I have been living in Portland
for almost two months now. For a very healthy/active city, they’re sure a lot
of smokers. As I type this post sitting at my kitchen table looking out to a
busy street, at least one in every four of the people walking by are smoking a
cigarette. Many of my patients are smokers, and a few are marijuana users. Yes,
recreational and medical marijuana is now legal in Oregon. In fact, medical and
recreational pot is now legal in Oregon, Washington, Alaska and Colorado, as
well as a handful of states in which it legalized for medical use only. I
realized that I don’t know the specifics of how marijuana affects the body and
it’s affects on healing. Surprisingly, there isn’t much information
specifically for physical/occupational therapists on how marijuana can affect
your treatment with your patient. So whether you are a user yourself or have
patients who use marijuana, continue reading for a comprehensive (but not
conclusive) review of how marijuana can affect different systems of the
body.
Note: This is not a pros/cons
article, or a stance paper to or for marijuana, it is simply FYI based on
scientific evidence.
Quick History of Marijuana
For thousands of years, marijuana was used for medicinal purposes,
specifically for its analgesic properties. The ancient Romans, Greeks and
Chinese used marijuana to treat various illnesses. In the 19th century, it was introduced to the UK
to be used as medical treatment. However, in the 1930s marijuana started to get
a bad rep. At that time, Harry Anslinger was the head of the Federal Bureau of
Narcotics and strongly opposed of marijuana use, grouping it with all narcotic
medications. He was unhappy with the “over prescription” of pain relieving
medication by physicians, and sought to decrease the availability of these
drugs. In 1937, the federal government criminalized medical marijuana use even
against the advice of the American Medical Society to do otherwise, and in
1942, it was officially removed. Within the last decade, medical marijuana has
be re-legalized in some states based on its treatment for glaucoma, nausea,
pain, anxiety, seizures, and spasticity. There are a zillion individuals which
stories about how marijuana helped to save their lives, but little research has
been performed on a large scale population. Scientists recently have focused on
conducting research on the potential benefits of marijuana, which has been
facing push back from the FDA with questions on how to regulate this
drug.
There are over 400 compounds found in cannabis, 60 of which are
considered cannabinoids. The following cannabinoids are found with the highest
concentration in marijuana:
- Tetrahydrocannabinol
(THC): Psychoactive,
therefore has effects on the brain since THC binds to CB1 receptors in the
brain, which is responsible for altering the mind. Because of the effects on
the brain, THC has been known make some users feel anxious or paranoid. Has a
sedative effect that may make some feel drowsy, but may also be helpful with
sleeplessness. THC also affects CB2 receptors, which are found in immune cells.
- Cannabidiol (CBD): Non-psychoactive, therefore it does
not give you that “high”. With less side effects, CBD is typically well
tolerated, even at high doses. CBD has been found to be an antiemetic (decrease
nausea/vomiting), an anticonvulsant, antipsychotic, anti-inflammatory,
anti-oxidant (combats neurodegenerative disorders), anti-tumoral/anti-cancer,
and an anti-depressant. It has no sedative effect. A form of CBD, Epidiolex,
got some attention in the news recently after it was found to decrease seizures
for children with rare forms of epilepsy.
Note: Marijuana is a Schedule I drug, making it difficult for
researchers to get grants to study the benefits. Therefore, there have been
very few studies on the affects of THC and CBD on humans; most studies have
been on animals.
Physical effects of marijuana on:
PULMONARY SYSTEM
Breathing: Frequent marijuana smokers can
have the same breathing issues as a tobacco smoker. Any kind of smoke
inhalation will irritate the lining of the lungs, which long term can lead to
chronic cough, phlegm production, wheezing, and bronchitis. Some studies have
found that smoke from marijuana contains many toxins, irritants, and
carcinogens, similarly to tobacco smoke. Typically, marijuana users inhale more
deeply and hold their breath longer than tobacco smokers, leading marijuana
smokers to more tar exposure per breath. (American Lung Association).
A 20-year study from UCSF and the University of Alabama at
Birmingham collected data from 5,000 U.S. tobacco and marijuana smokers. They
found that tobacco smokers in general smoked more frequently than pot smokers;
on average, tobacco users smoked 20 cigarettes/day vs. two to three times a
month for marijuana users. Therefore, you must keep that in mind when I tell
you the rest of the findings. Essentially with tobacco, the more you use, the
more you lose. The more tobacco that was smoked, the worse off one’s lung
function based off of measured air flow rate (speed in which a person can blow out
air), and lung volume (the amount of air a person is capable
of holding ie. 6 L for an adult male). This shouldn’t be too surprising.
However, the same linear relationship was not true for marijuana smokers. Air
flow rate increased with exposure to marijuana, up to a certain level.
(Remember… marijuana smokers in this study smoked two-three times per month).
CARDIOVASCULAR SYSTEM
Heart rate: Smoking pot can increase heart
rate up to two times for up to 3 hours after smoking. This has been found to
increase possibility of heart attack directly after inhalation. During an
exercise test, smokers reached their max heart rate quicker than non-smokers.
Blood pressure: The effects of marijuana on blood pressure are complex, depending on dose and administration. It often produces a temporary, moderate increase in blood pressure immediately after ingestion. However, heavy chronic doses may slightly depress blood pressure instead. One common reaction is to cause decreased blood pressure while standing and increased blood pressure while lying down, causing people to faint if they stand up too quickly (orthostatic hypotension). There is no evidence that marijuana use causes persistent hypertension and/or heart disease. Some users even claim that it helps them control hypertension by reducing stress. One thing THC does do is increase pulse rates for about an hour. This is not generally harmful, since exercise does the same thing, but it may cause problems to people with pre-existing heart disease. Chronic users may develop a tolerance to this and other cardiovascular reactions.
NERVOUS SYSTEM
Brain: Cannabis with a high percentage of THC (high - 10-14%, traditional = 2-4%) has been found to affect the corpus callosum, which is white matter of the brain that connects the right and left hemispheres. Therefore, communication between the two hemispheres may become less efficient. Researchers from this study did note that it can't be for certain if cannabis changes teh white matter, or if individuals with white matter changes are more likely to smoke. On the contrary, researchers are now finding that cannabis is a neuro-protectant, protecing brain cells from trauma, injury, or disease. Current studies are begin performed on the effects of marijuana for individuals with chronic traumatic encephalopathy (think concussions), PTSD, and Alzheimers.
Nerves: Marijuana offers potential neuromodulation and neuroprotection, which protects neurons from central nervous system damage including ischemia. This may also be way marijuana can be an effective treatment for chronic pain. Studies have found CBD to be a successful treatment for diabetic neuropathy, which is the leading cause of blindness in the U.S., by protecting the nerves of the eye. A study from the University of Glasgow in the UK found that cannabis oil sprayed helped treat debilitating neuropathic pain for patients with allodynia and multiple sclerosis.
Cognition: Studies have found that
infrequent users may have impaired cognition after inhalation, however complex
cognitive task performance was minimally affected in experienced users.
IMMUNE SYSTEM
Immunosuppressed: A study performed at the
University of South Carolina found that THC could suppress rodents’ immune
systems. It has been found to decrease the immune system for individuals who
are already immunosuppressed, such as those with an HIV infection. Researchers
believe this may be due to a mold called Aspergillus that grows on marijuana.
CBD has been found to modulate the immune system.
Autoimmune disorders: Individuals with autoimmune
disorders such as arthritis, type-1 diabetes, and multiple sclerosis whose
immune system is ramped up have been found to benefit from cannabis use.
“Normal” immune system: Studies on rodents have also
found that injected THC may suppress the BRCA2 gene (which is a protein that
normally suppresses tumor growth). The BRCA2 gene is associated with early
onset breast cancer, thus suppressing this gene could increase one’s risk of
breast cancer.
SKELETAL SYSTEM
Osteoporosis: A study at the University of Edinburgh in the UK
assessed the effects of cannabis on mice with age-related osteoporosis. They
found that marijuana helped to regulate peak bone mass through its effects on
decreasing osteoclast (type of cell that breaks down bone tissue) activity, and
regulated adipocyte (fat cells) and osteoblasts (bone formation).
Bone Healing: Ingesting marijuana deprives the cells of oxygen,
restricting the blood flow. Therefore, it can have a negative effect on healing
by slowing oxygen supply to the tissues. On the contrary, a study from Tel Aviv
University studied the effects of THC and CBD on rats with mid-femoral
fractures. The healing process sped up to an eight-week recovery with both the
THC and CBD treatment groups. Not only did CBD sped up recovery, it also
enhanced the maturation of the collagenous matrix which make the bone stronger,
suggesting it would be harder to break in the future.
Joints: Osteoarthritis (OA) is the most common type of
arthritis in which cartilage in joints wear away. There is currently no cure
for OA, however studies have found that cannabis helps to reduce swelling in
joints, and relieve pain for individuals with OA. Rheumatoid arthritis (RA) is
an autoimmune disease that affects the joints. Many individuals with RA are taking
multiple pain reducing and immunosuppressive medications with a long list of
negative side effects throughout their entire lives. THC has been found to be a
safe anti-inflammatory and pain relieving medication with minimal side effects.
MUSCULAR SYSTEM
The American Academy of Family Physicians (AAFP) found that long
term marijuana use reduces testosterone levels and growth hormone in men.
Lowered testosterone results in lowered muscle mass, as well as a feeling of
drowsiness. Decreased growth hormone results in slowing to body’s recovery
rate, causing muscle growth to delay. Decrease in these hormones may translate
into a decrease in effort during exercise, as well as a decrease in overload
during exercise that is necessary to improve cardiovascular performance and
muscle strength. However, other top athletes have reported that small amounts
of marijuana has helped them find new peaks in their training, allowing them to
find a controlled and meditative state. An Olympic skier stated that cannabis
causes him fearlessness, which allowed the pro to attack steeper slops with
more focus.
Smoke it? Eat it? Vap it?
Edibles may be a better solution to inhalation in order to
decrease some of the negative effects on the lungs that occur with smoking.
However, ingesting marijuana isn’t all it’s cracked up to be. This is mostly
due to the differences in how the drug is absorbed. When you consume marijuana,
it is absorbed by the stomach and liver where it is converted into an active
metabolite that is very effective in crossing the blood-brain barrier. This
results in a more intense high, however it usually takes between about an hour
to feel the effects with the effects lasting for several hours. Therefore,
people tend to overdo it. Smoked cannabis goes through a different metabolic
process in which THC travels directly to the brain, thus the effects can be
felt within 10 minutes and last approximately 30-60 minutes. There is also a
difference in the amount of cannabinoids that are delivered into the bloodstream
based on method of delivery. Edibles deliver 10-20% of THC into the bloodstream
versus inhaled cannabis, which is closer to 50-60%. Vaping or electronic
cigarettes have been found to be beneficial for decreasing second hand smoke as
well as the amount of carcinogens that are ingested. Even though there has been little
evidence of harm from their use, it is still premature to say for sure if it is
safe to use since no long-term studies have been performed. In addition, one of
the main components in e-cigarettes, propylene glycol (PG) is considered to be
safe for oral consumption; it is not known what the health risks are for
inhaling PG. Dr. Sanjay Gupta, a trained neurosurgeon and CNN’s chief medical
correspondent believes that if you are going to use marijuana, it is probably
best to use the vaporizing method since smoking creates a lot of unknown
byproducts, and ingesting leads to uneven absorption, while vaporizing seems to
activate the medicine without burning it.
Follow up questions you may want to ask your patients who use
cannabis:
How often?
What type?
What method?
BOTTOM LINE: Stay true to your scope of practice. But just like all medications, it is important to
know the effects in order to better understand/treat our patients.
For more information about where the medical community is today
with legalizing medical marijuana, check out Dr. Sanjay Gupta's 42 minute
documentary here: https://www.youtube.com/watch?v=QnVHxOPEbqc
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