But among experts, the appraisal of addiction was shifting. Medical, health, and research groups were all moving toward a much more inclusive characterization. It de-emphasized the chemicals themselves, so that the relative greater strength of, say, heroin to nicotine was less of an issue. The new definition focused instead on the wide variation in how people respond to drugs. For a substance to be considered addictive, it no longer had to wreck the lives of every user. It was enough that only some people got badly hooked. In
