I used to think addiction was caused by screwy molecules in the brain, and would be cured by neuroscience. I began learning about how the brain works after I ended up in treatment for drug addiction in the mid-1980s, when hopes for neuroscientific cures were as overblown as the hairstyles.
Like many at the time, I envisioned the brain as executive director of an epic drama – solely responsible for the total picture of what I did, felt and thought. My specific purpose in getting a doctorate in behavioural neuroscience was to discover the neural explanation for my irrational choices around mind-altering chemicals. What was the faulty neural switch that swept away heartfelt promises or strongly held convictions in response to practically every opportunity to twist reality? I made increasingly risky and harebrained decisions, as the possibility of transient bliss in a shot of cocaine, a belly full of booze or a head in the (cannabis) clouds came to outweigh my obligations or common sense. Final exams, “last chances” at work, or loved ones’ funerals, for example, didn’t stand a chance compared to hitching myself to whatever intoxicating ride I could catch. By the time I hit bottom, the choice between facing stark reality or using drugs to escape was no choice at all: cortical regulation had completely given way to subcortical impulses and habits.
Globally 35 million people are estimated to suffer from drug use disorders. The causes of this public health disaster are complicated, but it is widely accepted that about half of the contribution comes from inherited risk, and the rest an unfortunate confluence of environmental factors interacting with that biologic vulnerability.
Either way, addiction has been widely seen as an individual dilemma driven by a derelict nervous system. The sanguine view that the problem with people like me furnishes tidy categories – sick or well; normal or abnormal – making those personally unaffected by the epidemic seem exempt from responsibility. We’ll find the misguided proteins or pathways correlated with aberrant behaviour, translate this knowledge into biomedical interventions and voila! Cured.
Aristotle thought the brain’s purpose was to cool the blood. Big leaps by Renaissance anatomists including Da Vinci and Vesalius and 19th century work by Broca and Ramón y Cajal helped map brain structures to functions, but progress has been slow due to the mind-boggling diversity among 100bn cells and their complex interactions. As a college student I learned about the brain as if it were like any other body organ and was taught that understanding the function of a few cells would suffice for explaining it in general. There is almost nothing in this simplistic view considered true today.
A clump of abnormal cells may cause breast or testicular cancer, but substance use disorders involve large swaths of neural real estate and processes such as motivation and learning. Excising brain cells or chemicals responsible for these sorts of global functions isn’t feasible, and the chance of finding a specific gene or chemical responsible for addictive behaviours is nil.
My own journey away from the destructive cycle of addiction started with factors outside my brain rather than direct biological intervention. When I began to see more clearly the terrible costs my drug use was exacting and decided to give sobriety a try, I availed myself of every tool. I benefited from clinical guidance, understanding employers, walks in the woods, shared coffee, tears and laughs with new friends in the same boat; I employed my obsessive-compulsive mind making flashcards for studying biopsychology, and relied on the healing powers of the passage of time. Each of these experiences affected my brain’s structure and function. This is my point. Would (yet) another pharmacological fix, electrical current targeting “addictive circuits”, or (coming soon, no doubt, to a clinic near you!) gene-editing strategy have been more efficient?
Biomedical research is more gung-ho than ever, but I’m not holding my breath. While my loss of naive idealism has been building for a while, my perspective, along with empirical evidence, has broadened quite a bit recently. It is clear that mental health is a function of critical wider connections as much as anything else; restoring or maintaining healthy brain function is a long-term, relational endeavour. Given the brain’s ceaseless and boundless dance with all that is, it’s a good bet that we will find more efficient and effective interventions for substance use disorders through its connections than in individually focused attempts to directly modify brain activity.
In more than 30 years as a neuroscientist, my most profound lesson has been that the brain and behaviour are products of multiple interacting influences, and the most powerful of these are located outside our heads, and therefore beyond the scope of any individual control. The brain acts as a conduit for such influences to shape who we are, but is not the source; therefore addiction is a symptom of dis-ease, rather than a cause.
• This article was amended on 3 January 2020 to distinguish Da Vinci and Vesalius as Renaissance anatomists and Broca and Ramón y Cajal as working in the 19th century and to give a more apt example of a consequence emanating from a cluster of abnormal cells.
• Judith Grisel is a behavioural neuroscientist at Bucknell University, Pennsylvania, and author of Never Enough: The Neuroscience and Experience of Addiction