The Health Effects of Cannabis and Cannabinoids :The Current State of Evidence and Recommendations for Research

The Health Effects of Cannabis and Cannabinoids :The Current State of Evidence and Recommendations for Research

In one of the most comprehensive studies of recent research on the health effects of recreational and therapeutic cannabis use, a new report from the National Academies of Sciences, Engineering, and Medicine "The Health Effects of Cannabis and Cannabinoids"offers a rigorous review of relevant scientific research published since 1999 provides. This report provides a research agenda—outlining gaps in current knowledge and opportunities for providing additional insight into these issues—that summarizes and prioritizes pressing research needs

Significant changes have taken place in the policy landscape surrounding cannabis legalization, production, and use. During the past 20 years, 25 states and the District of Columbia have legalized cannabis and/or cannabidiol for medical conditions or retail sales at the state level and 4 states have legalized both the medical and recreational use of cannabis..

As of last fall, 57% of adults in the US said they thought marijuana should be legal, with only 37% taking the opposing view — which is essentially a reversal of the opinions held a decade ago. And after November's elections, 20% of Americans live in a state that has voted to legalize recreational use. Far more live in states with some access to medical marijuana.

These landmark changes in policy have impacted cannabis use patterns and perceived levels of risk. However, despite this changing landscape, evidence regarding the short- and long-term health effects of cannabis use remains elusive.

Shifting public sentiment, conflicting and impeded scientific research, and legislative battles have fueled the debate about what, if any, harms or benefits can be attributed to the use of cannabis or its derivatives, and this lack of aggregated knowledge has broad public health implications.

A new report released on 12 January by the National Academies of Sciences, Engineering, and Medicine gives one of the most comprehensive looks — and certainly the most up-to-date — at exactly what we know about the science of cannabis. The committee behind the report, representing top universities around the country, considered more than 10,000 studies for its analysis, from which it was able to draw nearly 100 conclusions.

The report's findings showed that cannabis and cannabinoids successfully eased chronic pain, improved symptoms of multiple sclerosis, and reduced nausea and vomiting in people undergoing chemotherapy.

But the evidence also suggested that cannabis use "is likely to" increase the risk of developing schizophrenia, other psychoses, and social anxiety disorders. For those already diagnosed with schizophrenia and other psychoses, however, having a history of cannabis use appeared to improve performance on learning and memory tasks.

According to the report, people who reported chronic marijuana use were more likely to have suicidal thoughts. Of those who were bipolar, almost daily cannabis use led to increased symptoms of bipolar disorder compared to non-users.

Though the research committee found "limited evidence" showing that cannabis use is a "gateway drug," they did present moderate evidence linking cannabis use and the development of substance use disorder for alcohol, tobacco, and other drugs.

The report also found some evidence that smoking marijuana "may trigger a heart attack," but noted that more research is needed to determine the relationship between cannabis and heart health.

A regular habit of smoking cannabis seemed to increase the prevalence of bronchitis, chronic cough, and phlegm. But the research also suggested that smoking pot does not increase the risk for lung, head, or neck cancers which are related to tobacco use. 

Learning, memory, and attention are impaired after immediate use of marijuana, said the report, and using before driving seemed to increase the risk of car accidents.

Limited evidence suggested that cannabis use was related to problems with academic achievement or social relationships. Smoking cannabis during pregnancy was linked to low birth weight, but evidence was weak for any other pregnancy complications. 

The report’s most significant conclusion seems to be that many more studies into the effects of using cannabis and its derivates are needed to truly understand its effect on one's health.

Researcher McCormick said that the growing accessibility and use of cannabis and its derivatives “have raised important public health concerns.”

"As a scientist, I think the goal is always to try very hard to get to the findings and to be able to disseminate those findings so that we can make good decisions grounded in science. Having good research is essential so that we know "how best we can use it, what are the safest ways, and what are the real risks. In studying cannabis, "we're not really after the good or the bad — we're after the truth,"" Staci Gruber, an associate professor of psychiatry at Harvard Medical School and director of the Marijuana Investigations for Neuroscientific Discovery program at McLean Hospital, told Business Insider in an interview last week, several days before we saw the report.