Does Smoking Marijuana Kill Brain Cells?

Marijuana is the most commonly abused illicit substance in the US, with 26 million Americans smoking pot at least once in 2008. Sixteen states now have legal medical marijuana programs as well.

Forty years ago, there were reports claiming that brain damage was caused by smoking marijuana. There were descriptions of marijuana smokers as lazy, apathetic, dull, delusional, irrational, and unproductive, which then gave reason for people to assume smoking marijuana resulted in brain damage.

As modern brain imaging was invented, such as CAT scans, no evidence of brain damage was seen in heavy chronic marijuana smokers. At Tulane Medical School in the 1970’s, animal studies were accomplished looking at massive doses of THC. Massive in these studies was 100 times the psychoactive doses in humans. The first set of studies showed significant EEG brain changes with implanted electrodes in monkeys. These changes, however, switched back to normal within one hour of drug administration.

Additional testing with the monkeys was not conclusive. On autopsy, however, there appeared to be some damage to the monkey’s hippocampus. In humans, this area is associated with intellectual function. The assumption then was that smoking marijuana by humans resulted in brain damage.

Years later, the Tulane study was done again in Arkansas at the National Center for Toxicological Research. Sixty four monkeys were evaluated in four groups: 1) Monkeys with high dose inhalation 2) Monkeys with low dose inhalation 3) Monkeys with placebo smoke and 4) Monkeys with no smoke inhalation. This time, the research showed no marijuana related brain abnormalities at all in any of the groups.

Based on previous scientific evidence, marijuana induced brain damage could not really be proven. That could be changing. There was a new study in late 2010 that showed potential for marijuana smoking to lower cognitive function.

In a paper presented meeting of the Society for Neuroscience, Dr. Staci Gruber, reported that in a small study of participants who began smoking pot before 16 years of age, they performed significantly worse on cognitive function tests than both non-smokers and those who became chronic smokers later in life.

This will need to be followed up with a larger study, as this may mean that when those with an immature nervous system start smoking marijuana there is the potential for long term vulnerability and brain effects.

Want to find out more about AZ medical marijuana, then visit Arizona MMC’s site on how to choose the best Arizona medical marijuana doctor for your evaluation.