Rejuvenating Effects It may come as a surprise to some that science views the link between cannabis use and memory in a positive light. Did you know that THC improves learning and reverses age-related memory loss? A new study, conducted on mice, shows that THC may have rejuvenating effects on the brain. Find out how.
A new study on cannabis’s beneficial effects on health adds to its long list of benefits. At the beginning of May, a new study was published in the prestigious, specialist scientific journal Nature Medicine, conducted by a team of researchers from the University of Bonn, in Germany, and the Hebrew University of Jerusalem. The clinical trial, carried out on mice, shows that the main psychoactive ingredient of cannabis, cannabinoid delta-9-tetrahydrocannabinol or THC, may have positive rejuvenating effects on the brain, particularly with the elderly. It appears that THC, administered in low and regular doses, helps in enhancing learning and reverses age-related memory loss.
It will certainly come as a surprise to some that science views the link between cannabis use and memory in a positive light, given the much-touted argument that cannabis consumption is harmful to memory often used against it. This is all the more the case with a topic as controversial as our brain’s ageing. As we get older, we gradually lose our cognitive abilities, and learning new things or focusing on more than one thing at a time become tasks that are increasingly complicated.
The unstoppable passage of time
Despite countless scientific advances, there still remains a lot to be discovered and uncovered regarding biological mechanisms resulting in our body’s ageing process, both physically and mentally. As we age, the brain deteriorates and neurodegenerative diseases may arise, leading to memory loss or a diminished ability to focus attention and reason, amongst many other symptoms.
Over the centuries, science has tried to come up with a magic potion against ageing, an eternal fountain of youth, something that would help slow down or even reverse this inevitable process. It is still too early to find out exactly how cannabis could help in this quest. Nevertheless, the promising results of the study carried out by the researchers at the University of Bonn point in this direction: a small daily dose of THC could help protect our brain against the effects of ageing, by improving learning, memory or focus.
THC restores cognitive function depleted by ageing
At present, the laboratory tests confirming these findings have only been conducted on mice. The team plans to repeat these tests in humans in the future – but with purified THC which is easier for dosing – in order to see if the results of this study can be replicated. It looks as though we still have some way to go.
To carry out the clinical trial called “A chronic low dose of Δ9-tetrahydrocannabinol (THC) restores cognitive function in old mice”, the researchers administered low doses of THC to mice of various ages: 2, 12 and 18 months – in other words, young, mature and old mice. This was carried out regularly over four weeks. The dosage size is significant due to the fact such small doses do not have psychoactive effects such as those resulting from the amounts consumed for recreational use, which are usually greater.
Following a period of observation throughout this month, the team led by Professor Andreas Zimmer – director of the Institute of Molecular Psychiatry at the University of Bonn – and Professor Andras Bilkei-Gorzo of the institute, amongst others, are evaluating the mice’s ability to carry out cognitive tasks – such as water maze tests – to see if they can ascertain and recall the location of safe spots or recognise other subjects of the same species they have been exposed to previously.
The psychoactive phytocannabinoid protecting against brain ageing
Curiously, young rodents that had not been given low and regular doses of THC performed better in the behavioural tests for memory and learning than young mice treated with the said phytocannabidoid. On the other hand, the opposite was the case with older mice: the ones that had received low and regular doses of tetrahydrocannabinol had better results in the tests – which they performed in a shorter period of time and with better performance – than mature and old mice that had not been given any THC, and those given excessive doses.
Besides noting how cognitive performance seemed to have been significantly restored in old mice treated with THC in low doses, what the researchers found when examining these old mice was that more synaptic spines formed in the neurons located in the hippocampus, thus enhancing neuronal communication. Surprisingly, old mice treated with THC had a radically different pattern of gene expression in the hippocampus from old mice not treated with the phytocannabinoid.
The hippocampus is the area or main part of the brain that plays a key role in normal memory formation and activity in the long term, as well as learning. It is also closely linked to producing and regulating emotional states, as well as spatial memory. Throughout our lifetime, adults’ brains continue to create and form neurons, part of a process known as neurogenesis that occurs mainly in the hippocampus.
This area is one of the first to be affected by neurological diseases – such as dementia or Alzheimer’s, amongst others. This means people affected by these diseases experience a decline in their cognitive abilities, and frequently suffer from loss of memory, problems with focusing and orientation, difficulties communicating, and so on.
THC Interaction in the Endocannabinoid System
The results of the study clearly show the influence of THC on the brain due to its analogy with endocannabinoids, with which THC interacts when cannabis is consumed. The researchers found that this psychoactive compound, besides influencing the endocannabinoid system in mice, also helps restore its function.
This defence mechanism of the brain is controlled by the endocannabinoid system (ECS), a complex regulatory system in the body comprising a group of endogenous cannabinoid receptors, or endocannabinoids, located in the brains of mammals, as well as the central and peripheral nervous system. These are similar to the cannabis plant’s naturally occurring cannabinoids, known as phytocannabinoids.
As already discussed, the ECS plays a key role in our body’s physiological and pathological processes, and achieves this through a group of molecules known as receptors which interact and act as mediators in our nervous system’s intercellular communication. It is this endocannabinoid system that activates and coordinates the type of response the nervous system produces.
As for our brain, our immune system includes what are known as microglial and astrocyte cells, which help to repair and destroy harmful stimuli that can damage our neurons as we age.
As we get older, changes in the way our ECS functions may may occur, and this means microglia and astrocytes have an abnormal immune response, leading to a loss of neurons and inflammation in the part of the brain discussed above, the hippocampus, which is linked to memory.
What Zimmer and Bilkei-Gorzo’s team have clearly demonstrated with this study is that this phytocannabinoid, which the cannabis plant contains, restores cognitive function in older mice, by restoring the hippocampus to a state similar to those of young mice.
As the researcher Bilkei-Gorzo said: “There is a tiny difference between the distribution and action of the endocannabinoid systems of various mammals. There is some variation only in the density of cannabinoid receptors within the brain areas.”
A clinical trial which needs to be replicated in humans
Although it remains to be seen whether this study is clinically applicable to humans, to determine if the results can be replicated in humans, the researchers said in conclusion to their report that: “Regular treatment with low doses of THC or cannabis extract could be a potential strategy for slowing down or even reversing cognitive decline amongst the elderly.”
It is worth pointing out, however, that this is just one study amongst many others that have revealed cannabis’s potential and its rejuvenating effects on the brain, although at present only in mice. Despite the absence of toxicity observed in mice in these studies, there is still some way to go before they can be conducted on humans. This has been complicated by, amongst other things, the restrictions on cannabis due to its legal status.
It is nowadays impossible to ignore the many benefits of cannabis in the treatment of all manner of diseases, such as cancer, AIDS, multiple sclerosis, glaucoma, diabetes and a whole host of others. Cannabis has also proved useful in treating diseases of the brain, as well as acting as a neuroprotector capable of preventing brain diseases. The number of clinical trials on various cannabinoids and their therapeutic applications in neurology continue to grow. Let us hope science takes that decisive step.