“Ohhh, so now pot’s a ‘medicine,’ right? Now they’re handing out prescriptions? You gotta be kidding me!”

I’m in a taxi driven by an irascible guy who looks like he’s about fifty and has been driving a cab for pretty much that whole time. I’m guessing he’s constructed his moral world view by watching Archie Bunker on All in the Family reruns. He’s wrestling the cab through New York traffic with the finesse of a matador and the impassivity of the dictator of a small Latin American country.
When I climbed in at Penn Station, I made the mistake of telling Archie that I was going to meet a researcher who studies medical marijuana. The result has been a twenty-minute tirade that has been by turns vituperative, dismissive, and caustic. Also wildly entertaining.

But it’s been difficult to figure out what his stance on marijuana is. He’s not against it per se. Certainly he’s not morally opposed. It’s more that he thinks the whole idea is a grand joke.

“Sick people getting stoned? Hey, why not? And why stop with marijuana? Why not try LSD?” If your reality really sucks, he says several times, why not get as far away from it as you can?

As I’m listening to this free-association rant, keeping an eye out for the bumpers of other cars, I’m having two reactions more or less simultaneously.

First, what I’m hearing sounds eerily familiar. The opinions that Archie is spouting are pretty much what I was saying a year ago when I first started writing Stoned:  A Doctor’s Case for Medical Marijuana. In fact, I’m pretty sure that if Archie and I had met a year ago, we would have shared a good laugh about the grand joke of “medical” marijuana.

But it’s my second reaction that surprises me: I find myself disagreeing. With a New York City cab driver. I should state for the record that this is not something that I have ever been inspired to do before.

Marijuana does offer benefits, I tell him during one of his brief pauses for breath. I was surprised, too, I say mildly. It’s useful in treating certain types of pain, like—

But Archie isn’t listening. He’s off and running again, talking about how people these days are coddled, about how they want everything handed to them. How getting high is just getting high, it’s not treating anything.

We slice across three lanes of traffic, cutting off a bicycle messenger, a bus, and a delivery van, and screech to a halt in the general vicinity of the curb. I pay him, backing out of earshot as fast as I can. As I turn to make my escape, Archie is still ranting about Obamacare and the DEA and—for reasons that are best left to the imagination—Girl Scouts.

I’m pretty certain marijuana really does offer some medical benefits.  In the past year, I’ve talked with dozens of experts, patients, and activists. I’ve slogged through hundreds of studies of marijuana. I can even say that I’ve had some limited experience with its effects on me.  Along the way, I’ve graduated from a hard-nosed skepticism to an open-mindedness that I never would have believed possible a year ago.

So: Does marijuana work?

Well, one thing I’ve learned is that this isn’t the right question to ask.

Does a hammer work? Sure, if you want to pound a nail. But if you want to fix a frozen iPhone, not so much. So whether marijuana “works” depends on what you want it to do.

Take one example:  Pain.  Marijuana seems to be quite effective in treating neuropathic pain (that’s pain caused by nerve damage).  In researching Stoned, I spoke with Barth Wilsey, an anesthesiologist at the University of California, Davis, who has done several clinical trials of marijuana for management of neuropathic pain.  These are studies that used smoked marijuana (e.g. in a joint), with a placebo control.  (Yes, there is ‘placebo’ marijuana, from which the active ingredients—cannabinoids—have been extracted using much the same process that is used to remove the caffeine from coffee beans).  Those studies have found that marijuana can be very effective in reducing neuropathic pain, and probably also in increasing ability to function.

For instance, one study(1) of 39 patients tested high-dose marijuana at 7% tetrahydrocannabinol (THC), low dose marijuana (3.5%) and placebo.  Patients were randomized and blinded to which version they were getting.  That study found significant decreases in pain for both the high- and low-dose marijuana, compared to the placebo.

That’s neuropathic pain, but what about regular ‘nociceptive’ pain?  That’s more run-of-the-mill pain that’s caused by injury to bone or tissue.  This is the kind of pain that you’d have after a hard workout, for instance, or pain due to arthritis or a broken bone. Could marijuana be effective for nociceptive pain, too?

Maybe, but the evidence is not nearly as strong, even in highly-controlled laboratory studies.  In these sorts of studies, you expose volunteers’ skin to piece of metal that’s been heated to a temperature that most of us would agree is uncomfortable (about 45 degrees Celsius, or about 113 degrees Fahrenheit). That’s their “pain threshold.” Then you see whether a drug lets people tolerate a higher temperature without squirming. In one such study, marijuana doesn’t seem to increase pain thresholds as much as some other drugs, such as morphine.(2)

Also, there just haven’t been many good studies, mostly because there are lots of other treatments for nociceptive pain that we know are effective, like acetaminophen, nonsteroidals, and opioids (for severe pain).  So there hasn’t been a lot of incentive to study marijuana, when there are many other effective drugs already available.

So does marijuana ‘work’?  If you have neuropathic pain, maybe it does.  At least, it may be worth a try.  But if you have regular, nociceptive pain, the jury is still out.

Where does that leave us? Is marijuana a medicine? A year ago, I found that idea as laughable as Archie does. Pot? A medicine? That proposal seemed as wishful and deluded as declaring single malt Scotch a medicine.

And I have to say I am still skeptical. Marijuana’s ingredients aren’t as refined and defined as the ingredients in a pill are. A joint is hardly a medicine.

So I think of marijuana as more or less equivalent to an herbal remedy. It’s essentially plant-based stuff with numerous active and inactive ingredients, only some of which we understand. And those ingredients make an appearance in varying doses and ratios among plants and between crops.

That’s not a fatal flaw. In fact, there are plenty of herbal remedies that are widely used, and even recommended by doctors. So as long as we think of marijuana as an herbal remedy, I’ve become a pretty strong believer.

Sure, we need more research.  We need to do much more to understand its benefits, and also its risks.  But I think we know enough now to be able to conclude that for some people—though certainly not everyone—it might be a reasonable treatment.

(1) Science Direct abstract: ‘A Randomized, Placebo-Controlled, Crossover Trial of Cannabis Cigarettes in Neuropathic Pain’, The Journal of Pain, Vol. 9, No. 6 (June 2006)

(2) Anesthesiology abstract: ‘Lack of Analgesia by Oral Standardized Cannabis Extract on Acute Inflammatory Pain and Hyperalgesia in Volunteers’, Pain Medicine (July 2008)

Want to comment or contribute?

Join the debate on twitter @VolteFaceHub