One of the charges leveled at cannabis is that it acts as a “gateway drug” to bigger and badder substances, or to a life of crime itself. It makes otherwise liberal, critical-minded people support its illegality, despite acknowledging its lack of harmful effects. While we’ve touched upon this issue in past articles, it’s time we really dug into the matter and led it to rest.

Hard science

Chemically speaking, evidence that cannabis use leads to substance abuse is shaky and tenuous. The most convincing study I could find described that when juvenile rats are given cannabis, their dopamine receptors are blunted – basically meaning their tolerance to dopamine-inducing events and substances (i.e. other drugs) is heightened. The same effect was not observed in fully matured, adult rats. However, just because an individual – be they rodent or human – has a higher pleasure threshold with “dopamine inducing substances” doesn’t mean they’re any more likely to seek those substances out.

Another study – deviously referenced by this anti-drugs website as “proof” that THC enhances the effects of other drugs – found that administering THC to rats had no effect on their appetites for harder substances, but did seem to make them more interested in nicotine, implying cannabis, if anything, is actually a “reverse-gateway” drug.

Most damningly, one paper suggests that the gateway hypothesis may just be an artifact of faulty logic: just because the majority of cocaine and heroin users (in the West) have previously used cannabis, does not logically imply that cannabis was the cause of their subsequent hard drug use. After all, the majority of such users have also previously used alcohol and tobacco too (in fact, some studies have implied that alcohol and tobacco users are overwhelmingly more likely to use harder drugs than teetotal people and non-smokers – but once again, association does not imply causation!). The paper also emphasizes that proponents of the gateway hypothesis have yet to pinpoint any chemical cause that might lend it hard credibility.

Social science

In the West at least, it’s been suggested that the “gateway” illusion arises from simple social dynamics: cannabis is far more readily available than other nastier substances, and for most people is accessible at a far younger age. In other societies, this illusion doesn’t exist in the first place: in Japan for example, roughly 83% of hard drug users did not use cannabis first.

Also, many Western studies bear out a different narrative altogether. Using states that recently legalized medical marijuana as a lens, one study found that increased cannabis use in a society can actually decrease instances of heroin use. So much for one leading to the other.

But even if cannabis use doesn’t lead to hard drugs, some commentators still emphasize the fact that it can lead to involvement with crime. However this has nothing to do with the drug itself, rather everything to do with the way our society structures itself: if weed were legal, this wouldn’t be a problem. Why weed is illegal in the first place is story that will make you fume with a sense of injustice: here is a very good overview that pulls no punches. Add to this the inhuman practice of mandatory prison sentences for cannabis possession, and parts of our society have found themselves in a position where, yes, weed use invariably leads to criminality – because the system itself actively promotes it. Legalizing weed would do away with this whole “gateway to crime” dynamic practically overnight.

So to summarize, scientific evidence for the “gateway hypothesis” is unconvincing, aspects of it often selectively cherry-picked and twisted to fit existing narratives. And when weed does cause issues, it is because they are socially created.

In the end, cannabis itself isn’t harmful – our society’s attitude towards it is.

More interesting stuff related to this topic:

This paper on the gateway hypothesis, for those who don’t mind a bit of science.

This TED talk on addiction: underlining the real reasons why people take hard drugs (hint: it’s all to do with a person’s social existence – or lack of).