Evolution, Addiction, and the Brain
Photo by David Matos
Originally Posted On: https://medium.com/@drchrisjohnston/evolution-addiction-and-the-brain-75096cbd6ff9
Have you heard of evolutionary psychobiology?
You don’t have to answer.
But I will.
Before last week, I admit — I’d never heard of it (either). I know what those two words mean, of course, and if push came to shove, I bet I could tell you what it is. I’ll spare you my educated guesses, though, and give you a definition straight from an evolutionary psychobiologist:
“Evolutionary psychobiology is a scientific perspective that involves the analyses of inherent neurobiological mechanisms that mediate the behavior of an organism; in other words, the ‘hows and whys’ of adaptive behavioral responses to environmental pressures.”
Those of you who’ve read my articles here — “Early Life Adversity and Opioid Addiction”, “The Benefits of Recovery, Explained (With Numbers) ”, and “What is Recovery? Abstinence, Sobriety, or Something Completely Different” — know that I’m a physician who works in addiction and recovery. You also know I spend a lot of time reading articles I think will help my patients, because I tend to meet them at low points in their lives, and my job is to help them find a way to higher ground. In most cases — by their own definition — that means I help them build a life not dominated by drug seeking behavior, drug cravings, or the painful emotions related to addiction.
What does evolutionary psychobiology have to do with all that?
Let’s take a look at the last phrase in the definition above for a clue:
“Evolutionary psychobiology is…the ‘hows and whys’ of adaptive behavioral responses to environmental pressures.”
When I read that phrase closely, I realized that my work as an addiction specialist intersects with the work of evolutionary psychobiologists — and that was news to me.
Addiction and Survival: Coping to Live
One thing I tell many of my patients is that their addiction — in the very early stages — likely developed as a coping mechanism to protect them from painful emotions or as a practical strategy to enable them to handle extremely difficult life circumstances. In other words, their addiction developed in order to help them survive.
In still other words, their addiction can be seen as “an adaptive behavioral response to environmental pressure.”
Are you having the same lightbulb moment I did?
I think so.
If not, stick with me.
I found this new phrase — evolutionary psychobiology — while reading a paper called “Evolutionary and Neuropsychological Perspectives on Addictive Behaviors and Addictive Substances: Relevance to the Food Addiction Construct.” The link above, preceding the definition, will take you to that article, if you have the time and inclination to read the whole thing.
What interested me most was the neuropsychological element of the paper. It implied they’d identified an underlying neurobiological mechanism that evolved at some point during the history of our species, and that the presence of that mechanism makes humans uniquely vulnerable to addiction.
The study authors presented a compelling case.
They outline evolutionary explanations — meaning they elucidate how these things confer a survival advantage — for our preference for the following behaviors:
· Gambling (i.e. predicting outcomes and taking risks)
· Ingesting alcohol/ethanol
· Ingesting nicotine
· Eating plants rich in alkaloids, including the opium poppy
Each of these behaviors, when they developed, helped humans survive. That’s why the human brain is wired to participate in these behaviors or seek these specific substances. The fact that all these behaviors are reinforced by our internal reward system drives the point home. Our preference for these behaviors developed to point us toward those behaviors because those behaviors helped us survive.
All that makes perfect sense and is consonant with everything I know about addiction.
And that’s where the paper got even more interesting.
When Reward Goes Wrong
I’ll simplify the whole evolution angle, here, using food as an example.
We need food to survive. Therefore, our brains created mechanisms that cause us to seek food. But that’s not all. Our brains also created mechanisms that make us feel really, really good after we eat food — that’s the reward system. It’s a two-part process: we’re driven to seek, and when we succeed at finding, we’re rewarded by feeling great. So not only did we evolve a drive to seek the things that help us survive, we evolved a system that gives us a prize when we accomplish tasks that help us survive: that prize is pleasure.
The study authors propose that what happens with addiction — in part, at least — is that those foundational, ancient, evolutionary drives and rewards no longer match our current needs. And I’m not talking about food anymore, obviously: I’m talking about things like gambling, ingesting alcohol and nicotine, and consuming alkaloid chemicals derived from the opium poppy. Here’s how the authors of the study put it:
“It can be argued therefore that we evolved a genetically determined predisposition for drug use. It has been the purification of psychotropic plant ingredients, however, and their ready availability in many societies globally, that have led to an increased propensity for problem drug use. The risk for dependence and abuse is consequently an environmentally induced fallout of our once-adaptive preferences for these natural substances.”
That’s a fancy way of saying that once upon a time, seeking the pleasure associated with alcohol and opioids, among other things, helped us survive. But now that those chemicals are fairly easy to get, available almost anywhere, and enter our bodies at much greater concentrations and potencies than ever before, our genetic predisposition backfires. Behaviors that were once advantageous for survival are now the opposite: given free access to the chemicals we seek, these behaviors are now disadvantageous.
Connecting the Dots
Here’s how I can use this information to help my patients — and here’s how I’ll tie the various threads of this article together.
Remember, towards the beginning of this piece, when I said I tell my patients they likely developed their addiction in order to survive? What I didn’t say was that, at the time, their addiction was a positive survival adaptation. It helped them live when they needed it. When they come to me, however, the situation has changed: the addiction no longer helps, and they no longer need it to survive. In fact, it now does the opposite. It contributes to their deterioration and may lead to their death.
Did the lightbulb go off?
What my patients experience can be viewed as a microcosm of what humans — over the millennia — have experienced in the macrocosm. Drives that once helped humans survive are no longer adaptive, but rather, maladaptive. Behaviors that once helped my patients survive are no longer adaptive, but rather, maladaptive. Our ancient ancestors ate the poppy: it helped. My patients’ earlier selves used drugs: they helped.
But that’s in the past.
Now I have an epic analogy — based in evolutionary psychobiology — to help explain to my patients the concept that what once developed as a positive survival mechanism no longer serves that purpose. I can use it to emphasize that it’s time to develop new survival mechanisms that serve them today, and abandon those from the past that no longer serve them.
And it’s not really an analogy, is it: these mechanisms are present in our brains right now. Knowing that, and understanding how they work, can help us all understand — and move past — our deep, organic, neurochemical predisposition to addiction.
Christopher Johnston, MD, ABPM-ADM, is the Chief Medical Officer for Pinnacle Treatment Centers, a leading drug and alcohol addiction treatment provider. Dr. Johnston has practiced addiction medicine for the past 15 years, initially in a family practice setting primarily for opioid dependent patients and for the past eight years at Pinnacle working with individuals in residential and outpatient programs with all types of substance use disorders. He is double boarded in both Addiction Medicine and Family Medicine. Dr. Johnston attended UMDNJ — New Jersey Medical School in Newark and completed his residency at Virtua Health in Camden County, NJ, where he was in private practice for 25 years.