A recent study shows that using marijuana as an adolescent could increase one's chances of ending up in drug rehab for heroin addiction. There has long been disagreement over whether marijuana can be called a "gateway" drug: some feel that young people using marijuana will get into heavier drugs because the drug use environment offers the opportunity to get them, and others say there is no such connection. A new study out of Karolinska Institute in Sweden may settle the argument: According to the study, marijuana might well be a gateway drug, but it's not because of the environment. The study indicated that marijuana alters brain chemistry. Yet another good reason to get into drug rehab.

The Swedish study was done on twelve rats: six were exposed to THC (the active chemical in marijuana) and six were not. When the rats were 28 – 49 days old (equivalent to 12 – 18 years in humans), researchers simulated the six rats having one joint every three days. After this, all twelve rats were given self-administering catheters that allowed them to "inject heroin." The rats' heroin use "leveled out" at the same time, but the rats that had been given the THC stabilized their intake at a higher level than the others. This suggests that those rats were less sensitive to the effects of heroin and, consequently, needed higher doses.

This is the exact sequence that occurs with the use of heroin and other opiates, and is a major contributing factor to addiction and the need for drug rehab.

The researchers concluded that the larger doses for the "THC" rats indicate an increased risk of heroin addiction. Translate this into marijuana abuse in teens and we have a potential problem. Even if the drug environment doesn't lead then down the path toward heavier drug use, this study does suggest that the alterations in his brain chemistry may be setting him up for addiction if they even try it out.

In fact, it wouldn’t have to be heroin: It could be an opiate prescription painkiller like OxyContin, taken for legitimate reasons. If the teen had previously used marijuana, his tolerance for the painkillers could be increased and he would therefore have to take more of them, which would increase the risk of addiction, and, even if the drug was gotten by prescription, he could still need drug rehab to get off them.

Regardless of the reason behind it – environment, brain chemistry, or simply the fact that marijuana causes impaired judgment and a disassociation from reality – enough people have gone from marijuana to harder drugs for it to be a concern. And, even without that gateway ever being walked through, marijuana is a dangerous drug that, in itself, is enough reason to find a successful drug rehab program. But the risk of going from marijuana to heroin or other opiates makes stopping marijuana use all the more vital.