THC, the main psychoactive ingredient in cannabis, makes rats less willing to exert cognitive effort – lazy – but, you know, that’s just, like, your opinion, man 
 
 The main psychoactive ingredient in marijuana makes lab rats lazy, according to University of British Columbia researchers. 
 
 The new research, published on Tuesday in the Journal of Psychiatry and Neuroscience, looked at the effects of both THC – the drug’s main active ingredient – and the non-psychoactive compound cannabidiol, or CBD, on the male lab rats’ willingness to exert cognitive effort. 
 
 What are the true risks of taking cannabis? Read more 
 
 Researchers trained 29 rats on two different challenges: rats which successfully carried out the more difficult task earned two sugar pellets; those which carried out the easier task earned just one. 
 
 Rats usually preferred the harder, but more rewarding, task. But after being dosed with THC, the same rats picked the easier task. 
 
 CBD, which does not cause a high and is believed to have medicinal benefits such as relieving pain and the symptoms of epilepsy, had no impact on the rats’ cognitive behaviour. It also did not mitigate the cognitive impact of THC in the rats. 
 
 
 
 The THC did not make the rats less intelligent – just lazier, said the study’s lead author, Mason Silveira, a PhD candidate in psychology at the University of British Columbia. 
 
 
 
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 “When rats were given THC – the active ingredient in cannabis or marijuana – we found that they were less likely to exert the mental energy needed to do more difficult tasks,” he said. 
 
 
 
 “What’s particularly interesting is though they were less likely to do these more difficult tasks they were still able to. There’s this distinction between THC’s ability to affect your cognition versus your willingness to actually use your cognitive abilities.” 
 
 
 
 Silveira said his work underscores the need for more research to determine the impact of THC on the human brain, to explore how any of those potential negative effects could be mitigated, and to look into the effect of other marijuana compounds other than CBD on THC’s impact. 
 
 
 
 “Our research highlights that, yes, cannabis itself may be beneficial for a variety of things, but can maybe lead to these impairments in cognition that you might want to consider,” he said. 
 
 
 
 A 2012 report by the Canadian Centre on Substance Abuse said there was “sound evidence” from both animal and clinical trials that medicinal marijuana can offer relief of nausea and vomiting and certain types of pain, but warned there was a lack of research documenting the risks associated with the medical use of cannabis. 
 
 ||||| Starting in 1996, Alexa Internet has been donating their crawl data to the Internet Archive. Flowing in every day, these data are added to the Wayback Machine after an embargo period. ||||| THC makes rats lazy, less willing to try cognitively demanding tasks: UBC study 
 
 New research from the University of British Columbia suggests there may be some truth to the belief that marijuana use causes laziness— at least in rats. 
 
 The study, published today in the Journal of Psychiatry and Neuroscience, found that tetrahydrocannabinol (THC), the main psychoactive ingredient in marijuana, makes rats less willing to try a cognitively demanding task. 
 
 “Perhaps unsurprisingly, we found that when we gave THC to these rats, they basically became cognitively lazy,” said Mason Silveira, the study’s lead author and a PhD candidate in UBC’s department of psychology. “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.” 
 
 For the study, researchers looked at the effects of both THC and cannabidiol (CBD) on rats’ willingness to exert cognitive effort. 
 
 They trained 29 rats to perform a behavioural experiment in which the animals had to choose whether they wanted an easy or difficult challenge to earn sugary treats. 
 
 Under normal circumstances, most rats preferred the harder challenge to earn a bigger reward. But when the rats were given THC, the animals switched to the easier option, despite earning a smaller reward. 
 
 When they looked at the effect of CBD, an ingredient in marijuana that does not result in a high, researchers found the chemical did not have any effect on rats’ decision-making or attention. CBD, which is believed to be beneficial in treating pain, epilepsy and even cancer, also didn’t block the negative effects of THC. 
 
 “This was surprising, as it had been suggested that high concentrations of CBD could modulate or reduce the negative effects of THC,” said Catharine Winstanley, senior author of the study and an associate professor in UBC’s department of psychology. “Unfortunately, that did not appear to be the case.” 
 
 Given how essential willingness to exert cognitive effort is for people to achieve success, Winstanley said the findings underscore the importance of realizing the possible effect of cannabis use on impairing willingness to engage in harder tasks. 
 
 While some people view marijuana as a panacea that can cure all ailments, the findings also highlight a need for more research to determine what THC does to the human brain to alter decision-making. That could eventually allow scientists to block these effects of THC, allowing those who use medical marijuana to enjoy the possible benefits of cannabis without the less desirable cognitive effects. 
 
 METHOD 
 
 At the beginning of each behavioural experiment, rats chose between two levers to signal whether they wanted an easy or hard challenge. 
 
 Choosing the easy challenge resulted in a light turning on for one second, which the rats could easily detect and respond to by poking it with their nose, receiving one sugar pellet as a reward. In the more difficult challenge, the light turned on for only 0.2 seconds, rewarding the rat with two sugar pellets if they responded with a nose poke.
– Scientists, apparently bored with pert, productive rats, added a little marijuana to the equation and found that, as many a teenager can tell you, laziness ensued. So report researchers at the University of British Columbia in the Journal of Psychiatry and Neuroscience after concluding that male lab rats given TCH experience an observable reduction in their "willingness to exert cognitive effort." To test this, researchers trained 29 rats to choose whether they wanted to perform a more difficult task to earn a larger quantity of a sugary treat or perform an easier task but earn less of the treat. Without THC, most of the rats preferred to exert themselves for the greater reward; after the dose of THC, however, they largely chose the easier path and settled for a smaller treat, even though their ability to perform the harder task was not impacted. "What’s particularly interesting is though they were less likely to do these more difficult tasks they were still able to," one researcher tells the Guardian, adding that there's a clear need for more research on how THC impacts the human brain, whether any negative side effects can be reduced, and whether marijuana compounds other than THC play a role. When the researchers gave the rats doses of the non-psychoactive compound cannabidiol, or CBD, which is thought to have medical benefits such as pain relief and doesn't cause a high, they found that it didn't impact the rats' cognitive behavior, but it also didn't help mitigate the effects of THC on motivation. (Here's what a legal pot habit will set you back just south of the border in Washington state.)