Only in Old Mice, a Touch of Cannabinoid Helps Memory

Could a puff a day keep memory loss at bay? Perhaps, suggests new work from Andreas Zimmer and colleagues at Bonn University in Germany. The researchers treated old mice with a low dose of Δ9-tetrahydrocannabinal (THC), the main psychoactive component in cannabis, and found it improved the animals’ ability to learn and remember. The investigators went on to show that THC—at levels far below those needed to get high—appeared to rewire and rejuvenate aging brains. Treatment boosted the expression of genes related to synaptic function via epigenetic mechanisms and restored synapse number in the hippocampus to more at