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The Neuroscience of Addiction…

Updated: Jul 21, 2020

My Recap of Biology of Desire by Mark Lewis.

There are two main areas in the brain that are critical when it comes to addictive behaviors: 1. The striatum: one of its functions is goal-oriented behavior. It makes us pursue goals to get what we want (food, sex, protections, shelters…). It narrows your behavioral scope and focuses your attention on the goal. Basically, it’s in charge of desire.

2. The dorsolateral pre-frontal cortex, which is responsible for judgement, decision making, insight, personality expression… Usually there is a constant conversation between these two parts of the brain, they are very much connected. They have to be connected in order to modulate desire, deciding what is the best way for you to achieve whatever it is that you want to achieve. Both of these systems are fueled by dopamine. Dopamine: dopamine is best known for driving the pleasure-reward seeking loop; however its function is much more complex. Dopamine activates the various systems to bring focus, to narrow attention, to selectively create memory, and to drive desire.

So, the striatum is like a motor. It’s the driving force, pushing you toward the goal that you desire. The pre-frontal cortex is like the steering wheel and the brakes – they enable you to meet the goal in keeping with your personality, value system, social expectations.

When someone suffers from addiction, there is a breakdown in communication between these two regions. When the object of addiction (drugs, alcohol, gambling) is in the person’s consciousness, the pre-frontal cortex takes a back seat and the striatum becomes the primary driver. An otherwise honest teenager will steal money from his grandmother’s purse to buy methamphetamines.

The brain’s structure changes as we learn, from infancy to the present. The brain learns by creating new synaptic connections while at the same time pruning multiple preexisting connections.

Learning is the process of synaptic restructuring. Once a skill is deeply learned, it becomes a habit. Think about riding a bike. When you start, you have to focus intensely on maintaining balance, steering, pedaling. But once you are a proficient rider, you don’t have to think about anything – you just get on your bike and you ride. Riding your bike becomes a habit. This is true for all learned behaviors or skills that become effortless: driving a car, speaking a language, typing on a keyboard. The synaptic connections responsible for the executive functions of riding a bike become cemented. They also become more obvious because other, surrounding connections are pruned away. So, learning is just as much about selective pruning of connections as it is about creating new connections. During adolescence, when skills are created and personality is solidified, up to 30,000 synapses are lost every second throughout the entire cortex. This enables us and our brains to be more efficient -- it’s like creating a well-worn footpath through a grassy lawn. When we compare brain MRIs of people with and without addiction (of any type), we see tremendous signs of pruning in the brains of addicts. The mass of grey matter is visibly reduced, there is an obvious loss of synapses. For many years we thought that this reduction in gray matter in the brains of addicts is a sign that addiction is a disease which literally affects the structure of the brain. Now we’ve come to realize that it is not the substance abuse that creates these structural changes, but rather the repetitive, habitual behavior. The same loss of gray matter is seen in addictions to sex, social media, and food, as well as drugs. The pruning results from the repetition. As the addiction develops, pruning occurs because the brain is becoming super efficient … at getting loaded! ☺ After 40-60 weeks of moving away from the addictive behavior, the surrounding synapses are rebuilt and the addictive neuronal pathway is less stark. Brain change doesn’t mean brain disease. Three key factors keep people in their addiction:

Addiction provides immediate reward -“The Now appeal”- We get trapped in the present:

How am I going to get my fix?


How am I going to pay for it?

There is a phenomenon that psychologist call “delay discounting”. This refers to how people will prefer an immediate reward of lower value over a later reward of higher value, even though there's less overall gain. People who are naturally impulsive are the most prone. Delay discounting has a lot to do with dopamine's short-sightedness. Dopamine enhances the draw of immediate goals, and that's all it cares about. Your higher brain processes are supposed to look out for the future. So the dopamine rush of craving and the urgent pull of present opportunities are intimately linked in your brain. The higher brain processes which look out for the future get overpowered.  

The present moment and getting the fix supersedes all future goals. The future loses its value.

Ego fatigue

Let me share a psychological experiment with you to illustrate this notion of Ego fatigue.

A group of hungry people were put into a room and left alone with two bowls in front of them: a bowl of radishes and a bowl of chocolate-chip cookies. Half were instructed to have some cookies but no radishes; the other half were instructed to eat radishes only—no cookies. After only five minutes, the participants were asked to perform some cognitive tasks that require self-control. Those who'd had to resist temptation (cookies) performed more poorly or quit earlier. The interpretation was that they had "depleted" a resource needed for self-control.

The same social scientists performed another experiment in which participants had to watch a 10-minute video clip that was very emotionally arousing (either humorous or tragic). Half were asked to show no emotion on their faces, and the other half could behave normally. Those who had to suppress their emotions performed more poorly on subsequent tasks. Once again, something had been depleted.

Pure and radical suppression brings ego fatigue very quickly. If 10 minutes of suppressing your feelings saps your cognitive reserves, imagine the impact of suppressing those feelings (deliberately and consciously) all day long, day after day. This is what recovering addicts are facing.

And finally: Personality development.

The addiction often gives the person access or belonging to a community or to an identity (I am a gambler, a smoker, a rebel… an addict). It is difficult to let go of an established identity, even if it is one we do not like.

A few ideas to help people who are stepping out of addiction: - Self Empowerment is KEY! A “Patient” only follows somebody else’s instructions. They rely on these exogenous instructions… It can’t work.

- Strengthen the desire for other goals (similar for depression).

Identify and hold on to specific future goals; Imagine the future in detail.

- Self Forgiveness... I hope you will find this recap useful. Have a wonderful day!

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