The short-term effects of smoking cannabis on cognition revealed by 69 studies on 2,100 cannabis smokers.
Heavy cannabis use does not have strong negative effects on memory or thinking skills, new research concludes.
The short-term intellectual effects of heavy pot use are minimal, the review of 69 studies including 2,100 pot users found.
Even the minimal effects quickly disappeared.
After abstaining from cannabis for 72 hours, young people’s cognitive skills were back to normal.
Dr J. Cobb Scott, who led the research, said:
“The length of abstinence was associated with how big the effect size was.
We don’t know if three days is a perfect cutoff for this.
We don’t know the maximum point at which abstinence might benefit cognitive functioning.”
The long-term effects of smoking cannabis are still unclear.
Teenagers could be at greater risk of psychosis or other problems as a result of long-term use.
Dr Scott said:
“The more you use cannabis, the more likely you are to have problems with cannabis, just like any other substance.”
People included in the 69 studies were between 18- and 30-years-old.
Smoking cannabis certainly had negative effects on cognition, but they were much smaller than expected.
Dr Scott said:
“It’s considered a small difference between groups, so the clinical significance of that is kind of questionable.
It does raise a question of how big are these differences in a practical sense, and what those differences mean in someone’s life.”
When young people stopped smoking cannabis their memory and thinking skills recovered from the slight deficit.
Dr Scott Krakower, a psychiatrist not involved with the study, said:
“They’re saying basically there’s not maybe as large of a difference in cognitive functioning, but they’re still saying there is potentially some cognitive dysfunction.
Even the smaller changes in cognitive function can still have long-lasting impacts on younger adults and adolescents.”
Dr Scott said:
“It’s important to think about the much longer-term effects of heavy use of cannabis, which this analysis doesn’t tell us that much about.”
The study was published in the journal JAMA Psychiatry (Scott et al., 2018).
