242 Marijuana
Drawbacks.Although calling marijuana a hallucinogen stretches the defi-
nition of that type of drug, this book follows the governmental custom of
classifying marijuana in that category. Despite that official classification, re-
ports of hallucinations from marijuana are uncommon.
Physical effects can include reddened eyes, accelerated heartbeat, higher
body temperature, lowertestosteronelevel, and arousal of senses. In the 1970s
reports began appearing from laboratory and animal experiments indicating
that marijuana’s active ingredient THC harms immune system functions,
meaning infections may become more likely. Those experiments frequently
involved conditions that are not duplicated in the human body, however, and
by the 1990s fears about damage to the human immune system had quieted.
Marijuana is sometimes described as making people less interested in ac-
complishing tasks in life. Someone jokingly suggested that the substance in-
stead creates insatiable ambition to hold elective office. In reality, marijuana
does not make people unambitious. Such persons may be attracted to heavy
marijuana use, but probably they were unambitious before using the sub-
stance. One research study found that marijuana users who lack ambition tend
to be depressed and concluded that depression (not marijuana) was the un-
derlying cause for these persons’ diminished motivation. Case studies indicate
that marijuana can worsen psychoses, neuroses, and phobias.
In one study a battery of thinking tests given to groups of marijuana users
and nonusers found no difference in performance; in another study daily users
did worse than occasional users. Long-term memory (the ability to recall many
long-known things, such as remembering the year Columbus sailed to Amer-
ica) has been unaffected in experiments. Short-term memory performance
(brief ability to recall a few newly known things, such as a list of random
words) can decline during intoxication but afterward returns to normal. Some
researchers have found marijuana to have no influence on muscular coordi-
nation, sensory perception, mental ability, or learning; other researchers have
found that marijuana impedes muscular coordination and mental abilities.
Driving skill tests have shown similar variation; some studies find that mar-
ijuana harms such skill, and some do not. Some research shows marijuana
having no effect on users’ performance the next day; some research shows
impairment 24 hours after use. Such differing results may relate to intoxication
levels, to volunteers’ experience with handling the substance, and to how long
persons have been using it (some researchers believe that long-term use pro-
duces long-term effects extending beyond the time of acute intoxication).
The most obvious unwanted physical effects of marijuana are caused or
promoted by inhaling smoke, afflictions caused by the manner of dosing
rather than by the substance itself. In an animal experiment primates that
inhaled marijuana smoke were compared to those in a smoke-free group; the
marijuana group developed lung damage that could have led to bronchitis or
emphysema, had the smoking continued long enough. Among humans fre-
quent marijuana smoking is known to produce coughing, wheezing, and spu-
tum. Marijuana smoking reduces lung function in ways suggesting that
chronic obstructive pulmonary disease (COPD) might develop if a person
smokes four or five marijuana cigarettes daily for 30 years (with a lesser
amount needed if a person also smokes tobacco). Certain kinds of lung dam-