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Cannabis reverses aging processes in the brain: Researchers at the University of Bonn are putting the memory of Methuselah mice back in their youth
The older we get, the more the ability to remember diminishes. In the course of a study, researchers from the University of Bonn and Hebrew University in Israel succeeded in reversing the aging processes in the brain in mice. Older animals could be restored to the state of two-month-old mice by prolonged low-dose treatment with a cannabis agent. This opens up new options for the treatment of dementia, for example. The results are now presented in the journal "Nature Medicine".
Our brain ages like any other organ. As a result, cognitive performance decreases with age. One notices this, for example, by the fact that it becomes more difficult to learn new things or to pay attention to several things at the same time. This process is normal, but can also promote dementia. Researchers have long been looking for ways to slow down or even reverse this process.
Scientists from the University of Bonn and the Hebrew University of Jerusalem (Israel) have now succeeded in doing this with mice. These animals have a relatively short lifespan in nature and already show strong cognitive deficits at the age of twelve months. The researchers administered a small amount of THC, the active ingredient of the hemp plant (cannabis), to mice at the age of two, twelve or 18 months over a period of four weeks.
They then tested the animals' ability to learn and memory - including, for example, the ability to orientate themselves and recognize other people. Mice given only one placebo showed natural age-related learning and memory loss. The cognitive functions of the cannabis-treated animals, on the other hand, were just as good as those of two-month-old control animals. "The treatment completely reversed the loss of performance of the old animals," reported Prof. Dr. Andreas Zimmer from the Institute for Molecular Psychiatry at the University of Bonn, member of the Cluster of Excellence ImmunoSensation.
Years of meticulous research
This treatment success is the result of years of meticulous research. First, the scientists found that the brain ages much faster when mice don't have a functional THC receptor. These so-called cannabinoid 1 (CB1) receptors are proteins to which substances dock and thereby trigger a signal chain. CB1 is also the reason for the intoxicating effect of THC in cannabis products, such as hashish or marijuana, that attach to the receptor. THC mimics the effects of the body's cannabinoids, which perform important functions in the brain. “With increasing age, the amount of cannabinoids naturally formed in the brain decreases,” says Prof. Zimmer. "If the activity of the cannabinoid system decreases, then we find a rapid aging of the brain."
To find out exactly what THC treatment does for old mice, the researchers examined the brain tissue and gene activity of the treated mice. The results were surprising: The molecular signature no longer corresponded to that of old animals, but was rather very similar to young animals. The number of connections between nerve cells in the brain also increased again, which is an important prerequisite for learning ability. "It looked as if the THC treatment had reset the molecular clock," says Zimmer.
Next step: clinical trial in humans
The dose of the administered THC was chosen so low that no intoxication was excluded in the mice. Cannabis products are already approved as medicines, for example for pain relief. In the next step, the researchers want to use a clinical study to investigate whether THC can also reverse the aging processes of the brain in humans and increase cognitive performance again.
The North Rhine-Westphalian Science Minister Svenja Schulze was enthusiastic about the study: "The funding of knowledge-based research is irreplaceable, because it is the breeding ground for all questions in application. It's a long way from mouse to human, but the prospect that THC could be used to treat dementia makes me extremely positive. ”(Sb)
Publication: A chronic low dose of delta9-tetrahydrocannabinol (THC) restores cognitive function in old mice, Nature Medicine, DOI: 10.1038 / nm.4311