Repost from the old site.
Fortunately for users, many of the most worst accusations against marijuana have not yet panned out. One of the most frightening is the specter of permanent brain damage. For instance, according to this site, marijuana:
affects, alters, and damages brain cells controlling thinking, emotion, pleasure, coordination, mood and memory. The pituitary gland is also damaged, which regulates hunger, thirst, blood pressure, sexual behavior, and release of sex hormones.Marijuana accumulates in the microscopic spaces between nerve cells in the brain called “synapses.”
This clogging interferes by slowing and impairing transfer critical information. Long term use causes the brain to stop production of brain chemicals necessary to “feel good” – a negative feedback condition. And, the user becomes chemically addicted to marijuana.
These studies may be related to the famous Heath monkey studies done in the 1970′s. A recent attempt by William Slikker in Arkansas and Charles Rebert and Gordon Pryor of Stanford Research Institute to replicate Heath was not able to replicate any of his frightening findings. There was no brain damage whatsoever in Slikker’s and the SRI Group’s monkeys.
In the early 1990′s, I conducted interviews with both Rebert and Pryor about these studies. At one point in the interview, an exasperated Rebert said, “Forget it. Cannabis is not neurotoxic.” Pryor had no explanation for the discrepancy between his findings Heath’s.
There is no evidence that THC “accumulates in synaptic gaps and clogs them up.” There is also no evidence that marijuana causes the brain to “stop producing feel good chemicals.” I am not sure where they are getting that one from. Recent studies show no long-term changes in brain chemicals from marijuana use.
Neither is there any evidence that, in a broad sense, cannabis causes “…damages brain cells controlling thinking, emotion, pleasure, coordination, mood and memory.” There is a possibility that cannabis use may impair the brain’s ability to winnow out extraneous stimuli to focus on one thing, but this is not yet proven. Nor is there any evidence of damage to the pituitary gland.
This post in its original form was far too long. I have decided to break it up into seven different posts, in addition to this post. The separate sections are listed below.
For an examination of the evidence of whether or not cannabis causes actual structural damage to brain cells, axons or dendrites, see here.
For an analysis of neuropsychological batteries of cannabis users to determine whether or not they suffer brain damage, see here.
For an analysis of EEG testing of cannabis users to discover evidence of brain damage, see here.
For an analysis of studies looking at cerebral blood flow in cannabis users, see here.
For an admittedly impressionistic analysis of whether or not cannabis causes schizotypal symptoms in users, see here.
For a summary comparing the effects of cannabis on the brain compared to other drugs, see here.
For a summary of the findings of cannabis and brain damage, see here.