Let's skip right to mea culpa: "Results indicate that previous studies of cannabis in youth may have overstated the magnitude and persistence of cognitive deficits associated with use."
What prompted this conclusion? Six Philadelphia-based researchers did a meta-analysis of 69 studies to examine the association between cannabis use and cognitive functioning in adolescents and young adults. The findings, published in the Journal of the American Medical Association - Psychiatry, suggested that heavy active users show a "small overall effect size for reduced cognitive functioning" regardless of current age or the age of first use. However, even these small reductions largely disappeared after 72 hours of abstinence.
To quote the researchers, "Studies requiring an abstinence period longer than 72 hours had an overall effect size that was not significantly different from 0." They also suggested the miniscule difference in cognition might simply reflect "residual effects from acute use or withdrawal."
Now for the Millennials out there who aren't hip to 1980s propaganda, imagine a scorching hot stove pan frying the fuck out of a recently cracked egg. This is how government ads aimed at youth characterized a person's brain when high on cannabis. Translating the famous "brain on drugs" ads into clinical terms, the bureaucrats argued that chronic cannabis consumption can cause permanent cognitive damage in developing brains.
Some prohibitionists still make this argument today, and while clinical assessments continue to evolve with more research, this study argues that earlier clinical claims "overstated" the risks. So instead of cooking your brain like an over hard egg, it appears cannabis doesn't even crack the shell. That makes "overstated" sound a lot like an understatement.