Addiction is not weak will: what happens to the reward system

“I decided to stop. I have decided a thousand times.” That is what a man told me who was meticulous at work, dependable at home and merciless towards himself. He could not understand how someone who runs projects and raises children can lose an evening battle with a bottle standing on a shelf. His explanation was short and cruel: “I’m just weak.”

That explanation is the most common one and the least useful of them all. Addiction is not a lack of willpower. The people I meet often have more willpower than average — that is how they managed years of a double life, going to work with a hangover and telling no one. The problem is not the will. The problem is that the system driving the will has been rebuilt along the way.

One more warning before I go on, because it matters more than anything else here. Stopping alcohol or tranquillisers (benzodiazepines) abruptly can be life-threatening. Withdrawal from these two groups can cause seizures and delirium and belongs under medical supervision. If you are thinking of stopping, talk to a doctor first — not on your own, not overnight, and not because you read an article online.

The reward system is not a pleasure system

The most common misunderstanding is that dopamine is the “happiness chemical”. It is not. Dopamine in the midbrain pathways — above all from the ventral tegmental area to the nucleus accumbens — does not fire when things are good. It fires when things are about to be good, and especially when the promise is bigger than expected.

Wolfram Schultz showed this in monkeys back in the nineties. If an animal receives juice with no warning, dopamine neurons spike at the juice. If a tone always sounds before the juice, the spike gradually migrates from the juice to the tone. The juice itself then does almost nothing. The signal is not “pleasure”, the signal is “prediction error” — the gap between what you expected and what you got. It is a learning signal.

That is why it matters what happens, in this logic, with substances and behaviours that hit the reward system directly and harder than anything we met in evolution. The learning signal does not fade the way it should. The brain keeps learning — concluding each time that this mattered more than it had predicted.

“Wanting” and “liking” are not the same thing

In the nineties Terry Robinson and Kent Berridge proposed the explanation I find most useful when I describe to someone what is happening to them. They separated two processes that everyday language fuses into one: wanting (craving, being pulled) and liking (enjoying). Different neurochemistry drives each. Wanting is dopaminergic. Pleasure has more to do with opioid and cannabinoid systems in small hotspots.

With repeated use the dopamine system becomes sensitised — more responsive, not less. At the same time the enjoyment melts away. The result is a state people describe with the same confusion: “I don’t even like it any more. And I still have to.” That is not a contradiction and not an excuse. It is a description of what happened — two levers that went in opposite directions.

The same theory explains why cues are so powerful. Not the glass, but Friday. Not the cigarette, but the coffee after lunch. Not the slot machine, but the notification sound. Stimuli that were present alongside the reward take on incentive salience: they start pulling attention and triggering desire on their own, even when the person has consciously decided nothing. People often find this a relief — craving is not proof that you “really wanted to”. It is a learnt response to a cue.

The prefrontal brake works worse exactly when you need it

The other half of the story sits at the front. The prefrontal cortex handles what we call executive functions: holding back an impulse, weighing consequences, giving a distant goal priority over a near one. Imaging studies in people with addiction consistently show reduced activity and altered connectivity in these regions, particularly the orbitofrontal and anterior cingulate cortex.

So it makes no sense to test your resolve at the moment craving peaks. That is like testing the brakes halfway down the hill. Everything that works — a plan for what you do on Fridays; an agreement about who calls you; moving the bottle out of the flat; a different route home — works because it happens earlier, while the brake is still functioning.

Why things get worse even when the pleasure is gone

George Koob proposed the idea of allostasis for this. The body works towards balance, but after repeated upheavals it does not restore that balance at the old point — it sets it lower. Baseline mood drops. The opposing processes that at first only softened the effect become a permanent background: restlessness, irritability, empty tension, poor sleep.

Once that happens, the motive flips. At the start a person seeks a pleasant state; later they are fleeing an unpleasant one. Koob calls this the shift from positive to negative reinforcement. Stress systems come online — corticotropin-releasing factor and dynorphin in the extended amygdala — and this is the part that explains why withdrawal is so unbearable and why people return to something they stopped enjoying long ago.

If you are interested in what arousal and sleep do in the body, I have written about it in the piece on hyperarousal and insomnia — the mechanisms are related and often intertwine with addiction.

What this means for guilt

When someone grasps that this is a rebuilt system and not a character flaw, two things usually follow. The first is relief. The second, mentioned less often, is unease: “If it’s my brain, then there’s nothing I can do.” That is not true, and the distinction matters. An explanation is not an excuse. Responsibility stays — but it moves. You are no longer answerable for having a craving. You are answerable for what you do with it and what environment you build.

This shift is therapeutically crucial, because shame and addiction work in a loop. Shame increases distress, distress increases desire, use increases shame. I have written about how shame differs from guilt and why it is a far worse motivator in the piece on healthy and toxic guilt.

Why it does not happen to everyone

The large majority of people who ever drink do not develop an addiction. That matters, because it shows the substance alone is not a sufficient reason. Twin and family studies put the heritable share of addictions at roughly half — which means half sits elsewhere. Heritability here does not deliver a “gene for drinking”; it delivers small differences in how strong the response is, how quickly tolerance builds and how unpleasant waiting feels.

The other half is history and setting. Early exposure, chronic pain, untreated anxiety or depression, loneliness, hopelessness and childhood abuse markedly raise the risk. For many people the substance first worked as a solution — it settled something that would not settle otherwise. I have written about how a symptom often does a job in the piece on the symptom as a message. Overlook that job, and stopping brings back precisely what the substance was shielding you from.

Why the brain does not bounce back at once — and why it does

Imaging studies in people who have stopped show that part of the change repairs itself, but slowly. Metabolic activity in prefrontal regions after long abstinence from methamphetamine recovers partially only after months, not weeks. That is important for expectations: the first months are not the measure. The feeling that “nothing is getting better” is often just a description of the lag.

It is also a good reason for hope. The same mechanisms that built the pattern — repetition, context, learning — also dismantle it. I have written about what neuroscience tells us about change in the piece on neuroplasticity and therapy.

Where this explanation fails and what it cannot do

Now the part usually left out. The model that explains addiction as a brain disease faces serious objections and is not the complete picture.

First, most people who develop an addiction come out of it — often without treatment, in their thirties or forties, as circumstances change. Gene Heyman and Wayne Hall have pointed out that such high rates of spontaneous recovery sit awkwardly with a chronic, progressive brain disease. If it were purely about rebuilt circuitry, we would not expect so many people to get out once they find a job, a partner or a child.

Second, circumstances count for more than the model admits. Vietnam veterans who were addicted to heroin during the war overwhelmingly stopped after coming home, without treatment — not because they were stronger, but because everything around them changed. Similarly, studies rewarding abstinence have shown that use falls for a proportion of people when a concrete, reachable alternative reward exists. Choice has not vanished; it is simply heavily weighted.

Third, poverty, isolation, chronic pain, untreated trauma and inaccessible care are not the background of addiction but often its engine. Without those facts, a neurobiological account can become a convenient way of relocating the whole problem inside one person’s head and letting the surroundings off.

And fourth, practically: understanding a mechanism is not the same as changing behaviour. I have sat with people who knew more about dopamine than I do, and it did not help by itself. What helped was a change in where they were, who they were with and what they did at seven in the evening.

What to do with this

Because the cue outruns the decision, everything that happens in advance is worth the most. Change the setting before the setting turns into a trigger. Decide about the route home, not about how much you will drink. Make an arrangement with one person who knows, rather than ten who guess.

For substances there is medication with solid evidence behind it — for alcohol, for opioids, for nicotine — and using it is not a sign that you failed to manage alone. I have written about when a doctor is the sensible first step in a separate piece. Therapy alongside does the other work: what the substance or behaviour is actually doing for you, what happens when it is gone, and what goes in its place.

I should also mention harm reduction. Full abstinence is not immediately possible for everyone, and intermediate steps — safer use, less frequent use, regular medical monitoring — are not a betrayal of the goal. They are a legitimate, evidence-supported route that keeps people alive long enough for something to change.

What to remember

Addiction is not weak will. It is a rebuilt learning system in which wanting grows, liking fades, and the brake works worst exactly when you need it most. Cues trigger desire before you decide, so the plan is made ahead of time.

Stopping alcohol or tranquillisers abruptly can be dangerous — that belongs under medical supervision. An explanation is not an excuse and responsibility does not disappear, but it shifts from the feeling to the action. And circumstances — where you are, who you are with, what you have — are not the backdrop of this story. They are half of it.