© Rafael Marchante / Reuters
Tests with low doses of cannabis on mice led to some surprising results, with stoned elderly mice matching their sober teenage counterparts in a series of cognitive tests
It's a simple fact of life, with old age comes cognitive decline.

However, a group of German researchers believes a daily dose of cannabis extract could help boost memory and learning potential in elderly people.

In a study published Tuesday in the journal Nature Medicine, researchers from the University of Bonn, Germany, found that regular doses of tetrahydrocannabinol (THC), the main psychoactive constituent of cannabis, boosted memory and learning in elderly mice.

The findings are counter intuitive, given that heavy cannabis use is known to impair both memory and learning ability in adolescent humans.

Scientists are now planning human trials later this year.

Researchers conducted experiments on mice of various ages, dosing them daily with a low amount of THC. The mice were then subjected to a number of cognitive tests, including measuring how quickly they solved a water maze and how quickly they recognized familiar mice.

Without THC, the younger mice passed the tests with flying colors, but once dosed, they struggled much like the older ones struggled without the cannabis constituent.

However, once given the drug, the older mice thrived and their test scores were on a par with their younger, sober counterparts.

Furthermore, the THC benefits lasted for weeks after the older mice were initially dosed.

"These results reveal a profound, long-lasting improvement of cognitive performance resulting from a low dose of THC treatment in mature and old animals," the scientists said.

The team believe that THC stimulates the body's endocannabinoid system, a group of endogenous (internal) cannabinoid receptors located in the brain and throughout the central and peripheral nervous system in mammals, that become less active with age.