Facts
Marijuana
Usually
smoked as a cigarette or joint, or in a pipe or bong, marijuana has appeared in
"blunts" in recent years. These are cigars that have been emptied of
tobacco and re-filled with marijuana, sometimes in combination with another
drug, such as crack. Some users also mix marijuana into foods or use it to brew
tea.
The
main active chemical in marijuana is THC (delta-9-tetrahydrocannabinol).
Short-term effects of marijuana use include problems with memory and learning;
distorted perception; difficulty in thinking and problem-solving; loss of
coordination; and increased heart rate, anxiety, and panic attacks.
Health
Hazards
Effects of Marijuana on the Brain.
Researchers
have found that THC changes the way in which sensory information gets into and
is acted on by the hippocampus. This is a component of the brain's limbic system
that is crucial for learning, memory, and the integration of sensory experiences
with emotions and motivations. Investigations have shown that THC suppresses
neurons in the information-processing system of the hippocampus. In addition,
researchers have discovered that learned behaviors, which depend on the
hippocampus, also deteriorate.
Effects on the Lungs.
Someone
who smokes marijuana regularly may have many of the same respiratory problems
that tobacco smokers have. These individuals may have daily cough and phlegm,
symptoms of chronic bronchitis, and more frequent chest colds. Continuing to
smoke marijuana can lead to abnormal functioning of lung tissue injured or
destroyed by marijuana smoke.
Regardless
of the THC content, the amount of tar inhaled by marijuana smokers and the level
of carbon monoxide absorbed are three to five times greater than among tobacco
smokers. This may be due to marijuana users inhaling more deeply and holding the
smoke in the lungs.
Effects of Heavy Marijuana Use on Learning and Social Behavior.
A
study of college students has shown that critical skills related to attention,
memory, and learning are impaired among people who use marijuana heavily, even
after discontinuing its use for at least 24 hours. Researchers compared 65
"heavy users," who had smoked marijuana a median of 29 of the past 30
days, and 64 "light users," who had smoked a median of 1 of the past
30 days. After a closely monitored 19- to 24-hour period of abstinence from
marijuana and other illicit drugs and alcohol, the undergraduates were given
several standard tests measuring aspects of attention, memory, and learning.
Compared to the light users, heavy marijuana users made more errors and had more
difficulty sustaining attention, shifting attention to meet the demands of
changes in the environment, and in registering, processing, and using
information. The findings suggest that the greater impairment among heavy users
is likely due to an alteration of brain activity produced by marijuana.