It is difficult to determine how long the effects of cannabis last as different people provide different answers. This poses a problem when trying to ascertain how long a patient using cannabis for medical purposes will remain impaired.
In 2021, a meta-analysis of 80 papers was conducted to narrow down the timeframe. According to scientists, the duration of impairment depends on factors such as the method of consumption and the potency of the cannabis. The user may remain impaired for a period ranging from three to ten hours.
The text highlights the discrepancy between the detection of THC in the body and the actual period of impairment caused by cannabis consumption. Psychopharmacologist Iain McGregor suggests that legal frameworks need to be updated to focus on the interval when users are more of a risk to themselves and others, similar to laws surrounding alcohol consumption. He argues that prosecuting solely on the basis of the presence of THC in blood or saliva is unjust.
The following text has been reviewed and revised to make it clearer and correct any errors:
A meta-analysis is a type of research study that involves reviewing and analyzing a wide range of scientific literature. It aims to cross-reference the results from various studies to arrive at a conclusion based on a broader array of methodologies and subjects, such as people than what can be covered in a single study.
A team led by USYD nutritionist Danielle McCartney conducted the first-ever meta-analysis of its kind on impairment caused by tetrahydrocannabinol (THC), the compound in cannabis that causes intoxication. The team analyzed 80 different studies on this topic.
The team studied 1,534 “performance outcomes” from people who had consumed cannabis, evaluating their driving and cognitive abilities at various time intervals after consumption. The duration of impairment depended on three main factors: the strength of the THC dose, the method of consumption (inhaled or taken orally), and the frequency of cannabis use (occasional or regular).
“Our analysis indicates that impairment may last up to 10 hours if high doses of THC are consumed orally. A more typical duration of impairment, however, is four hours, when lower doses of THC are consumed via smoking or vaporization and simpler tasks are undertaken,” McCartney said.
“This impairment may extend up to six or seven hours if higher doses of THC are inhaled and complex tasks, such as driving, are assessed.”
It’s interesting to note that after consuming the same amount of cannabis on a regular basis, regular users can develop a tolerance and outperform occasional users on cognitive tasks. Since frequent users may require higher dosages to achieve the same level of intoxication as occasional users, it is difficult to predict how much or how long cannabis will impair them.
“We found that impairment is much more predictable in occasional cannabis users than regular cannabis users,” explained USYD behavioral pharmacologist Thomas Arkell.
“Heavy users show significant tolerance to the effects of cannabis on driving and cognitive function, while typically displaying some impairment.”
According to a study, it takes about five hours for most driving-related skills to return after inhaling cannabis. However, the exact time may differ for regular users, so more research is needed to determine the effects of THC in general. Once this research is completed, it can be used to help guide legislation. The researchers emphasized the importance of having this information to better understand the effects of cannabis use.
“Laws should be about safety on the roads, not arbitrary punishment,” McGregor said. “Given that cannabis is legal in an increasing number of jurisdictions, we need an evidence-based approach to drug-driving laws.”
This news is a creative derivative product from articles published in famous peer-reviewed journals and Govt reports:
References:
1. McCartney, D., Arkell, T. R., Irwin, C., & McGregor, I. S. (2021). Determining the magnitude and duration of acute Δ9-tetrahydrocannabinol (Δ9-THC)-induced driving and cognitive impairment: A systematic and meta-analytic review. Neuroscience & Biobehavioral Reviews, 126, 175-193.
2. Anderson, Beth M., et al. “Sex differences in the effects of marijuana on simulated driving performance.” Journal of psychoactive drugs 42.1 (2010): 19-30.
3. Anderson, Beth M., et al. “Sex, drugs, and cognition: effects of marijuana.” Journal of psychoactive drugs 42.4 (2010): 413-424.
4. Arkell, Thomas R., et al. “Cannabidiol (CBD) content in vaporized cannabis does not prevent tetrahydrocannabinol (THC)-induced impairment of driving and cognition.” Psychopharmacology 236 (2019): 2713-2724.
5. Arkell, Thomas R., et al. “Effect of cannabidiol and Δ9-tetrahydrocannabinol on driving performance: a randomized clinical trial.” Jama 324.21 (2020): 2177-2186.