We've written a number of times about the advantages that cannabinoids can bring - how they can become effective pain killers even without the high, how they don't harm the lungs when smoked, and many more. But marijuana is definitely not a substance you want to abuse, just like tobacco and alcohol. In many cases, it can prolong and spread pain, and when consumed in significant quantities, on a regular basis, it has important negative effects on the brain.
Teenagers and youngsters who smoked marijuana daily (or several times a week) for three years or more performed poorly on memory tasks and showed abnormal changes in their brain structure, according to a Northwestern Medicine study. Furthermore, the brain abnormalities were observed 2 years after the individuals stopped smoking, apparently indicating long lasting, chronic effects of smoking marijuana. Memory-related structures in their brains appeared to have a strange development shrinking and collapsing inward, potentially indicating a decrease in neurons and/or neural paths.
“The study links the chronic use of marijuana to these concerning brain abnormalities that appear to last for at least a few years after people stop using it,” said lead study author Matthew Smith, an assistant research professor in psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine. “With the movement to decriminalize marijuana, we need more research to understand its effect on the brain.”
The study also highlighted the similar poor memory performance in marijuana smokers and schizophrenics. This isn't to say that they experience the same symptoms or anything like this, just that there are similarities in terms of memory performance; the point they make here is that since both the substance and schizophrenia affect the same areas of the brain, people suffering from this disease should really avoid smoking weed.
The main downside of this study, as I see it, is that it only analyzes a single point in time. Sure, it seems to indicate long lasting (if not permanent) damage to the brain caused by marijuana, but a study with a bigger time frame is needed in order to better understand the effects of the substance on the brain. This study is one of the first to analyze these effects on the deep regions in the brain, and it is actually the first one to focus on the working memory.
“A tremendous amount of addiction research has focused on brain regions traditionally connected with reward/aversion function, and thus motivation,” noted co-senior study author Hans Breiter, M.D., professor of psychiatry and behavioral sciences and director of the Warren Wright Adolescent Center at Feinberg and Northwestern Memorial. “This study very nicely extends the set of regions of concern to include those involved with working memory and higher level cognitive functions necessary for how well you organize your life and can work in society.”
Personally, I wish both the positive and the negative effects of marijuana would have been studied long ago, but sadly, this is very hard to do for scientists from a legislative point of view... for whatever reason.