Well, it's vastly more sophisticated than the strapping-masks-on-monkeys studies that the War on Drugs was using for cover in the 70s and 80s. Looks like there are even some findings of scientific value. My main problem with this is that when it comes to starting (as opposed to continuing) use of hard drugs, rat studies don't seem likely to tell us much about human behavior. To the extent that adolescents are going to listen to adults at all, it makes sense to preserve credibility by not needlessly exaggerating the dangers of something like marijuana.

The study is interesting in its own right, even though the interpretation is, at best, questionable. The authors state the "gateway hypothesis" as the hypothesis that "cannabis exposure has an enduring impact on hedonic processing," but that is inaccurate. At least, that's not how most of us understand the gateway hypothesis. The gateay hypothesis is not the hypothesis that exposure to a drug affects hedonic processing, but rather, as I understand it, the hypothesis that administering one drug will increase the likelihood that a second-drug will be repeatedly self-administered. If the researchers had shown that the THC-exposed rats were more likely to begin and maintain self-administration of heroin, it would be much more convincing evidence for some kind of a gateway effect,

You could post in comments over at Randal Parker's "futurepundit", where this was already discussed credulously.

The current issue of Behavior Genetics (Jul 2006) is all about substance abuse, gateway theory, etc. Looks like it's mostly due to common underlying heritable factors (pretty much across the board) and shared environment (for drug of choice, though not necessarily for frequency of use). Didn't see anything arguing for the interesting version of the gateway theory, but then this library server is being retarded and not letting me read the damned articles.

Aside from any other considerations (such as the rather low population samples), the really diabolical thing about this report is that it presented supposed "findings" in direct opposition to its own conclusions.

Those that have read the report will have seen on p.7 clear as day:
"The periodic exposure to low-dose THC during adolescence did not appear to predispose animals to an increased sensitivity to initiate heroin self-administration."

In other words all the rats responded in exactly the same way to getting addicted, and there was NO DIFFERENCE in the ones that had been exposed to THC, and the THC did not act as a gateway drug.

So, what kind of hidden agenda is there, when this fact is trumpetted as "Cannabis IS gateway to heroin". Seems to me that these people are very dishonest, and are operating to an undisclosed agenda.

If anyone has another explanation fro this debacle, I'd love to hear it.