How Smoking Pot Every Day Really Affects Your Memory

Illustrated by Marcel George.
Stoners have long suffered horrible jokes about their (possibly horrible) memory, but is there any truth to the connection? New research suggests there is — but it's probably not as big of a deal as you think. For the study, published online this week in JAMA Internal Medicine, the researchers looked at data for 3,385 people from 1986 to 2011. At the beginning of the study, everyone was between the ages of 18 to 30. Over the years, the researchers kept track of each participant's marijuana use and overall health. Then, 25 years later, in 2011, the participants also went through a verbal memory test, in which they had to remember 15 words. In addition, they took tests that measured their problem-solving speed and ability to focus on the task at hand. Results showed that 84% of the participants reported using marijuana at some point in their lives, but most of them weren't smoking regularly for very long. Only 392 participants (about 12%) reported still using weed in middle age, and only 311 (8%) had at least five years of pot use. Those who had recently used marijuana at the 25-year follow-up tended to have poorer scores on the word memory and problem-solving speed tests, but those who had used more marijuana throughout the course of their entire lifetimes only had worse scores on the memory task. Specifically, for every five years of daily marijuana use, people did worse on the memory test. What this suggests is that being a current user of marijuana might actually matter more for your memory and problem-solving skills than how much you've smoked over your lifetime —though bombing a memory test isn't great news either.
But that brings up another point: Just how poorly did they do on the test? The people who used marijuana throughout their lives were unable to remember one half of one of those 15 words. Or, more accurately, half of them couldn't remember one whole word. While the effect does seem real, this isn't exactly the significant memory loss you might expect after five years of smoking pot daily — especially considering those participants did fine on the other tests. However, as The Washington Post points out, that memory lapse can certainly add up with continued daily weed use. If you're smoking every single day for 25 years, you can expect to not remember at least two of those 15 words, according to this study. Still, this is hardly the stuff of 'Reefer Madness,' and it also adds a twist to previous findings about marijuana's effects on the brain. It's also worth noting that because of the study's design, we can only tell that the drop in memory is associated with marijuana use — we can't tell for certain that weed is causing that effect. We'll still need more research before we really know the impact of your college smoking sessions.

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