The Health Effects of Cannabis: Informed Opinions

Walk into any bar or public place and collect opinions on cannabis and there will be a different opinion for each person surveyed. Some opinions will be well-informed from reputable sources, while others will simply be formed without any basis. To be sure, the investigation and conclusions based on the investigation are difficult given the long history of illegality. However, there is a current of opinion that cannabis is good and should be legalized. Many states in America and Australia have taken the path of legalizing cannabis. Other countries are following suit or considering options. So what is the position now? Is it good or not?

The National Academy of Sciences released a 487-page report this year (NAP Report) on the current state of the evidence for the topic. Many government grants supported the work of the committee, an eminent collection of 16 professors. They were endorsed by 15 academic reviewers and some 700 relevant publications were considered. Therefore, the report is considered state of the art in medical and recreational use. This article draws heavily on this resource.

The term cannabis is loosely used here to represent cannabis and marijuana, the latter coming from a different part of the plant. More than 100 chemical compounds are found in cannabis, each offering potentially different benefits or risks.

CLINICAL INDICATIONS

A person who is “high” from smoking cannabis may experience a state of euphoria where time is irrelevant, music and colors take on greater meaning, and the person may acquire the “bites”, wanting to eat sweet and fatty foods. This is often associated with impaired motor skills and perception. When high blood concentrations are reached, paranoid thoughts, hallucinations, and panic attacks can characterize your “trip.”

PURITY

In the vernacular, cannabis is often characterized as “good shit” and “bad shit”, alluding to the practice of widespread contamination. Contaminants can come from the quality of the soil (for example, pesticides and heavy metals) or be added later. Sometimes lead particles or small glass beads add to the weight sold.

THERAPEUTIC EFFECTS

Here is a random selection of therapeutic effects in the context of their state of evidence. Some of the effects will show up as beneficial, while others carry risks. Some effects are barely distinguishable from research placebos.

• Cannabis in the treatment of epilepsy is inconclusive due to insufficient evidence.

• Nausea and vomiting caused by chemotherapy can be improved with oral cannabis.

• A reduction in the severity of pain in chronic pain patients is a likely result of cannabis use.

• Spasticity in patients with multiple sclerosis (MS) was reported as improvement in symptoms.

• Increased appetite and decreased weight loss in HIV / ADS patients has been shown with limited evidence.

• Based on limited evidence, cannabis is ineffective in treating glaucoma.

• Based on limited evidence, cannabis is effective in treating Tourette syndrome.

• Cannabis has helped post-traumatic disorder in a single reported trial.

• Limited statistical evidence points to better outcomes for traumatic brain injury.

• There is insufficient evidence to say that cannabis can help Parkinson’s disease.

• Limited evidence dashed hopes that cannabis could help improve symptoms for those with dementia.

• Limited statistical evidence can be found to support an association between cannabis smoking and a heart attack.

• Based on limited evidence, cannabis is ineffective in treating depression

• The evidence for a reduced risk of metabolic problems (diabetes, etc.) is limited and statistical.

• Cannabis can help social anxiety disorders, although the evidence is limited. Asthma and cannabis use are not well supported by the evidence either for or against.

• Cannabis has helped post-traumatic disorder in a single reported trial.

• The conclusion that cannabis can help those with schizophrenia cannot be supported or refuted on the basis of the limited nature of the evidence.

• There is moderate evidence for better short-term sleep outcomes for people with sleep disorders.

• Pregnancy and cannabis smoking are correlated with reduced baby’s birth weight.

• The evidence for stroke caused by cannabis use is limited and statistical.

• Cannabis addiction and entry issues are complex, considering many variables that are beyond the scope of this article. These issues are discussed in depth in the NAP report.

CANCER

The NAP report highlights the following findings on the topic of cancer:

• Evidence suggests that smoking cannabis does not increase the risk of certain cancers (i.e. lung, head and neck) in adults.

• There is modest evidence that cannabis use is associated with a subtype of testicular cancer.

• There is minimal evidence that parental cannabis use during pregnancy is associated with an increased risk of cancer in the offspring.

RESPIRATORY DISEASE

The NAP report highlights the following findings on the topic of respiratory diseases:

• Regular cannabis smoking is associated with chronic coughing and phlegm production.

• Quitting cannabis is likely to reduce chronic coughing and phlegm production.

• It is not clear whether cannabis use is associated with a chronic obstructive pulmonary disorder, asthma, or impaired lung function.

IMMUNE SYSTEM

The NAP report highlights the following findings on the topic of the human immune system:

• There is a paucity of data on the effects of cannabis or cannabinoid-based therapies on the human immune system.

• There is insufficient data to draw general conclusions about the effects of cannabis smoke or cannabinoids on immune competence.

• There is limited evidence to suggest that regular exposure to cannabis smoke may have anti-inflammatory activity.

• There is insufficient evidence to support or refute a statistical association between cannabis or cannabinoid use and adverse effects on the immune status of people with HIV.

MORTALITY

The NAP report highlights the following findings on the issue of increased risk of death or injury:

• Using cannabis before driving increases the risk of being involved in a car accident.

• In states where cannabis use is legal, there is an increased risk of injuries from inadvertent cannabis overdose among children.

• It is unclear whether or not cannabis use is associated with all-cause mortality or occupational injuries.

BRAIN FUNCTION

The NAP report highlights the following findings on the topic of cognitive performance and mental health:

• Recent cannabis use performs strangely in the cognitive domains of learning, memory, and attention. Recent use can be defined as cannabis use within 24 hours of assessment.
• A limited number of studies suggest that there are deficits in the cognitive domains of learning, memory and attention in people who have stopped smoking cannabis.
• Cannabis use during adolescence is linked to deficiencies in academic performance and subsequent education, employment and income, and social relationships and social roles.
• Cannabis use is likely to increase the risk of developing schizophrenia and other psychoses; the greater the use, the greater the risk.
• In people with schizophrenia and other psychoses, a history of cannabis use may be related to better performance on learning and memory tasks.
• Cannabis use does not appear to increase the likelihood of developing depression, anxiety, and post-traumatic stress disorder.
• For people diagnosed with bipolar disorders, almost daily cannabis use may be associated with greater symptoms of bipolar disorder than for non-users.
• Regular cannabis users are more likely to report suicidal thoughts than non-users.
• Regular cannabis use is likely to increase the risk of developing social anxiety disorder.

It should be reasonably clear from the above that cannabis is not the magic bullet for all health problems that some well-intentioned but ill-advised cannabis advocates would have us believe. However, the product offers a lot of hope. Solid research can help clarify issues. The NAP report is a solid step in the right direction. Unfortunately, there are still many barriers to researching this amazing drug. Over time, the benefits and risks will be better understood. Confidence in the product will increase and many of the barriers, social and academic, will get in the way.