We all forget things sometimes, whether it's our car keys or the words to a song. As we age, changes in memory are normal, but we also become more susceptible to memory loss linked to dementia. Now, researchers at the University of Bonn in Germany, suggest a daily dose of THC in marijuana can strengthen brain connections to reverse the effects of aging in the elderly.

In the study, published in Nature Medicine, German researchers found THC to have a "very robust and profound effect" in reversing brain aging and restoring learning and memory in mice in four weeks. The research team simulated the endocannabinoid system with THC — involved in balancing bodies' response to stress — in older mice as a potential way to improve brain function. THC affects us by imitating similar molecules in this system, which fulfill important functions in the brain.

“With increasing age, the quantity of the cannabinoids naturally formed in the brain reduces,” said Professor Andreas Zimmer, from the Institute of Molecular Psychiatry at the University of Bonn and member of the Cluster of Excellence ImmunoSensation, in a statement. “When the activity of the cannabinoid system declines, we find rapid ageing in the brain.”

Previous research on young adults and frequent marijuana use has found THC leads to a decline in cognitive function, but little is known about its effect on the older population. For example, teens who smoked pot every day for about three years performed worse on long-term memory assessments. Moreover, the hippocampus — the brain region associated with long-term memory — looked abnormal in an MRI.

This prompted Zimmer and his colleagues to test the effects of THC on the aging brain of mice. The team gave the mice a small dose of THC at age two, 12, and 18 months over a period of four weeks. The amount administered was too small to give them psychoactive effects. After four weeks, the researchers tested the mice's ability to perform cognitive tasks, such as finding their way through mazes and the recognition of other mice.

The findings revealed older mice given THC performed as well as the young mice in the control group. However, aging mice given the placebo showed learning and memory loss, which is commonly associated with aging. In other words, the brain aged much faster when mice did not possess any functional receptors for THC.

Meanwhile, further studies showed THC increased the number of connections between brain cells in the hippocampus. This means memory is strengthened in older mice, which could potentially open up new options when it comes to treating dementia.

"Although there is a long path from mice to humans, I feel extremely positive about the prospect that THC could be used to treat dementia, for instance," said Svenja Schulze, the North Rhine-Westphalia science minister, in a statement.

Previous research has shown THC appears to remove the amyloid clumps — the Alzheimer's hallmark — from nerve cells grown in the lab. However, no studies or trials have looked into the effects of marijuana or its components on the causes of Alzheimer's diseases in people. Studies like Zimmer's do show some promise, but more research is needed to understand the wider effects of these components before coming to any conclusions.

Zimmer and his colleagues are now planning human trials to see whether older people can benefit from low doses of THC, and if so, from what age can they see benefits. There is no formula that can equate mouse months into human years. The trial will use purified THC rather than weed so the dosage can be controlled, possibly cia mouth spray.

In a climate where only only 29 states and Washington, D.C. have laws in place medical marijuana, it's unlikely doctors will prescribe THC as a means to prevent cognitive decline in the elderly. However, it's exciting to see scientists trying to find a fountain of youth, even if it's through THC. What a time to be alive.

Source: Gorzo-Bilkei A, Albayram O, Draffehn A et al. A chronic low dose of Δ9-tetrahydrocannabinol (THC) restores cognitive function in old mice. Nature Medicine. 2017.