Addiction isn't just chemical. Decades of research show that's the half most products ignore.

The half of the habit no patch can reach.

In the early 1990s, two researchers at Duke University — Jed Rose and Frederique Behm — ran a series of experiments that quietly upended the chemical-only model. They gave smokers denicotinized cigarettes containing virtually no nicotine. The cigarettes still suppressed craving. In follow-up work, they showed that the inhalation ritual itself — the act, the airway sensation, the hand-to-mouth motion — was doing measurable work that nicotine alone could not.

A subsequent review by researchers at Queen Mary University of London (Przulj, McRobbie & Hajek, 2012) named this second half of the addiction directly: sensorimotor replacement. Their conclusion: the smell, taste, inhaling and exhaling, airway sensations, and the act of holding something to the mouth function as secondary reinforcers that contribute independently to the reward of smoking — and addressing them alongside nicotine support enhances cessation outcomes.

Sayette and Parrott at the University of Pittsburgh (1999) added a third piece: a controlled study showing that exposure to a pleasant scent during a craving moment measurably reduced the urge to smoke — independent of any nicotine intake. Subsequent work in 2019 replicated and extended the finding.

A 2025 study in Frontiers in Psychiatry on the gestural component of smoking went further: the hand-to-mouth motion and ritualized motor routine were found to persist independently of nicotine dependence severity. In plain English, the ritual is a separate dependency that pharmacotherapy alone doesn't touch.

This is the half of the habit Lio is built for.