Perhaps I should put a special category up for "things I like to blog about". Or maybe just 'basics'.
Sci's been a little out of her bloggin' groove lately, feelin' her stuff is not up to snuff. But with THIS, Sci will get her groove back. And she will get it back with pictures. Pictures that are drawn in powerpoint so they don't make your eyes bleed. I care.
So what is the opponent-process theory? The opponent-process theory (hereafter called the OP Theory) is one of the current theories we are using to understand addiction. Because, to be honest, we don't really understand it. Oh sure, we know about initial rewarding effects, we know about withdrawal, we know about tolerance. But do we really KNOW what it is that makes people walk away from their families and homes and jobs and sell themselves for their next hit? A next hit that, oftentimes, they HATE and need at the same time? ...nope. Still working on that.
But one of the theories out there to explain drug addiction and how it may work is the OP Theory.
Postulated in 1974 by Solomon, the OP Theory is actually one of motivation. The idea is that hedonic states, the ones that feel good, are modulated by mechanisms that reduce the intensity of the state. So euphoria might be countered by depression, for example. Unfortunately, the more positive feelings you feel, the more you become tolerant to them. And the more your central nervous system will seek to counter them with negative feelings. In the language of addiction, this corresponds roughly to drug affect and withdrawal states.
And though it sounds complicated (and reading any review of it in science-ese, you'd think it was complicated), all you need is a picture in your head. The picture is this:
So what are you looking at here? The yellow arrow pointing up is going to represent positive drug effects: euphoria, energy, less-anxiety, pain relief, whatevs. The red arrow pointing down is negative drug effects: paranoia, nausea, anxiety, etc. And the two opposing loops are measures of relative drug effect.
The idea is this: every drug you take will elicit both positive and negative effects in your body. The positive effects are things like, say euphoric mood, while the negative effects are things like headache, nausea, depression, things like that. These positive and negative effects that you experience are the result of changes in the underlying neurobiology of your brain. So the original acute effects of a drug are opposed by your own neurobiology, as your brain strives to bring itself back toward homeostasis.
So, the first time you take a drug, it might look like this:
The drug has pretty major positive effects at first, with reward neurons firing on all cylinders. The drug completely overwhelms the pleasure circuits, and the brain can't muster enough negative effects of come back to homeostasis. The result: that feels REALLY GOOD.
Of course, this effect doesn't last. As you take the drug more and more, you begin to develop tolerance. The key is that tolerance tends to develop to the positive effects. The OP Theory states that it's not that your body and brain are tolerant to the positive effects, rather, they are sensitizing to the negative effects. Because of this, your perception of the positive effects become blunted. So over time, you start to see something like this:
The positive effects of the drug remain the same, while the negative ones increase. So now your perceiving drug effect looks more like this:
Yeah, looks like that doesn't feel as great. And this is more pernicious than it appears.
First of all, you're going to have to take more drug to get the same initial euphoric effects you had before, because it will take more drug to overcome the negative effects.
Secondly, these negative effects tend to last LONGER than the positive effects of the drug. This is often the result of altered neurobiology. Your body is used to having the drug on board, and certain kinds of signals will get stronger, trying to be heard over the presence of the drug. As your body gets used to the presence drug, it comes to a new state of normalcy. For example, a person without a drug addiction might look like this at the baseline state:
No more positive than negative. Feels like normalcy.
An addict, on the other hand, might look like this:
For example, alcohol. It's pretty well known that alcohol is a potent anxiolytic (I would imagine that if people didn't have alcohol to relieve their anxiety, a good portion of the populace wouldn't get laid at all). Unfortunately, the more alcohol you drink, the more your baseline levels of anxiety increase, especially if you were already pretty anxious to begin with. And those who are pretty anxious to begin with...tend to need a few drinks to relax. But when they stop drinking, the anxiety remains, and the alcohol withdrawal will actually make that anxiety STRONGER, driving an alcoholic toward relapse.
So your positive effects aren't as great, and you need more drug to get high. Not only that, the negative effects of the drug and the withdrawal syndrome stick around, driving you to seek out the drug again, just to overcome your new negative state of homeostasis.
So basically, the idea of the OP Theory is one of limited reward. You don't want to be feeling the massive effects of reward all the time, you need it to be balanced out by other things, like discomfort. This keeps you aware of the world around you and able to respond, instead of blissed out. So sex, for instance, will feel good, but not THAT good.
Drugs, on the other hand, hijack this system. They feel TOO good. Your body can't achieve homeostasis. It has to drive negative signalling up a notch to counteract the drug. But the drug goes away, and the negative feeling stays. And the next things you know, you're just STRESSED, you know, and all you really need is a drink...
There's only one issues with the OP Theory: it's probably wrong. But it's wrong in the way that most of the theories we have about understanding the brain, and particularly about understanding things like motivation and reward, are wrong. It may not be entirely wrong, it may just be incomplete.
The important thing is, it's not perfect. There are some drugs that have relatively limited negative effects, increases in which do not account for the tolerance to the positive effects (like cocaine). There are some drugs which have some pretty major negative effects (like alcohol), which don't seem to have enough positive effects to make them appealing. Yet they are.
So, until we come up with a new theory, or find explanations for way to make exceptions fit, the OP Theory is a flawed one. But isn't every theory a flawed theory? And it's what we've got to go on right now. Give us a few years, and we'll give you the next theory, until we finally get it right.