“Neuroanatomy and neurochemistry?! And you’re going to link it to an important social issues?! I knew you were a generous man who knows what I need,” you’ll say at the end of this article.
Have you ever heard someone say that addiction is a disease? Have you ever heard someone say that addiction isn’t a disease, but rather, substance abusers merely choose to make themselves sick? Have you ever heard someone defend either of these positions adequately?
Here’s a clip of a debate between Matthew Perry (a famous actor) and Peter Hitchens (a journalist), both of whom have obvious influence on a significantly sized audience. Notice how neither puts forth an objective, valid, scientific fact to support their claims, and that the one person in this discussion who does is Baroness Meacher, to whom little attention is paid.
So, is addiction a “fantasy” and do drug users choose to give up their lives to get high, as Mr. Hitchens so callously puts it? Is it an allergy as Mr. Perry baselessly asserts? Or is it a disease of the brain with an overwhelming amount evidence elucidating its mechanisms as well as its manifestation in the brain, as Baroness Meacher, citing research of genetic and environmental factors, so logically concludes? I hope I haven’t given away the answer. Let’s find out.
Let’s look at what’s going on inside the body of an addict to find out.
First off, there hasn’t been much evidence in support of Dr. William Silkworth’s claim that alcohol dependence results from an allergy. So, I won’t go over that, except to say that I don’t think it’s a credible claim.
In a region called the midbrain, a neurotransmitter called dopamine (DA) is used in intercellular communication. The midbrain is important because two areas within the midbrain, the ventral tegmental area (VTA) and the nucleus accumbens (NAc), process rewards, which can be something such as food or sex. The midbrain transmits the information about the reward via dopaminergic pathways (meaning pathways that communicate by use of DA) to frontal brain regions that, as I know you know, regulate behavior. In a crude sense, the midbrain tells the frontal areas what’s important for survival, the frontal areas store a memory of its importance, the midbrain then says I need it now, and the frontal areas then direct our behavior to go out and get it.
Now, when certain substances, such as cocaine and alcohol are involved, activity in the brain’s reward circuitry surges. How does this happen? Well, some drugs, like opioids, are what we call an agonist of DA, meaning they are structurally similar to DA molecules and thus, have similar effects on the brain. Other drugs, which are not DA agonists may cause signaling cascades in the brain, which will then turn up the DA system. Now, with extra DA in the brain the reward circuits are turned up much higher. What does this mean? Essentially the midbrain, not unlike the first person you probably smoked pot with, says, “this is GOOD.”
A quick note about neurons, and important principle in neuroscience is, when two neurons communicate between each other often, that synapse (the connection between them) becomes much stronger. This is the neural basis for learning. As you practice something, let’s say cheese wheel-chasing, you may, your first time, jump out ahead as quick as you can to catch the cheese. You quickly loose your footing and everyone goes right by you. The next year, your pace yourself slightly, but end up staying in the middle of the hill with the pack and get involved in a pile-up when the person next to you falls, you idiot. The next year, you pace yourself, stay out of the packs, but when you fall 3/4 of the way down the hill, you land hard and can’t get up for a few days. Until at last, you pace yourself, stay out of the packs, figure out which way to fall is best and now you’re the Cheese Roll Champion of Gloucestershire. As all of this occurs, the cheese wheel-chasing circuitry in your brain gets stronger and stronger.
Essentially, when we take drugs that activate our DA system, the continued hyperactivity of our reward system makes the connections between the drug and a biological reward very strong, which explains the difficulty of quitting drugs and relapse after quitting. We are actually being tricked into learning (in a neurobiological sense) that we need them for our survival. This may seems hard to believe, but we can, of course, learn something that isn’t true.
Now that this drug has a firm hold on our goal-directed neurocircuitry, we see it as more and more important, eventually surpassing the things we actually need for survival, causing our addicted brains to use all the money we can get to buy the substance instead of food, if we have to.
So, is it a disease, or a decision? I think it seems clear. It’s both – a disease of our decision making ability. The drug of choice becomes our reason for living and the decision making circuits in the brain are disrupted by the learned importance of the drug.
Something important to remember however, is that many less people than you may think become drug addicts. It is not known, however, what is different about addicts versus non-addicts in terms of susceptibility to addiction, other than certain genetic and environmental factors. For some interesting, useful insight, I highly recommend this interview with neuroscientist Carl Hart.
Many more questions arise: What is it about some people that they do drugs in the first place? Do long, harsh prison sentences, have a positive effect on ending drug use and deterring non-users from drugs, as well as crime in general, as Peter Hitchens suggests to Russell Brand? Does the War on Drugs cause more trouble than it alleviates?
These questions and so many more will be addressed in future posts, so be sure to subscribe, either via email or on WordPress to receive notifications about these posts. Be sure to comment with any questions, corrections, opinions, etc. And feel free to share this with anyone you know who argues about whether drug addiction is real or not, but has never heard of the NAc.
If you’re interested in learning more about the neuroscience of decision making, a new field called neuroeconomics, coursera.org has a great course on the subject, and you don’t need to have a neuro degree to take it.