Is addiction just a habit that got too strong?

Partly, perhaps, but scientists disagree. One influential account says addiction is the endpoint of a series of transitions: a drug is first taken voluntarily because it has reinforcing, often hedonic, effects; control is gradually lost; and the behavior becomes habitual and ultimately compulsive. In that view, it really is a habit that has grown too strong.

A rival account says the key change is not in habit but in wanting. Reward has separable parts, wanting and liking, and the brain circuitry for wanting is dissociable from the circuitry for liking. The incentive-sensitization theory says addiction is excessive amplification of wanting, especially when triggered by cues, without necessarily an amplification of liking. In the extreme, a user may want a drug more and more while liking it less.

The evidence is not settled. In rats, overtraining can induce habits. But a 2018 paper reported five failed attempts to show that overtraining makes humans inflexible, and it suggested that compulsive people may have weak goal-directed control rather than overactive habits. A 2025 review by the incentive-sensitization theory's own originators lists habit theories as one of several competing accounts. The honest answer is that habit is one serious candidate among several, and the evidence does not yet pick a winner.