THE MOLECULE OF MORETHE REASON ADDICTS THINK SMOKING CRACK
IS BETTER THAN SNORTING COCAINEThe ability to trigger dopamine in the desire circuit is what makes a
drug addictive. Alcohol does it, heroin does it, cocaine does it, even
marijuana does it. Not all drugs trigger dopamine to the same degree,
though. The ones that hit dopamine the hardest are more addictive
than ones that are more restrained. By triggering the release of more
dopamine, the “hard hitters” also make the user feel more euphoric,
and stimulate the most intense craving when the drug is gone. Intensity
varies by drug. Pot smokers are generally less desperate to get more of
the drug than cocaine addicts. But beneath all the differences is the
commonality of the dopaminergic rush and subsequent craving.
Many factors account for the differences. The chemical structure of
the molecules that make up each drug plays a large role; some chem-
icals are better than others at pushing dopamine along its path. But
there are other considerations as well. For example, the crack cocaine
that users smoke is essentially the same molecule as powder cocaine
that users snort, but crack is far more addictive—so much so that when
crack became widely available in the 1980s, it took the world of recre-
ational drug use by storm.
What’s so “great” about crack that allowed it to take over the
cocaine market, and chemically enslave thousands of people? From a
scientific perspective, the answer is simple: the rate of onset of action.
Consider a drug such as alcohol that triggers the release of dopa-
mine. The faster it gets into the brain, the higher it will make its user.
In Figure 2 the horizontal axis shows how much time has gone by and
the vertical axis shows how much drug has gotten into a user’s brain. If
someone is sipping a glass of Chardonnay, the graph will gently rise to
the right. On the other hand, if that same person were to start taking
shots of vodka, the graph would show a steep slope that quickly shoots
upward.