New research adds weight to the link between THC and a decrease in motivation
Margot Lespade | | News
For a while now, cannabis use has been linked to a range of behaviors sometimes called “amotivational syndrome” – or, to be completely blunt, laziness. But the evidence is mixed and many questions remain. Does low motivation pre-date cannabis use or does it contribute to the use of cannabis? If caused by cannabis, is it only associated with long-term use? Are these observed effects due to actual motivation or does cannabis affect motor performance? To add to the body of evidence, researchers examined the effects of oral THC on motivation in women – part of a wider study looking at the interaction between ovarian hormones and THC (1).
Participants were either administered 7.5 mg of THC, 15 mg of THC, or a placebo and then given a task that consisted of making repeated choices between a hard or easy task worth varying amounts of money. Results indicated that THC appeared to have dose-dependent acute amotivational effects, with THC participants showing preference for low-effort, low-reward tasks (less willingness to exert effort for rewards). To add to this, THC also affected the likelihood of completing tasks, though the authors note the result could be caused by lowered motor speed (hindering completion of trials), motivational effects (leading participants to abandon trials unfinished), or participants simply anticipating their failure to meet the demands of high-effort tasks.
With a women-only sample, the authors stressed the need for a direct comparison of sexes with the same design, to limit any effects of sex. They also recognize the limitation of their THC-only study and suggest that other cannabinoids present in whole-plant cannabis, like CBD, may potentially mitigate the impact of THC on motivation (2). As for the future, the authors suggest that further research is needed to explore i) the combined effects of CBD and THC on willingness to exert effort, and ii) the impact of different administration routes.
Though this study did not examine the long-term effects of cannabis, the results point to chronic and heavy cannabis users experiencing amotivational effects in everyday life – potentially leading to an overall lower quality of life. Therefore, the team calls for medical professionals to take these results into account, especially when treating individuals with cannabis use disorder.
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- Wardle et al., Psychopharmacology (2022). DOI: 10.1007/s00213-021-06032-1
- Lawn et al., Psychopharmacology (2016). DOI: 10.1007/s00213-016-4383-x