Cannabis could help treat Alzheimer's and dementia. Tetrahydrocannabinol (THC), the main active ingredient of the plant, would act against the aging of brain cells. Directed by Dr. Andras Bilkei-Gorzo, two teams of researchers from the University of Bonn in Germany and the Hebrew University of Jerusalem in Israel addressed the issue. Studies were conducted on mice to test the effects of THC on nerve cells. Research continues to determine whether cannabis can also affect the human brain. Meanwhile, the results of the studies were published in May 2017 in the journal Nature Medicine.

Low-dose cannabis dopes the brain of senior mice

For 28 days, the researchers studied two groups of mice, respectively 2 months old (nicknamed "young"), one year ("adults"), and 18 months ("old"). One group was injected with a low dose of THC each day, the other receiving only a placebo. After about a month, the effects of age and treatment on memory and space learning were evaluated by several tests, including the Morris maze (in which the mouse must remember the position of a platform inside a pool) and the speed at which they recognized familiar objects. The results of the study showed that mice called "old" and "adults" under THC obtained better results than their untreated comrades. "The treatment restored the cognitive capacities of " adult "and" old "mice (...) to the same level as those of" young "mice, under placebo, the researchers said.

The young rodents gave a poor performance

On the other hand, the "young" mice treated with THC performed very poorly, as might be expected. The destructive effects of THC on the learning of young brains are well known. The active substance would in fact act on the connection between the neurons, stimulated by THC, but also by restoring the expression of several genes, whose role is central to the good function of our memory. "These changes and associated cognitive improvements lasted several weeks after the end of treatment," the researchers saw it as a great potential. No side effects were observed in the treated mice.

According to Andras Bilkei-Gorzo, it is thanks to cannabis. He explained that the THC present in the plant "artificially active" the endocannabinoid system. It is the part of the brain that is dedicated to memory, mood and sensations. Stimulated by the natural component, the cells of the brain thus regain all their vitality.

Cannabis reversed the molecular clock

"The treatment has completely reversed the loss of performance in older animals," says one of the authors of the study, Professor Andreas Zimmer of the University of Bonn. After examining the brain tissue and gene activity in mice receiving THC, the researchers also found that their molecular signature (the set of proteins and genetic variations of the animal) no longer resembled that of older rodents, but showed similarities with that of young animals.

The number of neuronal connections in the brain, which play an important role in learning abilities, had also increased to a similar level as in the youngest mice. "It seems that the THC treatment reversed the molecular clock," Zimmer explains.

The beneficial effects of THC go even further. Autopsies performed on the brain tissue of the rodents revealed that their brain had rejuvenated. It is as if "THC treatment has reversed the molecular clock."

The researchers consider studies on human beings

The authors of the study intend to further their research. In particular, they want to test the effects of cannabis on the human brain. They would need volunteers, a good hundred of whom would be between 60 and 70 years of age.

Svenja Schulze, Minister for Science in the German Federal Government of North Rhine-Westphalia, is enthusiastic: "Even if the path is long between the mouse and the man, I am very optimistic about the possibility to use THC to treat dementia, for example ".

A relief for patients with Alzheimer's disease

The results of this next study could revolutionize the world of medicine. A study published in June 2016 had already found neuroprotective effects on cannabis, on neurons affected by the senile plaques characteristic of Alzheimer's disease (the most common form of dementia). It is by stimulating the cannabinoid receptors of the brain that the THC would act, advance the researchers. The rarefaction of these cells, natural with age, leads to accelerated cerebral aging but cannabis mimics the cannabinoids, thus ending the process.

Since the human brain has the same characteristics as mice, the work of German and Israeli scientists could ultimately give rise to a drug against dementia or Alzheimer's disease. The Independent interviewed psychiatrist Michael Bloomfield on the subject matter. "However, we are still in the early days, and further research in the future is needed," he warned, because "THC produces very complicated and sometimes conflicting effects depending on the dose administered, the age of the person or animal "or" the frequency of taking ".

Strong arguments for the legalization of cannabis and its therapeutic use

These new "therapeutic virtues" of cannabis will not fail to fuel the arguments in the numerous debates on its legalization and its therapeutic use. Meanwhile, many countries and several US states have recently relaxed their cannabis laws. The medical use of the substance, for example treating back pain, is gaining popularity everyday.