CC’s ranking as the number one “Reefer
Madness” school in the 2011 Princeton Review may be what inspired the
Partnership for Civic Engagement to organize a series of discussions and
lectures informing the campus community about the science and politics of marijuana. On Tuesday, January 31st,
Psychology Department Chair and Associate Professor Lori Driscoll, presented a
lecture titled “Psychopharmacology of Cannabis: The Down Low on the High” to a
standing-room only crowd of CC students, professors, and Colorado Springs
community members in Tutt Science lecture hall.
A
systematic random sample conducted by Emily Chan's social psychology class
reported that of 77 CC students surveyed, 56 (72.7 percent) have smoked
marijuana at least once. For those who
do smoke marijuana, it is done with an average frequency of one to three times
per month. The number of students who
have an informed, scientific understanding of what the drug is doing to the
brain is likely to be much smaller.
Dr. Driscoll discussed two main scientific
components of the effects of cannabis, commonly known as marijuana, on the
brain and body: pharmacokinetics and pharmacodynamics. Pharmacokinetics is the effect the body has
on the drug. There are approximately 60 cannabinoids, or different
chemical compounds, in the plant. Of
these 60, the primary chemical agent causing the high during inhalation is
Tetrahydrocannabinol (THC). THC is lipid
soluble, meaning it can traverse the blood-brain barrier quickly, causing a
relatively rapid high. When inhaled, THC
enters the blood plasma via the lungs.
The THC-bound blood plasma’s primary target is the brain, but some will
also be transported to “depots” such as the liver. It is in the liver that most of the drug will
be metabolized and deactivated. Once it
has been metabolized, it will be excreted, primarily through the feces and
secondarily through urine. While THC
has a brain half-life of 20-30 hours, it is detectable in urine for up to 7
days after a single use and 30 days for a daily user.
Cannabinoids such as THC bind to receptors
on certain brain cells, or neurons, causing a signal to pass throughout the
brain. Variance in receptor-type
determines whether or not this signal will be excitatory or inhibitory. This phenomenon results in the mixed
experiences of marijuana users: suppression of laughter and increased
sensitivity are equally likely results. If
receptors are activated too frequently, down regulation will occur, diminishing
the number of receptors available for THC to bind to and leading to decreased
effects of the drug. Receptors that have
been down regulated are not permanently lost, but may take weeks to
recover. Tolerance to the cognitive
effects happens first, while tolerance to the motor effects is slower to
develop.
The
next concept Dr. Driscoll discussed was the pharmacodynamics of the drug, or
the effect of the drug on the body. THC
most severely affects the cerebellum and the substantia nigra, which are the parts
of the brain responsible for fine motor movement and initiation of
movement. This slowing of reflexes is
partially responsible for the dangers of driving a car while high. Interestingly, those under the influence of
marijuana are more likely than those under the influence of alcohol to remain
aware that driving under the influence is unsafe. Dr. Driscoll added that driving under the
influence of both alcohol and marijuana would be “very, very, very, very bad.”
In addition, a large number of cannabinoid
receptors exist in the hippocampus, which is the part of the brain that initiates
memory storage. This is responsible for
marijuana’s detrimental effects on memory.
Receptors in the basal ganglia are responsible for feelings of happiness
associated with the high, and the hypothalamus affects the user’s drive and
hunger. THC also affects the cerebral
cortex, the brainstem, and the amygdala, which can cause hallucinations, relief
from nausea and increased heart rate, and relief from traumatic memories,
respectively. The receptors in the
amygdala are also responsible for reduced anxiety in some cases, but increased
anxiety and panic in others. Although
specific characteristics of the high can be attributed to specific locations in
the brain, there are limitless compounding factors that make each user’s experience
unique. The extent to which one is
affected by the drug and the types of positive and negative effects experienced
depend not only on genetic factors, but also on the way one’s brain has shaped
over time. Emotional experiences, learning,
diet, liquid intake, and drug-use alter the brain physically, and any sort of
physical change to the brain can change the way a brain reacts to the presence
of any drug. In addition, since THC is
fat soluble, those with higher body fat percentages or slower metabolisms may
require more of the drug to achieve the same high. Dr. Driscoll confirmed that post-high
exercising may mobilize fat stores that contain THC, thereby restoring effects
of the drug long after the initial high has worn off. She also warned that it is possible to get
high “at a concert, just from standing downwind,” confirming that second-hand
smoke can have the same effects as direct inhalation.
Dr.
Driscoll stated that “We do not know of individuals who have died from overdose
on marijuana,” but nevertheless, “you can overdose.” The high desired by users may in fact relieve
pain, blunt traumatic memories, enhance sensory experiences, and cause most
individuals to relax. Yet the drug is
not without detrimental effects.
Marijuana use can lead to effects such as impaired attention and memory,
motor slowing and lack of coordination, and immune suppression; these effects
outlast the high, so students should not expect to function normally on Monday after
a weekend of marijuana use. In addition,
Dr. Driscoll noted that research has shown that marijuana use can interact with
genetics and increase the likelihood of becoming schizophrenic if one is
genetically predisposed.
Dr.
Driscoll ended her lecture with this take home message: in moderation,
marijuana use does not damage the brain, but it does temporarily change
it. There may be beneficial effects, but
the actions of the drug are not limited to those effects that produce the
high. Dr. Driscoll reminded her audience
that for those who consume habitually, “the way you feel off the drug will be
altered.”
‘There are so many ways that you can screw up your brain…this
is but one.”
This article was previously published in The Catalyst, a publication of the Colorado College in the 2011-2012 school year
This article was previously published in The Catalyst, a publication of the Colorado College in the 2011-2012 school year
