How our understanding of addiction evolved from moral failing to chronic brain disease through neuroscience discoveries
Gollum's unhealthy obsession with the One Ring in The Lord of the Rings seems both strange and familiar: strange in its intensity, familiar in the mechanisms it reveals. Andy Serkis, the actor who portrayed him on screen, deliberately modeled this relationship on the concept of addiction 1 . Like Gollum, millions of people worldwide are trapped in destructive relationships with substances or behaviors, despite their full awareness of the negative consequences.
The path to understanding this apparent contradiction – the compulsive pursuit of what destroys us – has been long and winding. From prehistoric shamanic practices to high-tech brain scanners, our understanding of addiction has radically evolved, ultimately revealing that it is nothing less than a chronic brain disease 3 6 .
This article takes you on a journey through the centuries to discover how perspectives on addiction have moved from moral condemnation to biological understanding, and how this revolution has changed our therapeutic approach.
Before the term "addiction" existed, extreme dependency behaviors were often interpreted through religious or moral lenses. In antiquity, excessive substance consumption was sometimes associated with divine rituals, sometimes condemned as a personal vice. In the Middle Ages, demonic possession was more readily invoked to explain these uncontrollable behaviors.
Substance use viewed through religious rituals or personal vice frameworks
Addictive behaviors attributed to demonic possession or moral weakness
Swedish physician Magnus Huss describes "alcoholism" as a disease
The term "addiction" derives from the Latin addicere ("to dedicate to"), gradually taking its modern meaning in the 19th century: a compulsive dedication to a substance or behavior despite negative consequences 1 3 .
The decisive turning point in understanding addictions came in the second half of the 20th century with the development of neuroscience. Researchers discovered that all addictive substances, whether alcohol, nicotine, or illicit drugs, share a common property: they hijack the brain's reward system 3 6 .
This system, essential to our survival, relies on a key neurotransmitter: dopamine. Normally released in response to adaptive behaviors like eating or reproducing, it creates a sensation of pleasure that encourages us to repeat these indispensable actions.
With repeated consumption, the brain adapts: dopamine receptors become less sensitive, natural dopamine levels decrease, and the person no longer consumes to seek pleasure, but to escape discomfort 6 8 . Dr. George F. Koob masterfully demonstrated how the stress system (norepinephrine, dynorphin) becomes overactivated in response to this artificial stimulation, creating anxiety and distress when consumption stops 8 .
Contemporary research has identified three successive stages in the establishment of addictive disease 6 :
Intense activation of the reward circuit and conditioning that associates environmental cues with consumption.
Appearance of dysphoria and anxiety between consumptions, with consumption mainly aimed at relieving this discomfort.
Impairment of executive functions (prefrontal cortex) responsible for impulse control and decision-making.
| Brain System | Main Role | Alteration in Addiction |
|---|---|---|
| Reward System (Nucleus accumbens, extended amygdala) |
Motivation, pleasure, learning | Desensitization, need for increasingly more substance to achieve effect |
| Executive System (Prefrontal cortex) |
Impulse control, decision-making | Loss of control, compulsive behaviors |
| Stress System (Hypothalamic-pituitary-adrenal axis) |
Stress and emotion management | Overactivation, anxiety, negative state during withdrawal |
In the 1950s, psychologists James Olds and Peter Milner conducted a series of experiments that would revolutionize our understanding of the mechanisms of pleasure and motivation 3 .
Researchers implanted electrodes into specific regions of rats' brains, particularly in the septal area and hypothalamus. The animals were placed in a cage equipped with a small lever. By chance, they discovered that when the rat pressed this lever, it triggered a weak electrical stimulation in its own brain via the electrodes.
Progression of rat behavior in self-stimulation experiments
The results were spectacular: rats self-stimulated frantically, up to several thousand times per hour, neglecting food, water, and sleep. They preferred this stimulation to any other activity, even crossing electrified grids to access the lever. Olds and Milner had discovered what they called the brain's "pleasure centers."
The importance of this discovery was considerable: it revealed the existence of a brain circuit dedicated to reinforcing behaviors essential to survival. This circuit, which we now know as the mesolimbic reward system, with dopamine as the key neurotransmitter, is precisely the one that all addictive drugs hijack 3 6 . This foundational experiment provided the first robust animal model for studying the neurobiological mechanisms of reward and addiction.
| Substance Type | Examples | Main Mechanism of Action on Dopamine |
|---|---|---|
| Psychostimulants | Cocaine, Amphetamines | Blocking reuptake or increasing dopamine release |
| Opioids | Heroin, Morphine | Activation of opioid receptors, inhibition of GABA neurons that normally inhibit dopamine release |
| Nicotine | Tobacco | Stimulation of nicotinic receptors on dopaminergic neurons |
| Alcohol | Alcoholic beverages | Complex actions: increased dopamine release, modulation of GABA and glutamate receptors |
Progress in understanding addictions would not have been possible without the development of sophisticated research tools. Today, scientists have a veritable arsenal to explore the mechanisms of dependence.
Rodents are used to reproduce certain aspects of addiction in a controlled system 2 , allowing study of neurobiological mechanisms and testing of potential treatments.
fMRI and PET scans visualize brain activity and structure in living humans, observing brain areas activated by anticipation or consumption of a drug.
Knockout mice help identify the role of specific genes, such as mice modified not to express a certain receptor (e.g., dopamine D2 receptor).
Animal model where the subject self-administers a substance, allowing evaluation of addictive potential and study of seeking behaviors.
Animal Models
Self-Administration
Brain Imaging
Genetic Studies
The journey of understanding addiction is one of progressive humanization. We have moved from a moralistic model, where dependence was considered a character weakness or vice, to a medical model that recognizes addiction as a chronic brain disease 6 8 .
In France, tobacco and alcohol, legal substances, remain the deadliest, responsible for more than 115,000 deaths per year and costing society 156 and 102 billion euros respectively 4 .
"It is not, as some continue to repeat, a moral failure" 8 . Understanding that dependence durably alters the brain circuits of decision-making and self-control means accepting that recovery is a long process, fraught with obstacles, but possible, especially when science and humanity walk hand in hand.