January 21, 2011

021 The Mechanism of Addiction

So what’s the deal with drugs? Why do people get addicted? In this video, Leslie talks about how addiction works at the level of the Neurotransmitter.

Wanna know how it works? Curious? Watch the video 😀

Transcript of Today’s Episode

Welcome to another episode of Interactive Biology TV, where we’re making biology fun! My name is Leslie Samuel. In this episode, Episode 21, I’m going to talk a little bit about the mechanism of addiction. Inside this video, I’m first going to answer the question “What is addiction?”, then I’m going to talk about the mechanism of addiction, and lastly, I’m going to look at some specific drugs and how they affect neurotransmitters. So let’s get right into it.

There are 2 definitions of addiction that I want to look at:

  1. Addiction is believing that you need a drug to feel good or function normally.
  2. Addiction is developing a chemical need for a drug.

The second one is the one that I’m going to be talking about. How do you develop a chemical need for a drug which leads to you becoming addicted to that particular drug?

Let’s look at the mechanism for addiction. What usually happens is, when you take a drug, it multiplies the effect of a specific neurotransmitter. Now, we’ve been talking about neurotransmitters, and we saw how that can lead to a signal in post-synaptic cells. You can always go back to previous episodes to look at how that works. What a drug does is it makes the effect of a specific neurotransmitter much stronger, and that can have some significant effects.

One of the effects is that the nervous system starts to slow down the production of the neurotransmitter. What usually happens is there’s an artificial increase in the effect of that neurotransmitter, so the brain is saying, “Wow, there’s too much of that neurotransmitter there.” So the nervous system actually slows down what it would normally produce. This is a neurotransmitter that the body needs, and since the nervous system slows down the production, you become dependent on that substance that you’re taking in order to return back to normal. So the brain is saying, “Whoa, there’s too much of that neurotransmitter out there. Let me stop what I’m doing.” And in order for you to feel normal again, you need to take more of that substance, more of that drug.

So that’s the general mechanism for addiction. Of course, every drug is going to have a different effect, and of course, there are other effects that these drugs have, but right now, we’re just talking about the specific process of addiction.

So let’s look at some specific drugs and the neurotransmitters they affect. Caffeine is one of the most popular drugs. Caffeine affects the neurotransmitter dopamine. Dopamine is known as the feel-good molecule of the nervous system. There’s a reward circuit that responds to pleasurable experiences by releasing this neurotransmitter.

Another drug that has an effect on that same neurotransmitter is cocaine. That also affects dopamine. This results in a really strong dopamine effect, and the brain shuts down the production of dopamine. In order for you to feel good again, you need to take that drug. Of course, cocaine is on a totally different level than caffeine, and of course, it’s going to have many other effects that we’re not going to go into in this video. So when you take these drugs, it’s artificially increasing a neurotransmitter that normally makes you feel good, and you get an intense feeling of pleasure that’s more than normal, and that also can contribute to the addictive effect of these drugs.

Another common drug is nicotine, and that affects the neurotransmitter acetylcholine. We’ve looked at that neurotransmitter, we’ve seen that it’s an excitatory neurotransmitter that causes EPSPs, excitatory post-synaptic potentials. Nicotine has an effect on this neurotransmitter.

Another drug is LSD, and that has an effect on the neurotransmitter serotonin.

So you can see these different drugs are going to have different effects on different neurotransmitters and how the body responds to these neurotransmitters. When the nervous system stops producing or slows down the production of that neurotransmitter, you need to take more of that drug in order to feel normal.

That’s really it for this video. That’s the general overview of how the process of addiction works. If you have any questions, as usual, go ahead and leave your questions below in the comments section. I’ll be happy to answer your questions, and maybe even make a video to answer your specific question. That’s it for this video, and I’ll see you in the next one.

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