New study shows effects of casually smoking marijuana

Excerpted from “Even casually smoking marijuana can change your brain, study says,” The Washington Post. April 16, 2014 — The days when people thought only heavy Cheech-and-Chong pot smokers suffered cognitive consequences may be over. A study in The Journal of Neuroscience says even casual marijuana smokers showed significant abnormalities in two vital brain regions important in motivation and emotion. “Some of these people only used marijuana to get high once or twice a week,” said co-author Hans Breiter, quoted in Northwestern University’s Science Newsline. “People think a little recreational use shouldn’t cause a problem, if someone is doing OK with work or school,” he said. “Our data directly says this is not the case.”


The study analyzed 20 pot smokers and 20 non-pot smokers between 18 and 25. Scientists asked them to estimate how much marijuana they smoked and how often they lit up over a three-month test period. Even those who smoked once a week showed brain abnormalities, while larger changes were seen in those who smoked more.

In the study, scientists compared the size, shape and density of the nucleus accumbens and the amygdala, which control emotion. Those who had smoked had abnormally large nucleus accumbens, an area of the brain that controls pleasure, reward, and reinforcement learning. In the brains of marijuana users, natural rewards are less satisfying.

Commentary

CMDA’s National Director of Campus & Community Ministries Dr. J. Scott Ries, MD: “Innocent until proven guilty...or dubious until proven safe?

“There is little dispute about the medical hazards of heavy marijuana use. What remain in question are the demonstrable potential effects of so-called ‘casual’ marijuana consumption.

“This study highlights apparent physical changes observed in the amygdala and nucleus accumbens of casual users compared to non-users. Granted, causality is not proven, but does it need to be for us to be concerned?

“Setting aside ‘legality,’ where does our duty begin with regard to caution of an unknown hazard? Should we, as those charged with advising the health of our patients, not demand evidence that such hazards are not present before acquiescing to the capricious eagre of our mercurial society?

“The most telling and scientifically accurate message should be that there is no known level of ‘safe’ recreational use of marijuana. Let us not retreat from wisely counseling our patients with Paul’s advice that while everything may be legal, everything is not good. “We are free to do all things, but there are things which it is not wise to do. We are free to do all things, but not all things are for the common good” (1 Corinthians 10:23, BBE).

Resources
Legalized recreation pot - A commentary from Dr. David Stevens
A five-part series on marijuana from Dr. Walt Larimore
The Effects of Marijuana, by Donal O’Mathuna