When the researchers examined the brains of the elderly mice, they discovered that the ones who'd been regularly dosed with THC had sprouted neural connections in the hippocampus, the part of the brain that deals with memory, among many other important cognitive functions. In fact, they actually began to resemble the brains of the young mice who never received any THC.
Considering the dramatic shift in public perception of marijuana that's occurred over the last few years, this revelation may help it ditch the stigma even further. Obviously, there will need to be extensive testing done on humans to determine what sort of cognitive impact THC actually has on our brains (and what an appropriate dosage is), and whether it has any long-term negative consequences. The good news, though, is this latest batch of research has enabled the team to secure funding from the German government to begin testing on older adults soon.