JUST THE FACTS: Marijuana and Health
Marijuana is the subject of heated debate in our country. Despite one’s view on marijuana policy, it is
critical to be well-versed in the science.
Marijuana is one of the most misunderstood drugs of our time. Sifting through the rhetoric
about the drug can be difficult, but now we have a plethora of scientific studies from which to draw
firm conclusions about the use of the drug and its public health implications.
Marijuana and The Brain
Marijuana use directly affects the brain, specifically the parts of the brain responsible for
memory, learning, attention, and reaction time. These effects can last up to 28 days after abstinence
from the drug.1
Science confirms that the adolescent brain, particularly the part of the brain that regulates the
planning complex cognitive behavior, personality expression, decision making and social behavior, is
not fully developed until the early to mid-20s. Developing brains are especially susceptible to all of the
negative effects of marijuana and other drug use.2
What makes marijuana harmful? Three simple letters: T-H-C
Marijuana contains about 500 components, most of which we know little about. The most
prominent component is called THC. Scientists have found that THC is what produces the “high” users
experience. In today’s street marijuana, which is usually smoked, producers have increased THC levels
by more than four-fold3
, and reduced the natural levels of other components that have actually been
shown to reduce the high. Higher THC content can increase all of the usual negative effects of the
1
Hall W & Degenhard L (2009). Adverse health effects of non-medical cannabis use. Lancet, 374:1383-1391.
2
Giedd. J. N. (2004). Structural magnetic resonance imaging of the adolescent brain. Annals of
the New York Academy of Sciences, 1021, 77-85. And see
3
See, for example...