The bottom line is that the patient needs to be able to tolerate the side effects of cannabis on their ability to function in order to use it regularly. Some patients who find the effects of cannabis to be too debilitating on their daily function restrict its use to just evening, nighttime or days off from work.
- Anti-nauseant & appetite stimulant
- Analgesic (pain relief)
- Anxiolytic (highly variable)
- Harm reduction (reduce alcohol, NSAID, opioid use)
- Hypnotic (improved sleep)
- Immune system modulation
- Nervous system modulation
- Reduced intra ocular (eye) pressure
Medical conditions that have the best evidence based research to be treated with cannabis
Pain is the most common reason that cannabis is sought for medicinal use. Not everyone responds positively. Many patients report that they are still aware of their pain (neuropathic or nociceptive), but that they are not as bothered by it while using cannabis. Some patients experience complete pain relief from it, but that is not typical. Cannabis interacts with areas of the brain associated with higher function and seems to change the conscious perception of what pain is vs blocking neuro-chemical pathways to the brain like most drugs do (this has not been definitively proven yet). The lower portions of the brain that maintain our vital signs are spared from cannabinoid cell receptors, so that is why it is extremely difficult to overdose on it to the point of organ dysfunction or damage.
Regardless of the source of chronic pain, there is at least a moderate chance that cannabis will bring relief. The patient needs to balance any adverse effects from cannabis with their level of benefit from it, and to compare that balance with other options for analgesia (pain relief). Patients have reported clinical pain relief with conditions as varied as: cancer, osteoarthritis, rheumatoid arthritis, fibromyalgia, ankylosing spondylitis, gout, post-operative pain, spinal stenosis, headache, HIV, peripheral neuropathy, migraine, multiple sclerosis, sickle cell disease, thoracic outlet syndrome and many more.
Rat studies have indicated a synergistic effect of cannabis with morphine, so be wary of changes in effect, duration and side effects of opioid (Vicodin, oxycodone etc) medications while using cannabis. It is safe to expect opioids to have a stronger effect with concurrent cannabis use. So with continuous use of cannabis there is a substantial likelihood of being able to reduce the regular dose of opioids (enhanced analgesia). Many physicians require a reduction of opioids from their patients on continuous medical marijuana.
Smoked pain relief is comparable with gabapentin with HIV-related neuropathy.
Human trials have NOT shown cannabis to be highly effective for acute pain (new or sudden).
There is a theoretical concept that some migraine headaches are actually a result of a deficiency of endocannabinoids. This would explain the occasional patient with migraines who has found nothing better than cannabis for their headaches.
17 out of 20 studies of spasticity (multiple sclerosis or spinal cord injury related) have indicated a positive effect from cannabis.
Nausea can originate in multiple areas of the brain and is more complex to understand and to treat then emesis. Cannabinoid receptor activation, however, has proven effective in treating nausea and emesis. THC even proved to be more effective than prescription ondansetron in treating anticipatory nausea in rats. Conventional anti-emetics have not been highly effective in treating anticipatory or delayed nausea.
Recent research from the Hotchkiss Brain Institute at U of Calgary has established a CB 1 & 2 gut brain axis with humoral and neural components.
Cannabinoids have been demonstrated to inhibit emesis (vomiting) via receptor binding in the brainstem in animals.
Anorexia – a mixed bag:
Anorexia (no or little appetite) from cancer and AIDs has consistently been improved with administration of cannabis, dronabinol (Marinol) or nabilone (Cesamet). In addition to improving food intake, patients also experienced an overall improved sensory experience from the act of eating! Overall caloric intake, however, was only minimally improved.
Patients suffering from anorexia nervosa and bulimia nervosa have been found to have alterations in anandamide (an endocannabinoid) levels and elevated CB1 receptors. So until more detailed understanding of this phenomemon is established, a high level of caution is needed when using cannabis for appetite stimulation with this condition. Unless there is clinically significant improvement from cannabis without worsening of function, cannabis should be avoided here. It is theorized that anorexia nervosa might be the result of a disruption in the human endocannabinoid system itself.
Irritably Bowl Syndrome (IBS) & Inflammatory Bowel Disease (IBD) need to be evaluated on a case by case basis. The scientific evidence for these pathologies is growing but not substantial. Clinically, however, there is often a significant reduction of symptoms.
Known and established impairment from cannabis includes: effects on attention, memory, and perception.
Animal and neuro imaging studies have indicated a lessening of excitability in the amygdala region of the brain while consuming cannabis. The amygdala is associated with stress & anxiety, especially when it is hyperactive. It is possible that a deficit in the endocannabinoid (human) system can be a primary cause of anxiety. Mice bred to have low or non-existent endocannabinoid cell receptors have heightened anxiety and hyperactivity among other signs of high stress. More cannabis info on the neuro-chemistry of anxiety & stress
On the human side, the weight loss drug rimonabant was pulled from the market because it caused anxiety and depression in 1/3 of healthy people. This drug is an antagonist to cannabinoid cell receptors. So blocking the body’s ability to utilize cannabinoids is associated with causing anxiety. Several older human clinical studies have shown reduction in anxiety with synthetic THC (nabilone).
The paradoxical phenomenon of humans getting anxiety from cannabis is not understood from the biochemical perspective. It can and does occur though, even though most people experience a reduction in stress and anxiety from using cannabis. Smoking and Sativa strains of cannabis are most associated with anxiety. Here is a clinical article written by a psychiatrist that gives detailed info on selecting cannabis for anxiety.
Depression? Here is an article making some inroad for treatment with depression. I would suspect that an endocannabinoid deficiency would need to be part of the depression for cannabis to work as a treatment. Cannabis Depression Study
There is strong evidence for the benefits of cannabis in treating PTSD. The Fraser (2009) study found a 72% diminishment of PTSD related nightmares, after one week of taking 0.5mg of nabilone (synthetic THC) 1hr before sleep. Participants in the study also experienced improvement in sleep quality / duration and less flashbacks. Many animal studies also support the extinction of unwanted conditioned responses with cannabis.
This is a controversial area. There is correlation evidence of increased risk of inducing a psychotic event with cannabis, but the risk is relatively small. Additionally, many schizophrenics in the clinical setting swear up and down that cannabis controls their symptoms with the least adverse side effects.
The most at risk is the 15-18 year old with predisposing familial / environmental history. The adolescent developing brain can have its first psychotic event while using cannabis. So if there is any personal or family history of psychosis, cannabis should not be used until at least age 18. Other severe pathologies may override this concern, but must be considered on an individual case-by-case basis.
There is no evidence of increased risk of psychosis in the age 25-40 range.
On the brighter side, pure cannabidiol (CBD with no THC) has been found to reduce symptoms of schizophrenia in the recent Leweke (2012) study.
Treatment of cancer with cannabis is very controversial. There are many animal and lab studies indicating that various cannabinoids do in fact cause antitumor effects by various mechanisms, including induction of cell death, inhibition of cell growth, and inhibition of tumor angiogenesis invasion and metastasis, while not harming the normal tissues of the body. The medical community has yet to endorse cannabis as a viable cancer treatment. Many people in the lay community swear to its positive effect in treating some cancers. There are huge financial interests at stake. This web site is not a good source for cancer information. Here is a link to the National Cancer Institute’s patients page on cannabis . Here is the Health Professional Version
Here is an article exposing suppressed cannabis cancer research all the way back to 1974.
Here is a link to an informative Breast Cancer article
Other common medical indications for using Cannabis have included
Crohn’s disease, muscle spasms / cramping, epilepsy / seizures, glaucoma, cachexia / wasting, kidney failure, HIV – weight loss – mood – insomnia, Palliative Care (hospice), amyotrophic lateral sclerosis…
Here is a comprehensive synopsis of cannabis research ~ From NORML
Here is a link that grades cannabis medical evidence Mayo Clinic