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. Under normal circumstances, most rats preferred the harder challenge to earn a bigger 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. “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 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.
– 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.)