You know those really, really smart kids in high school that smoked pot all the time? Yeah, me neither. There might be a pretty good reason for that, a recent study shows. 

Smoking pot during your adolescent yeras may lower your IQ, which is pretty easy to believe. However, it doesn't say anything about AFTER your teens, and what's done is done, so go ahead and indulge in that third blunt. Now way THAT will make you dumber, is there? 

More than 1,000 study participants from New Zealand were tested for IQ at age 13 - likely before any significant marijuana use - and again at age 38.

In addition to IQ tests, participants were given five interviews between ages 18 and 38, including questions related to their marijuana use.

Researchers compared their IQ scores at age 13 to the score at age 38 and found a drop only in those who had started regularly smoking pot by 18. Those deemed marijuana-dependent in three or more surveys had a drop averaging 8 points. If a person had average intelligence and was smarter than 50 percent of the population, dropping 8 points would give them a score only higher than 29 percent of the population, the researchers said.

Among participants who'd been dependent at 18 and in at least one later survey, quitting didn't remove the problem. IQ declines showed up even if they'd largely or entirely quit using pot at age 38, analysis showed.

So, assuming all the methods are sound...weed makes you dumb. 

Big win for science today, folks.