Cannabis may ward off dementia

It is illegal in Australia, but researchers from the Universities of Bonn and Mainz in Germany have discovered cannabis, also known as marijuana, could help protect the brain from ageing.

In experiments with mice, researchers claimed they switched off the ‘cannabinoid-1 receptor’; and as a result, the animals showed rapid signs of degeneration – as seen in people with dementia.

The research results, presented in this month’s journal Proceedings of the National Academy of Sciences (PNAS), suggested the factors controlling degenerations of the brain are still mostly unknown as humans become older and the number of people with dementia increases.

However, researchers predicted factors such as stress, accumulation of toxic waste products,  as well as inflammation, accelerate the ageing process. But, alternately, there are also mechanisms that can – like a bodyguard – protect the brain from degenerating, or repair defective structures.

The previously unknown function of the cannabinoid-1 receptor (CB1) was reportedly discovered in this study. A receptor is a protein that can bind to other substances, triggering a chain of signals.

Cannabinoids, such as THC – the active agent in cannabis sativa – and endocannabinoids are formed by the body bound to the CB1 receptors. The existence of this receptor is also the reason for the intoxicating effect of marijuana.

“If we switch off the receptor using gene technology, brains of mice age much faster,” Önder Albayram, principal author, said. “This means the CB1 signal system has a protective effect for nerve cells.”

The researchers studied mice in different age categories – young six-week-old animals, middle-aged ones at five months, and those of an advanced age at 12 months. The rodents had to master various tasks; beginning with having to find a submerged platform in a pool.

Once the mice knew its location, the platform was moved, and the rodents had to find it again. This was how the researchers tested how well the rodents learned and remembered.

The mice in which the CB1 receptor had been switched off (the knock-out mice) clearly differed from their kind.

“The knock-out mice showed clearly diminished learning and memory capacity,” the study’s authors said.

So, animals that did not have the receptor were less successful in their search for the platform. “In addition, they showed a clear loss of nerve cells in the hippocampus; which is the central area of the brain for forming and storing information,” they explained.

In addition, the researchers found inflammation processes in the brain. As the mice advanced in age, the degenerative processes became increasingly noticeable.

The animals with the intact CB1 receptor, to the contrary, clearly did better with regard to their learning and memory capabilities, as well as the health of their nerve cells.

The researchers said the study had begun to open the door to solving the root cause of ageing. The processes in the rodents’ brains had a surprising number of parallels with age-related changes in human brains. So, the endocannabinoid system may also present a protective mechanism in the ageing of the human brain.

However, the principal author indicated additional research was required to better understand the mechanism by which CBI receptors protect the brain from inflammation processes; and based on these signal chains, it might then be possible to develop substances for new therapies.