170 CHAPTER 4
from the leaves and flowers of the hemp plant called Cannabis sativa. (Hashish is the con-
centrated substance made by scraping the resin from these leaves, and both marijuana
and hashish contain cannabinoids.) The most psychoactive cannabinoid, and the active
ingredient in marijuana, is tetrahydrocannabinol (THC). Marijuana is best known for its
ability to produce a feeling of well-being, mild intoxication, and mild sensory distor-
tions or hallucinations.
The effects of marijuana are relatively mild compared to those of the other hal-
lucinogens. In fact, an inexperienced user who doesn’t know what to expect upon
smoking that first marijuana cigarette may feel nothing at all. Most people do report
a feeling of mild euphoria and relaxation, along with an altered time sense and
mild visual distortions. Higher doses can lead to hallucinations, delusions, and the
all-too-common paranoia. Most studies of marijuana’s effects have concluded that
while marijuana can create a powerful psychological dependency, it does not pro-
duce physical dependency or physical withdrawal symptoms (Gordon et al., 2013).
However, after alcohol and nicotine, cannabis dependence is the most common form
of drug dependence in the United States, Canada, and Australia (Hall & Degenhardt,
2009). Even at mild doses, it is not safe to operate heavy machinery or drive a car
while under the influence of marijuana because it negatively affects reaction time
and perception of surroundings; the drug reduces a person’s ability to make the split-
second decisions that driving a car or other equipment requires. Information process-
ing in general, attention, and memory are all likely to be impaired in a person who
has used marijuana.
Marijuana is most commonly smoked like tobacco, but some people have been
known to eat it baked into brownies or other foods. This is a kind of double duty for the
doctored food, as marijuana stimulates the appetite.
Although no one has ever been known to die from an overdose of marijuana,
smoking it is not a healthy habit. Research linking marijuana smoking and lung can-
cer is not definitive due to the fact that many studies have not been able to control for
confounding variables, such as cigarette smoking, alcohol use, or other risk factors
(Berthiller et al., 2008; Hall & Degenhardt, 2009). to Learning Objective 1.9.
Aside from those previously mentioned, probable adverse effects from chronic
nonmedical marijuana use also include increased risk of motor vehicle crashes,
chronic bronchitis or other lung problems, and cardiovascular disease. In adoles-
cents who are regular users, psychosocial development, educational attainment, and
mental health can be negatively impacted (Borgelt et al., 2013; Gordon et al., 2013;
Hall & Degenhardt, 2009; Hirvonen et al., 2011; Madras, 2014). With regard to the
possible mental health problems, there especially appears to be an increased risk for
psychotic symptoms and disorders later in life for adolescents who are regular and
heavier users (Hall & Degenhardt, 2009; Hirvonen et al., 2011; Madras, 2014; Moore
et al., 2007).
There are some legitimate medical uses for marijuana, and 25 states and the District
of Columbia have legalized medical marijuana since 1996 (Hasin et al., 2015). Aside from
uses in treating the nausea resulting from chemotherapy for both cancer and autoim-
mune deficiency disease (AIDS), medical marijuana has either proven useful or is show-
ing great promise in treating chronic pain, depression, and posttraumatic stress disorder,
for example (Greer et al., 2014; Haj-Dahmane & Shen, 2014; Ware et al., 2015). Despite
fears that availability of medical marijuana would lead to an increase of marijuana
use among adolescents, studies over the past 24 years have found no evidence of such
increases (Hasin et al., 2015; Johnson et al., 2015).
Ta b l e 4. 5 summarizes the various types of drugs, their common names, and their
effects on human behavior.This is a medical marijuana dispensary
in Ypsilanti, Michigan. How might having
marijuana available in such legal stores
change the illegal drug business?