Olga Khazan has a breezy, smart review of what we know (and mostly don’t know) about the effects of marijuana on the body:
It’s not good for your memory, at least if you start smoking as a teenager. In one study published in December, researchers examined teens who smoked marijuana daily for three years and found that the memory-related structures in their brains appeared
to “shrink and collapse inward,” and that they performed worse on memory tasks. The troubling thing? This was two years after the subjects stopped smoking. And the younger the teens were when they started lighting up, the worse the impairment seemed to be.
An earlier study in rats found that THC, the active ingredient in pot, weakened the connections between neurons in the hippocampus, the brain structure critical for memory formation. But an other study on human subjects found that the “skunk” strains of pot, which have a greater ratio of THC to cannabidiol, are worse for memory than hashish or herbal strains. And researchers who followed nearly 2,000 young Australian adults for eight years found that any differences in memory and intelligence between those who smoked pot and those who didn’t could also be attributed to gender or education, and the differences disappeared after the individuals stopped smoking.
There is evidence, though, that for older people, THC helps prevent against the brain inflammation that leads to Alzheimer’s disease.
My own take-away from this is that the first priority in dealing with marijuana is to prevent its use by teens. Prohibition has clearly failed to do that. And any new legal regime has to pass that test. My other conclusion is simply that we need much, much more research and that that research can only be done properly if the drug is re-classified. And yes, the idea that pot doesn’t affect memory is stupid. Of course it does. It’s not a panacea. And some memory loss is part of why it’s so attractive to human beings. Forgetting is a huge part of our survival as humans. Our brains could not function if they retained everything they absorb. What cannabis has done for humans for millennia is to ease the pain of memory, and liberate us ever so slightly from the past. That’s why it can be so helpful for some people with PTSD. A little oblivion is a far too under-rated thing.
The Dish 