The brain-addiction connection : Neurons and neurotransmitters

As I’d mentioned in an earlier post, while many people experiment with, or use, drugs at some point in their lives, only a small percentage (between 10%-15%) develop chronic drug abuse and dependence problems. While some of the specifics of what makes one person more likely to move from recreational use to addiction are still being investigated and hotly debated, we do know quite a lot about what happens in the brain when drug are used.

Before I can go into the specifics of the brain-addiction connection…

We need a little background on the way the brain works:

The neuron

The brain is in essence a very complex network of interconnected fibers (neurons) and their maintenance and support structures. The brain contains about 10,000,000,000,000 (10 trillion) of these cells, and they each make many connections.

The left end of the neuron in the picture on the right is called the dendrite; this is the neuron’s main information receiving hub. The long part extending to the right is called an axon, and it ends in axon terminals that eventually connect to other neurons’ dendrites.

This is the basic way in which everything that happens in the brain is communicated, including our thoughts, feelings, movements, and memories!!! Dendrite to axon, to axon terminals, to dendrites, and back to step 1. How this transmission is achieved within the neuron is not necessary for this discussion; let’s just say that you should eat your bananas and make sure you always have some potassium, sodium, and calcium in your body…

How do the neurons talk to one another?


What is important for us is the way these neurons transfer information across the gap between the axon terminals and their connecting dendrites. This is achieved by chemicals called neurotransmitters. There are quite a few of these, but the main ones we’re going to be concerned with are serotonin, adrenaline, GABA, and dopamine as these are some of the major players in drug addiction (especially dopamine).

When a neuron wants to send a signal to its neighbor, it releases packets of a neurotransmitter (most axon terminals release only one specific neurotransmitter), and these are received by specialized receptors at the dendrites of the receiving neuron. If enough neurotransmitter is released and enough receptors are activated, the signal starts again and the cycle continues…

Neurotrasnmitters and drug use

Most abused drugs disrupt some combination of factors within this mechanism to produce both the intended, and unintended, effects they are known for.

Alright, that’s probably enough to absorb for now, more on what specific drugs do to interrupt this process soon!

How many of you knew about the ways in which drugs affect the brain? Would you mind sharing the things you’ve learned and where you’d learned them?

4 responses to “The brain-addiction connection : Neurons and neurotransmitters”

  1. […] field who has seen life as an addict first hand. One of my personal favorites is his series on addiction and the brain because I am fascinated at how the brain works; especially the effects of meth on your […]

  2. alcohol abuse-much confusing information. Question: does alcohol abuse result in oxygen deprivation to the brain and do brain cells therefore “die”? Q2: what is a “dendrite crystal” and what is the mechanism by which it causes brain injury? can conditions be reversed? thank you.

    • Hi Mike,
      Alcohol abuse doesn’t necessarily kill cells by oxygen deprivation although cell death in the brain can occur due to some of alcohol’s other effects, specifically its disinhibition of neurons which can cause over-excitability and therefore cell death. I’ve never heard of a dendrite crystal but dendrites are the extensions of neurons that help convey and receive messages from other neurons. While cell regeneration does occur in the brain, meaning that new cells will form that will help compensate for ones that were killed due to overconsumption of alcohol, it’s unlikely that damage can actually be reversed meaning some of the loss will likely be close to permanent especially if it is extensive and the individual is of a relatively advanced age.

  3. It seems as if addiction can mean for myself as striving for a greater feeling even if it’s not acheived. Living life as an addiction to whatever you make your own God. Making a sense to an altimate strength for your own weakness. In other words knowing how your brain works is one part but knowing how it decides is a completely different logic to all brain chemistry.

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