People who are heavy cannabis users could have poorer working memory skills even if they haven't used the drug recently. Brain scans showed lower brain activation in several regions.

[u/mvea]

https://www.scimex.org/newsfeed/heavy-cannabis-use-could-have-a-lasting-effect-on-your-memory-skills

[u/PG-Noob]

Lifetime use # just seems like a weird metric for this or no? As you say, depending on the age of the person, the actual "heavyness" differs by a lot.

[u/UniqueUsername3171 → u/PG-Noob]

cumulative lifetime dose is an interesting metric used to guide the prescribing of corticosteroids

[u/Gooftwit → u/UniqueUsername3171]

Do canabinoids act like corticosteroids though?

[u/UniqueUsername3171 → u/Gooftwit]

tough to say; the receptors are colocalized in many tissues - meaning cells in those tissues have both receptors. We know CB1 and CB2 both mediate inflammation, as does the steroid receptor. so yes they’re very different things but the human body is so complicated it might not matter

[u/kodutta7 → u/Gooftwit]

How do you think we go about figuring that out?

[u/FavoritesBot → u/Gooftwit]

If the effect they are causing to memory cannot be healed, and there’s no minimum dose to cause the effect, then cumulative dose is probably right

[u/throwaway44445556666 → u/UniqueUsername3171]

Do you have any sources for this? Cumulative lifetime dose can help predict risk of osteoporosis, but I have never seen anyone take this into account when prescribing steroids. 

[u/UniqueUsername3171 → u/throwaway44445556666]

it’s taken into account for people who take steroids frequently, i.e. uncompliant/uncontrolled asthma. It’s not being considered when an otherwise healthy person get a medrol dose pack from their pcp for a head cold… reason being prednisone is often given in larger doses for longer periods of time.

[u/Ownfir → u/PG-Noob]

They use lifetime here bc the study is on working memory and if any past cannabis use affects working memory later in life (even if no longer actively partaking in it.)

[u/Turkishcoffee66 → u/PG-Noob]

It's standard practice with smoking. We measure use in pack-years, and it's turned out to be a better correlate for most smoking-related risk than other metrics.

So a 0.5 pack per day smoker x 40 years has a 20 pack-year history, as does a 2 ppd smoker of 10 years.

Whether cannabinoid exposure behaves similarly enough to the combustion products from smoking to justify measuring cumulative exposure is another matter, though.

Just wanted to give some context for why they may have chosen that type of measure. They're probably just trying to treat it like smoking to see if it works out.

[u/OtherwiseProgrammer9 → u/PG-Noob]

If there is cumulative damage then lifetime exposure is a better metric for it, just like tobacco smoking and exposure to other toxins like mercurium

[u/mleibowitz97 → u/PG-Noob]

It is kinda a weird metric, I agree. You gotta extrapolate the math out. But once a week for 18 years is still relatively heavy.

You could also theoretically smoke every day for 3-4 years and then stop for 9, and still be in "heavy".

Thats probably not super common though.

[u/Ghostrider556 → u/mleibowitz97]

Im curious about the study actually because I think the group that uses cannabis heavily for a few years and then quits is decently sized as a lot of us use it as teens a lot thru college years and then use drops off heavily. Im interested if in that scenario there are still meaningful effects later in life

[u/PhysicsCentrism → u/mleibowitz97]

For reference the average American drinks more than one standard drink a day on average.

So converting this to alcohol we’d be saying that if the average American cut back on drinking to 1/7 their current rate, they would still be a heavy drinker.

Heavy drinking is actually defined as: “NIAAA defines heavy alcohol use as follows: For men, consuming five or more drinks on any day or 15 or more per week For women, consuming four or more drinks on any day or eight or more per week SAMHSA defines heavy alcohol use for males as drinking five or more drinks on the same occasion (i.e., at the same time or within a couple of hours of each other) and for females as drinking four or more drinks on the same occasion on each of 5 or more days in the past 30 days.”

https://www.niaaa.nih.gov/alcohols-effects-health/alcohol-topics-z/alcohol-facts-and-statistics/glossary

[u/mleibowitz97 → u/PhysicsCentrism]

The average American is not the same as the median American, I feel like "one a day" is being skewed by alcoholics.

The rest I agree with, quite interesting.

[u/PhysicsCentrism → u/mleibowitz97]

I agree median is better, it’s also just harder to get from the quick google I did

[u/NickRick → u/mleibowitz97]

It is kinda a weird metric, I agree. You gotta extrapolate the math out. But once a week for 18 years is still relatively heavy.

i would argue no it isn't. for one, uses is a useless metric. and a heavy drinker is classified as having 15 doses a week, when they are calculating a heavy smoker is using 1-3 doses a week. also how much is a use? i use it every other day i eat a 2.5 mg edible, so 3.5 uses per week, is someone eating 2 500mg edibles a lighter user than me despite the fact it would take me 3+years to reach the same amount?

what this study does say is that people who self reported being heavy users performed worse on memory tests. and that don't take our study as casual because we couldn't account for other factors.

[u/Spez-S-a-Piece-o-Sht → u/PG-Noob]

My nephew, 23, is a massive pot head. I asked him on Christmas just how much he smokes, and he said he's been a daily smoker since he was 15 years old.

And yes, he's an absolute moron.