Tetrahydrocannabinol or THC, the main psychoactive ingredient in marijuana, has been determined to make lab rats lazier and less willing to exert cognitive effort when compared to CBD or cannabidiol.

New findings come from a study published in the Journal of Psychiatry and Neuroscience, in which male rats were administered  THC, to measure its effects on the accomplishment of tasks that require mental and physical coordination. Researchers from the University of British Columbia, led by Mason Silveira, found out that the rats were always able to complete difficult tasks ahead of them, but just did not feel like it when being under the effects of THC.

Tetrahydrocannabinol. Image credit: https://www.royalqueenseeds.com

THC, the drug of laziness

The study comes from the increasing acceptance of cannabis as treatment and a recreational drug. It is estimated that each year, 11 percent of adults in the U.S. try marijuana fort the first time.

Marijuana DEA
Although the effects of THC are widely known in science, there is still need to further research CBD as it appears to regulate the effects of THC. Image credit: The Huffington Post.

The lack of CBD is paired with an increase in the levels of THC, which is an undesired psychoactive that can be removed to get rid of marijuana’s psychotic effects. Regular THC ingestion is able to cause anxiety and psychosis, while also causing depression as a symptom of abstinence.

The determining factor is that a reduced amount of CBD is equivalent to a higher level of THC. Because THC can impair cognitive processes, it was imperative to research its effects on decision-making.

Researchers pointed out that cannabis affects how an organism makes decisions based on risks and effort. There has already been some research proving that the willingness to apply physical effort is reduced when the subject is under the effects of THC, but there was no evidence suggesting that the same concept applies for cognitive effort until the latest study involving rodent cognitive effort tasks.

The research team aimed to understand how rats determined to be “workers” or “slackers” were affected by THC when it came to performing tasks with different levels of risk and reward. 

Rats on drugs

The rats were situated in a colony room with a day/night cycle. The subjects were tested in sessions of 30 minutes as they were presented with different levers that initiated trials designated as low-effort/low-reward and high-effort/high-reward. After pressing a lever, they would retract and the test would start.

On high-effort tasks, a light would flash for 0.2 seconds, while on low-effort tasks it would illuminate for 1 second. After turning off, the rats had 5 seconds to poke using their nose where the light had come from. For high-effort tasks, they would be rewarded with 2 sugar pellets, while low-effort tasks yielded only 1 sugar pellet.

Lab rats
Researchers measured the differences of the effects by taking into account the amount of THC weighed against the amount of CBD. Image credit: www.science.howstuffworks.com.

The rats were kept at 85 percent of their regular weight, which translates to a significant food restriction. After ending the test, the levers would appear again so the rats could start over again.

The test would not be rewarded if the rats did not do anything after the light flashed, if they showed impulsivity (responding after the set timers between action and reaction of the trials) and if they chose the wrong answer.

The rats were tested without the effects of drugs and under the effects of a placebo, THC, CBD, and both at the same time. Each set of tests occurred with one week in between each period to avoid pharmacology overlapping. The THC and CBD were administered 30 minutes before the tests.

Initially, the rats that chose high-effort tests 70 percent of the time were classified as “workers”, while the others were classified as “slackers.”

Consistently, the rats under the effects of THC always chose the low-effort task. This was true for all of the rats, regardless if they were classified as “workers” or “slackers.”

The rats did not suffer from a loss of accuracy because they could perform the trials correctly and consistently. What appeared to change was their willingness to produce a higher cognitive effort into trying to pay attention to the light flash that would indicate the test’s correct answer.

It was determined that CBD did not negate the psychoactive effects of THC, regardless of the amount administered. CBD is the compound that has been recognized as beneficial as it helps to treat epilepsy, chronic pain, and cancer.

This means that there has to be further research into developing strains of marijuana with increased levels of CBD and possibly none of THC, in order to avoid its psychoactive and impairing effects.

Although this still has to be proved on humans, it appears that THC has an important effect on cognitive effort. It is a critical finding, as marijuana must not have impairing side effects for it to gain more acceptance as a natural treatment for common ailments.

What’s interesting, however, is that their ability to do the difficult challenge was unaffected by THC. The rats could still do the task— they just didn’t want to,” stated Mason Silveira.

Source: University of British Columbia