain actually change, making the brain function better.

So the proposition that substances are unique in how they affect the brain is simply wrong.


Why is it so Difficult to Quit?

There are three concepts that contributes to making it hard to give up an addiction.

  1. A self-perpetuating feedback cycle

  2. Getting stuck in the ”Now appeal”

  3. Ego fatigue: loss of self-control

1. A self-perpetuating Feedback Cycle

An addiction is like a cycle, going in circles, keeping itself alive. It starts when you get a trigger and the brain becomes activated. Images are created in the back of the brain and the midbrain sends dopamine to the striatum. With energy from the dopamine, the striatum creates a desire and you begin getting cravings. Thereafter, the striatum sends messages to the midbrain that it wants more dopamine and you get even more cravings. The cravings will eventually become so strong that the prefrontal cortex becomes activated. You start to plan: How can I satisfy these cravings? Finally, signals are sent to the motor cortex and it does what you want it to do. This can be: to take drugs, drink alcohol etc. Once it is all over, you often feel feelings such as loss, shame and regret.

This cycle has three effects. First: relief/pleasure. Then: learning. And finally: loss. Together, they contribute to repetition of the cycle.

2. ”Now appeal” or delayed discounting

This phenomenon can be exemplified with the famous marshmallow experiment. Children, around 3 years in age, was given a marshmallow and was told that if they waited a couple of minutes they could get two marshmallows. While some children had the patience to wait, others found it hard to resist the temptation and ate the marshmallow before the time was up.

This effect is called delayed discounting. We often overvalue the immediate rewards while overlooking the long term consequences. This is built into the dopamine-system. We like to reach for the lowest hanging fruit.

When we are getting close to a reward, our evaluation of that reward increases exponentially. We tend to follow the immediate goal because, at the moment, it is worth more than our potential future happiness. The immediate goal has such a great hold on us that it makes us forget the imagined future.

3. Ego fatigue

In a study, a group of test subjects were told not to eat for 8 hours. When they came to the lab they were hungry and was presented with two bowls. One filled with cookies. The other with radishes. The group was split in half. One half was told they could eat as many radishes they wanted but no cookies. The other half could eat as many cookies they wanted but no radishes. After around 10/15 minutes both groups did a set of cognitive tests. The results showed that the group that was not allowed to eat the cookies performed worse than the ones who did. The first group had to repress their impulses to eat the cookies. After some time of impulse control they became fatigued and performed worse in the cognitive tests.

This study illustrates just how difficult and tiresome it is to repress your impulses for a long period of time. A lot of addicts have to repress their impulses for days, weeks, months, even years. It is especially difficult for alcoholics and nicotine addicts, because there are triggers everywhere.

There is always hope.

The truth is that most people actually quit

The time frame is different for each substance, but there often comes a point in the addiction where the addict becomes extremely motivated to quit. Addiction is often defined as a disease, but this definition can be harmful. Statistics from rehab centers that build their treatments on the disease model has a high percentage of relapse. The disease model might help to reduce the stigma around addictions, however, it can become a safety blanket for addicts. Saying: "I can't help my addiction because I'm sick.

The rehab centers often combine the disease model with the 12 step program. What both these methods have in common is the idea that addiction is a fundamental flaw in a person. That it is chronic and something that you need to fight against all your life.

How can we help addicts?

  • Make them feel empowered to quit.

  • Goals and motivation are important. Help them formulate new goals. However, it is not to be forced. The motivation has to come from the inside.

  • Help them imagine their future. Break free from the "now appeal" that disconnects the past from the future.

  • Suggest that they can look at their lives like a movie. The past, the present and the future all in one. Where have you come from and where are you going?

Treatment works by connecting:

  • Empowerement to the future self

  • The stratium to the prefrontal cortex

  • The self to the social world

Psychological tools can also be valuable assets. Different types of therapy such as: Cbt, Dbt, Psychodynamic therapy etc. Mindfulness and meditation can also help, together with the support of a social network.

Treatment should always be based on the individuals needs.

It is important to remember that the brain never stops developing. And- the addiction can be broken!

See the lecture below to learn more

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