Old mice given THC, the active ingredient in marijuana, did better on learning and memory tests — though young mice did worse. It’s too early to say if this applies to humans, but the findings do shed some light into the possible effects of the drug.

Marijuana is known to have pain-relieving effects. People also think it might be bad for cognitive function, but there hasn’t been a lot of reliable research in this area. In an study published today in Nature Medicine, researchers implanted young, full-grown, and old mice with little pumps that released tetrahydrocannabinol (THC) into them every day. The scientists then gave the mice various learning and memory tests. Young mice given the THC did worse, but the old ones did better.

THC is one of the key components of cannabis; the chemical interacts with the numerous cannabinoid receptors in the central nervous system. In today’s study, all the mice (young, full-grown, and old) received low doses of THC via the pump for 28 days. After 33 days — so, after the mice were no longer getting the THC — scientists gave the mice the Morris water maze test, where mice have to escape a round pool by finding a platform that helps it escape.

In the control group, the older mice did worse than the young mice, which makes sense. The interesting part is that young mice given THC did worse than the control group. And older mice given THC did better than the control group. In fact, they did as well as the young mice in the control group.

These are very early results which should be taken with a grain of salt. Next, the team will do more investigations to learn more about the cause of these results, and try these experiments in other animals to see if the findings hold up.