Jacobs says it could be that HU210 and THC do not have the same effect on cell growth. It could also be the case that cannabinoids behave differently in different rodent species – which leaves open the question of how they behave in humans.
They found that giving rats high doses of HU210 twice a day for 10 days increased the rate of nerve cell formation, or neurogenesis, in the hippocampus by about 40%.
In another study, Barry Jacobs, a neuroscientist at Princeton University, gave mice the natural cannabinoid found in marijuana, THC (D9-tetrahydrocannabinol)). But he says he detected no neurogenesis, no matter what dose he gave or the length of time he gave it for. He will present his results at the Society for Neuroscience meeting in Washington DC in November.
When the rats who had received the cannabinoid were placed under stress, they showed fewer signs of anxiety and depression than rats who had not had the treatment. When neurogenesis was halted in these rats using X-rays, this effect disappeared, indicating that the new cell growth might be responsible for the behavioural changes.
Just like Prozac?
A synthetic chemical similar to the active ingredient in marijuana makes new cells grow in rat brains. What is more, in rats this cell growth appears to be linked with reducing anxiety and depression. The results suggest that marijuana, or its derivatives, could actually be good for the brain.
In mammals, new nerve cells are constantly being produced in a part of the brain called the hippocampus, which is associated with learning, memory, anxiety and depression. Other recreational drugs, such as alcohol, nicotine and cocaine, have been shown to suppress this new growth. Xia Zhang of the University of Saskatchewan in Saskatoon, Canada, and colleagues decided to see what effects a synthetic cannabinoid called HU210 had on rats’ brains.
A previous study showed that the antidepressant fluoxetine (Prozac) also increases new cell growth, and the results indicated that it was this cell growth that caused Prozac’s anti-anxiety effect. Zhang wondered whether this was also the case for the cannabinoid, and so he tested the rats for behavioural changes.
Zhang says more research is needed before it is clear whether cannabinoids could some day be used to treat depression in humans.
That same study found that the most significant factor was when those participants began using marijuana. Those who started smoking as adults rather than teenagers faced no decrease in IQ. Adolescents with their still-developing brains have the most to lose cognitively. Rather than killing off brain cells, however, marijuana impedes brain development, putting young adults at a number of neurocognitive deficits (the human brain isn’t fully developed until age 25).
The younger a person starts using, the greater the reduction of their brain size—the prefrontal cortex specifically). While there is still much to understand about the specific parts of the juvenile brain that are impacted and why, many other drug studies have shown that younger introduction to drug use can make individuals more prone to mental illness and addiction, in addition to cognitive impairment.
This system that marijuana is able to exert influence on is known as the endocannabinoid (EC) system. It affects virtually every part of the brain, including the amygdala (emotion regulation), brain stem (pain sensitivity), and hypothalamus (hunger and sexual impulses), all of which are responsible for those hallmark signs of a marijuana high.
What are the side effects that come to mind when you think of marijuana use? Most likely giggling, slowed speech and movements, and a sudden craving for snacks. This bumbling stereotype might lead you to believe that marijuana makes you dumber, but the scientific consensus seems to be that marijuana does not kill brain cells. This doesn’t mean that marijuana is harmless, however.
4 Ways That Marijuana Affects Cognition
While weed doesn’t directly result in the death of the neurons the way that stress, head trauma, or other types of substances can, it can still go on to cause significant—and long-lasting—damage. This brain damage can lead to permanent side effects such as impaired memory, mental illness, and in the case of adolescents and their still-developing brains, a lower IQ.
Any type of prolonged use of a psychoactive substance has the potential to cause neurological imbalances or impairment—and marijuana is no exception. The exact nature and extent of brain damage or other lasting effects can depend on a number of factors including:
A New Zealand study involving over 1,000 teenagers had them take an IQ test at age 13 and then again at age 38 and also inquired as to their drug use habits. The study found that those who used marijuana at least four times a week experienced an average IQ drop of 8 points during this period. This experiment is the first of its kind to confirm that marijuana usage can directly contribute to loss of intelligence. The results also highlight the significance of frequency when it comes to the likelihood of severe or lasting side effects. However, there was one finding that overshadowed all the rest…
How Marijuana Works
Though marijuana may not be as overtly damaging as alcohol, meth, or cocaine (substances that drastically alter brain chemistry and uncoincidentally, are highly addictive), there are still plenty of undesirable cognitive side effects to be had.
Although this phenomenon isn’t exclusive to weed smokers, they do face the greatest risk. Approximately 15% of marijuana users experience these psychotic symptoms (otherwise known as a “bad high”). Most will only experience these adverse side effects while intoxicated, but others go on to find themselves permanently afflicted, which would then fall under the label of a true drug-induced mental illness.