THC has some potent effects against cancer, heart disease, pain, nausea, and insomnia. It can also help with seizures, insulin sensitivity and improve brain function in certain ways.
What is Tetrahydrocannabinol (THC)?
Tetrahydrocannabinol (THC), also known as delta9-tetrahydrocannabinol, is the primary component of cannabis responsible for its psychoactive properties. It is considered a secondary metabolite of the plant marijuana that serves as a defense mechanism to prevent consumption of the plant (R).
THC in the Cannabis plant needs to be heated in order to be efficiently utilized by the body (R).
Medical use of cannabis dates back as far as 16th century B.C. by the Egyptians, and subsequently by the Greeks and Romans. A cannabis extract containing THC metabolites was found inside a tomb in Israel on remains of a young woman who appeared to have died giving birth (R). The archeologists who discovered the tomb speculated that the cannabis was used to facilitate the birth process.
Current Uses of THC in Medicine
Although CBD may be a more popular constituent of cannabis for therapeutic purposes, synthetic forms of THC such as Dronabinol have been approved for the treatment of nausea, vomiting, and loss of appetite in chemotherapy and AIDS patients (R).
Nabiximols, a cannabis extract, is a spray that can ease the symptoms of other spastic symptoms of treatment-resistant multiple sclerosis (R).
Route of Administration and Pharmacokinetics of THC
There are many different routes of administration, with varying absorption and elimination rates, depending on the purpose of use (R).
- Smoking or absorption of THC via the lungs results in rapid and efficient absorption with 2 – 56% bioavailability of THC and its metabolites. Peak levels in the blood are detected after 12 minutes.
- Oral or ingestion of THC result in a lower, more gradual and blunted peak in serum concentration of THC. Serum levels peak at around 1.5 – 2 hours. Chocolate cookies with cannabis have ~6% bioavailability 1 – 5 hours post-ingestion. The absorbed cannabis is also subject to first-pass liver metabolism.
- Sublingual, rectal, and skin uses of THC are somewhat less effective than smoking and injecting, but more effective than ingesting THC because these methods all bypass the digestive system and first-pass liver metabolism. In addition, the THC metabolites stay longer in the system when consumed via these less effective routes. Because smoking may cause other side-effects from smoke exposure, these other routes of administration may be favorable where a prolonged result is desired.
THC is a highly fat-soluble substance, which means that it has a preference for lipid-rich tissues such as lungs, hearts, brain, and liver (R).
Brain levels of THC are almost always higher than blood levels, and there may be THC in the brain even when it is absent in the blood. Chronic use of THC can result in THC accumulation in fat tissues (R).
THC readily crosses the placenta in dogs and sheep (R).
The Good: Health Benefits of Tetrahydrocannabinol
1) THC Benefits Cardiovascular Diseases
Marijuana use is typically associated with other unhealthy behaviors such as a high-calorie diet, smoking, and other drug use (R). However, mechanistic studies found that THC itself (without those unhealthy lifestyle factors) have shown that THC may help reduce cardiovascular disease risk.
THC Hinders Progression of Atherosclerosis Plague
Patients developing atherosclerosis or hardening of arteries have increased levels of foam cells in the major arteries which lead to deposition of cholesterol and fatty plaque (R).
In rats, similar results were shown through supplementation of low levels THC to reduce atherosclerosis without psychoactive effects (R).
THC inhibits the 15-lipoxygenase enzyme, which is an enzyme that oxidizes low-density lipoprotein (R).
THC’s anti-inflammatory effects reduce platelet accumulation and promote immune function in the heart, which inhibits atherosclerosis (R).
2) THC May Inhibit Tumor Growth and Help Prevent Cancer
Glioblastoma multiforme is a deadly and hard to treat a form of brain cancer with limited treatment options and a low life expectancy. Direct injection of THC into the glioblastoma tumors inhibits tumor cell proliferation and increased the median life expectancy by about 24 weeks (R). A cellular study found that CBD enhances this effect of THC (R).
Treatment of breast cancer cells in mice showed that low doses THC (.5 mg/day) served significant anti-tumor properties. THC reduced growth, number, and overall blood vessel number in the breast tumors (R).
In a survey of people who are habitual THC users but not cigarette smokers, the use of THC did not increase the incidence of lung cancer, although negative outcomes from smoking THC were not ruled out (R).
The interplay between cannabinoid receptor and prostate cancer prognosis is complex. Some studies found that THC inhibits cell growth, while others found it enhances cell growth (R).
3) THC Stimulates Appetite and Can Help With Nausea
In patients suffering from HIV, cancer or other diseases that lead to decreased appetite and muscle wasting, THC and other cannabis substances has been studied as an effective treatment to stimulate appetite and mitigate cachexia (R).
4) THC Helps with Pain Management
Oral ingestion of THC in patients suffering from multiple sclerosis (MS) reduced symptoms. The maximum dosage of 25 mg of THC over the course of 15 weeks reduced pain and muscle stiffness. Also, perceived notions of healing in patients with MS increased after taking THC, improving the quality of life (R, R2, R3).
5) THC Can Help Insomnia and Increase Deep Sleep
Cannabis and THC administration appears to decrease the time it takes to fall asleep and increase stage 4 sleep, but decrease REM sleep (R).
6) THC Helps Prevent Seizures
In a rat model, THC completely abolishes epileptic seizures (R).
7) THC Increases Insulin Sensitivity
An epidemiological study found that current marijuana use is associated with 16% lower fasting insulin levels in comparison to past marijuana users and 26% in comparison to people who never used marijuana (R). This trend was also similar for other insulin resistance metrics, suggesting that THC increases insulin sensitivity.
8) THC Can Improve Your Brain in Some Ways
The Bad: Adverse Effects of THC
THC can cause schizophrenia-like symptoms, altered perception, increased anxiety, delayed recall time, impaired mental performance, and increased cortisol (R).
After ingesting a high dose of THC, increased levels of adrenaline were detected after 2 hours but then returned to normal after 4 hours (R).
THC may reversibly block synaptic neuroplasticity in the nucleus accumbens and hippocampus (R).
Highly potent cannabis may impair creativity and divergent thinking (R).
Repeated use of cannabis can result in intolerance due to a reduction in CB1 receptors (R).
Prior THC exposure can make nicotine more addictive in rats (R).
Technical: Actions of THC Receptors and Neurotransmitters
THC is a CB1 and CB2 partial agonist. THC binds to CB1 receptors on GABAergic and glutamatergic neurons, thus disrupting signaling systems to dopaminergic neurons (R, R2). In addition, THC allosterically modulates opioid receptors (R).
THC causes euphoric state through increasing of dopamine signaling, although the chronic use of THC can blunt the dopamine receptors (coded by DRD1 and DRD2 genes) (R). The effects of THC on the dopamine system appears to be dependent on dose and duration of use (R).