
When you think of an “illicit drug” most people would plainly say “drugs are bad.” Not everyone thinks that about marijuana though. In fact, many people argue its great health benefits. Both proponents and opponents of cannabis have had a lot to say on the matter but which claims are true?
The Truth About the Effects of Marijuana
The National Academies of Sciences, Engineering and Medicine (NASEM) joined together to release a thorough report that answers the question “what are the effects of marijuana?”
The NASEM Report Stats
NASEM based its report on more than 10,700 abstracts of reports published since 1999, with an emphasis on papers published since 2011. According to Forbes, the committee was made up of experts in marijuana, addiction, oncology, public health, epidemiology, systematic review, cardiology, preclinical research, toxicology, immunology, pediatric and adolescent health, respiratory disease and neurodevelopment.
This committee of people was responsible for gathering the information and interpreting it for the new report. What the committee created, essentially, was a summary of the 10,700 abstracts of research which addresses a number of things, including how cannabis affects the health of those ingesting it.
NASEM experts grouped the health issues in 11 categories and labeled the information they gathered as having moderate, substantial, limited or no evidence. Below are some of the more hot-button categories and the effects of marijuana on each health category:

Effects of marijuana on cancer
The NASEM report did not find a large amount of evidence to support that marijuana has any effect on lung, head or neck cancers. Marijuana has not been labeled as a cause of cancer though (as many people have tried to claim previously).
Therapeutic effects of marijuana
The NASEM findings showed there is substantial evidence to claim that cannabis (marijuana) is an effective treatment of chronic pain. And, although cannabis doesn’t necessarily cure cancer, researchers found that marijuana is an effective treatment for nausea and vomiting that accompany chemotherapy.
However, there is limited evidence that proves that cannabis is an effective treatment for reducing symptoms of dementia, glaucoma or depression associated with chronic pain.
Marijuana as a gateway drug
You’ve heard people call marijuana a gateway drug in the past. There is only moderate evidence that cannabis use leads to a development of substance dependence or abuse in the future.
Developing an addiction to marijuana
Can you become addicted to marijuana? What causes the addiction? Well, there is no substantial evidence that many people become “addicted” to weed (not physically anyway). Men who smoke cigarettes, however, have more of a chance of developing problematic cannabis use in their lifetime.
Mental health effects of marijuana
Marijuana has been labeled as treatment for many mental health disorders. There has also been evidence that cannabis may help the development of other mental health issues. For example, substantial evidence was found that more frequent cannabis users have a higher chance of developing schizophrenia or psychoses. There is also a moderate association between marijuana smoking and the worsening of symptoms for people with a psychotic disorder. At the same time there has been moderate evidence that smoking marijuana can improve cognitive performance in people with a psychotic disorder.
It seems there is also moderate evidence that marijuana and thoughts of suicide (or committing suicide) can go hand-in-hand. Cannabis can also increase symptoms of PTSD for some people, according to the report.
Effects of marijuana on the brain
There is only moderate evidence that marijuana can impair your learning abilty, memory and attention (but only after immediately smoking it). There is only limited evidence of it affecting your brain health long-term or it affecting any other part of your life (i.e. low wages, unemployment, academic achievement).
Marijuana and respiratory disease
If you’re smoking marijuana, you may be wondering about its affects on your lungs. There is substantial evidence that there is an association between long-term marijuana smoking and an increase in chronic bronchitis. Also there has been moderate evidence that ceasing to smoke marijuana can have benefits on your respiratory health.
What Are The True Effects of Marijuana?

Essentially, the conclusion of the report is that more research is needed. It is startling to discover how much we still don’t know about the widely used drug. Only 12 of the conclusions in the report were found to be substantial and 25 are supported by moderate evidence. Additionally 27 claims about marijuana had limited or no evidence supporting them.
Conclusion
Basically what the report has done is given both proponents and opponents of legalization another point to argue. Many of the areas in which people have claimed marijuana can “cure” ailments aren’t necessarily true but it is a helpful treatment for many people. In the same light, many of the claims about marijuana being extremely bad for you aren’t true either.
So, if you’d like to base your next argument about marijuana on science and not ideological differences, the NASEM report is probably the best place to start but be prepared for those findings to change over the years as new research methods become available.
Photos: Katheirne Hitt, Cannabis Culture and Global Panorama