Like any other organ, our brain ages. As a result, cognitive ability also decreases with increasing age. This can be noticed, for instance, in that it becomes more difficult to learn new things or devote attention to several things at the same time. This process is normal, but can also promote dementia. Researchers have long been looking for ways to slow down or even reverse this process.
Weed smokers are usually characterised as bumbling paranoiacs incapable of remembering anything useful. But it turns out cannabis could actually boost the memories of older people and make their brain ‘younger’. A scientific study has found that feeding ganja to ageing mice boosted their brain power significantly. Researchers from the University of Bonn pumped THC, the chemical in weed which gets you stoned, into rodents of a certain age to find that a ‘chronic low dose restores cognitive function in old mice’.
What this means is that the mice were given a little bit of weed every day and it resulted in older animals performing as well in tests as younger competitors. ‘We treated old mice with a low dose of the active ingredient in cannabis,’ Andreas Zimmer, a professor at the Institute of Molecular Psychiatry, told Deutsche Welle.
‘Learning and memory functions improved dramatically in these animals, and they performed as well as mice that were much, much younger. ‘What we observed was quite staggering.’
To test their brain power, mice were tasked with finding a hidden platform. Normally, older mice would take longer to find the platform and remember where it was. But the stoned old rodents were able to perform just as well as the youthful whippersnappers.
The short-term effects of marijuana are generally felt within a few minutes, peak within 30 minutes, and wear off after about two or three hours. The bigger question is: what happens if we use marijuana more regularly, or are occasional but heavy users? Are there permanent cognitive and other health changes? Do we all turn into The Dude from the Big Lebowski?
Again, we don’t have many rigorous scientific studies on this, much less many longitudinal studies. A 2012 review of available research, however, published in the Journal of Addiction Medicine, finds that the immediate impairments on memory and concentration, at least, aren’t likely permanent:
Attention/concentration: Marijuana impairs light users’ attention and concentration but doesn’t appear to affect regular or heavy users within six hours of smoking or ingesting it. In the long run, researchers have found that after 3 weeks or more since last using marijuana, subjects’ attention and concentration return to normal. “In five of seven studies, no attention or concentration impairments were found in subjects who had remained abstinent from 28 days to one year.” The other two studies found differences in attention and concentration between heavy and non-users after 28 days, but the reviewers note that the disparate findings could be due to measuring different types of processing skills.
Working memory: Several studies likewise found no residual or long-term effects on working memory. A 2002 study, for example, tested 77 heavy smokers for days after abstaining from smoking pot. Memory impairment was found for heavy users up to 7 days after using marijuana, but by day 28 their memory test results didn’t differ significantly from control subjects. In other words, even if your memory is affected when you smoke up, after you stop it will likely go back to normal with time.
Health professionals and researchers (and lawmakers) on both sides of the debate continue to argue the pros and cons of marijuana use. As for us regular people, over a year ago, more than half of polled Americans said they were in favour of marijuana (recreational or medical) being sold legally, just like alcohol is.