The Neurology of Addiction

Addiction is all about your brain. Although the point at which someone becomes “addicted” to drugs is hard to define, the development of tolerance and the presence of withdrawal symptoms (when the drug isn’t taken) are two of the most reliable markers for a physical addiction. The root of these phenomena is the brain, and specifically how it adapts to the effects of the specific substance. Your brain becomes addicted because it’s trying to protect its ordinary functioning, and understanding this process gives you a better understanding of addiction as a whole. After all, the things going on in the brain shape our behavior.

Understanding Ordinary Brain Functioning

The first step towards understanding the neurology of addiction is to understand how the brain functions under ordinary circumstances. It’s made up of several different regions that control different areas of functioning, so the brain stem keeps your critical functions (like breathing) going and the cerebral cortex processes sensory information and controls thinking and decision-making. Drugs primarily affect the limbic system, which is our built-in reward system.

You need your reward system to encourage you to do the things you absolutely must do. It’s activated when you eat, for example, to make you feel pleasure when you take in food and therefore encourage you to do it again. To create this feeling of pleasure, the brain releases a neurotransmitter – such as dopamine – which is a chemical messenger. It travels between neurons (nerve cells in the brain), being released by one and attaching to a “receptor” on the other. The neurotransmitter is like a jigsaw piece, which only fits into specific slots. When this connection is active, you feel a sensation of pleasure, and then it’s taken back to the original neuron to shut off the signal.

How Drugs Impact Normal Functioning

Drugs cause intense effects in two different ways. They either masquerade as a natural neurotransmitter or they trigger the excessive release of a neurotransmitter. Drugs like heroin and marijuana – which are similar to natural neurotransmitters – can fit into the receptor slot and send abnormal messages. Other drugs such as cocaine trick the neurons into flooding the brain with dopamine (or other neurotransmitters) in far greater quantities than would occur naturally, which massively amplifies their effect.

Dopamine is the neurotransmitter most commonly affected by drugs. It’s an important part of the reward system, and it’s therefore linked to many important areas, such as pleasure, motivation, emotion and cognition. Drugs give your brain a reward, and it isn’t a meager one either, it’s the same as you get for things like food and sex, which are integral to our existence. This is made even worse by the fact that drugs release dopamine in anything between two and ten times the quantity of natural activities. When your brain realizes how much it gets rewarded for taking drugs, the motivation to use becomes greater than the motivation to eat or socialize because the reward is greater.

Where Does Addiction Come Into it?

Your brain is primarily concerned with protecting your mental functioning. Dopamine rewards are great for the brain, but having such an abundance flowing through it can cause some additional problems. For example, cognition is linked to dopamine, so if you’re put in a life-or-death situation that requires quick thinking, a drug user will be at greater risk of death. The brain has to look after itself, so it adapts to the chemical injection if it’s repeated often enough.

To reduce the disorientating volume of the dopamine signal, it takes away some of the receptors and doesn’t make as much of the neurotransmitter itself. It knows it should expect another flood at some point, so it basically prepares itself by closing off entry points and not contributing to the surge. At this point, if the chemical is added again there aren’t as many receptors for it to bind to, so the overall euphoria produced by the drug is reduced. This is the phenomenon of tolerance, a major marker for addiction.

As drug use continues, your brain knows that it doesn’t have to worry about activating its pleasure centers with its own dopamine (which explains why addicts often don’t experience as much happiness from ordinary activities, and rely on the drug to feel “normal,” let alone happy). It basically gets lazy, and drives you towards the quick fix of drugs. If you don’t take them, you’re missing some components of ordinary functioning. You have reduced dopamine production and fewer receptors to receive it, so you start to feel awful.

Instead of going through the process of restructuring itself again, the brain pushes you to take more and more of the drug. It’s like a stand off, with your brain waiting for you to crack and give it the chemical it wants and you waiting for your brain to stop craving and go back to normal. This is the process of withdrawal, and it usually comes with symptoms that are the opposite of the drug’s effects. For example, heroin is a powerful painkiller, so heroin withdrawal often results in a lot of pain.

The brain really just wants to protect your functioning, but if you keep taking the drug your brain continues to adapt, until you are absolutely reliant on it. The more changes your brain makes to compensate for your use, the less it wants to change back. This reluctance means that getting clean is really difficult. You need to remember that your brain changed once and it can change again. It might never go back to completely ordinary functioning, but it usually comes pretty close if you abstain for long enough. Plus, as your brain starts to change it’ll get easier and easier to stay clean.