There's Hope for Old Stoners

If you're old enough, you may come to like your prime minister a lot more on October 17. That's when the recreational use of marihuana will become legal in Canada.

If you're old enough as in "old" enough.

Researchers in Germany have found that an active ingredient unique to cannabis produces some remarkable effects on the minds of really old mice.  After a few weeks of low dose THC, Methuselah mice, 16 to 18 months old, were mentally rejuvenated.

We implanted so-called osmotic mini-pumps—tiny pumps that we put under the skin of these mice—and they constantly released the drug that we wanted to administer. And then, after four weeks, we stopped the delivery, waited for a week, and then afterwards, there were several tests on learning and memory.

A very simple test, for example, is that mouse needs to learn how to find a hidden platform. And mice learn this typically within a few days—actually, they're quite good. 

And what we observed was quite staggering. They remembered where the platform was just as well as a young animal—and also, their working memory was absolutely indistinguishable. Then we tested the animals in many different paradigms that also test memory function, and we basically couldn't distinguish [between] the old mice and young mice. These [old mice] were between 12 and 18 months, which is very old for a mouse.

But there's a hitch. There's always a hitch. The mental improvement was only found in old mice.

Cannabis is a drug that has opposite effect on young animals as opposed to old animals. It worsens memory in young mice. It also worsens memory in young humans.

So, how does it work on geezers? It reverses your endocannabinoid decline, whatever that is.

We had previously observed that the endocannabinoid tone declines as we age, so the levels of endogenous substances decrease in older individuals. And this means they're present inside our bodies to begin with. So what the plant compound does is just mimic our endogenous compounds. What we were attempting to do is to normalize the level, or bring it back to the level of young individuals.