Recap: Cannabis & Marijuana Health Effects & Current State of Research

As of January 2017, more than half of all U.S. states have legalized medicinal marijuana, and eight states plus the District of Columbia have legalized cannabis for recreational use.

With these numbers growing along with the increasing varieties, forms and uses of cannabis and marijuana there’s also a lot more research and studying to be done to help the science and medicinal understandings.

A recent report released in January of this year by the National Academies of Sciences, Engineering and Medicine gives one of the most comprehensive looks - and, more importantly, the most up-to-date information - at what we know about cannabis. The report, entitled The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research (2017), mostly reveals that, while we still have a lot to learn, we do know a great deal about several specific health benefits of cannabis.

Researchers Investigate Potential Cannabis Health Benefits and Risks

Some of the highlights of the current 337-page cannabis and cannabinoids report included research of Therapeutic Effects. The list of these therapeutic areas studied included:
• Chronic Pain
• Cancer
• Chemotherapy-Induced Nausea and Vomiting
• Anorexia and Weight Loss
• Irritable Bowel Syndrome
• Epilepsy
• Spasticity Associated with Multiple Sclerosis or Spinal Cord Injury
• Tourette Syndrome
• Amyotrophic Lateral Sclerosis
• Huntington’s Disease
• Parkinson’s Disease
• Dystonia
• Dementia
• GlaucomaTraumatic Brain Injury/Intracranial Hemorrhage
• Addiction
• Anxiety
• Depression
• Sleep Disorders
• Posttraumatic Stress Disorder
• Schizophrenia and Other Psychosis
Additional information in the report showed effects in other health areas that included:
• Cancer
• Cardiometabolic Risk
• Respiratory Disease
• Immunity
• Injury and Death
• Prenatal, Perinatal, and Neonatal Exposure to Cannabis
• Psychosocial
• Mental Health
• Problem Cannabis Use
• Cannabis Use and the Abuse of Other Substances

The report included an overall recap in these areas as follows:
• For therapeutic effects: There is no or insufficient evidence to support the conclusion that cannabis or cannabinoids are an effective or ineffective treatment for the health endpoint of interest.
• For other health effects: There is no or insufficient evidence to support or refute a statistical association between cannabis or cannabinoid use and the health endpoint of interest.

Some Highlights & Good News for Marijuana in Medicine:


Can marijuana treat chronic pain? Researchers found evidence that adult patients who undergo treatment with marijuana “are more likely to experience a significant reduction in pain symptoms” such as inflammation associated with rheumatoid arthritis and irritable bowel syndrome.

Is cannabis effective for treating cancer? The study researched several types of cancer with a focus on glioma, a cancer that occurs in the brain and spinal cord. The study attempted to determine the anti-tumor effects of cannabinoids on these gliomas. The findings weren’t enough to support or refute the effects, so it was determined that more research needed to be done.

Does cannabis treat side-effects of chemotherapy? The study focused on researching vomiting and nausea symptoms caused by chemotherapy. The good news is that the report indicated strong evidence that cannabis is an effective way to treat chemotherapy-induced vomiting and nausea in cancer patients.

Do cannabinoids help control involuntary muscle spasms and stiffness? It was found that cannabis infused edibles, oral cannabinoids, did help to improve spasticity symptoms as reported by multiple sclerosis patients. 

Is THC helpful to those with Tourette Syndrome? The study cited that some case reports have suggested that cannabis, specifically THC capsules, can reduce tics and that the therapeutic effects of cannabis might be due to the anxiety-reducing properties of this type of marijuana use.

As the study continues, there are many other positive and negative effects related to cannabis use. Some of the negatives were noted in areas of Fetal Growth & Development, Memory & Attention issues, the increased risk of an accident while driving or operating a motor vehicle, but continues to qualify some substantial and moderate evidence for helping with things like certain Sleep outcomes and social anxiety disorders, and more. 

Many of the other areas of study offered sometimes moderate, but mostly limited or insufficient evidence to offer more conclusive information.

Conclusion: More Research is Needed


For decades, researchers have studied the effects of smoking cannabis, either as a therapy or for recreation. Science is taking positive steps to create and separate the research needed with findings and information to help us all uncover both the benefits and possible risks associated with marijuana.

Dr. Marie McCormick, professor of pediatrics at Harvard Medical School and chair of the NAS committee, is reported as saying: "For years, the landscape of marijuana use has been rapidly shifting as more and more states are legalizing cannabis for the treatment of medical conditions and recreational use. This growing acceptance, accessibility and use of cannabis and its derivatives have raised important public health concerns. Moreover, the lack of any aggregated knowledge of cannabis-related health effects has led to uncertainty about what, if any, are the harms or benefits from its use."

McCormick says of the study: "We conducted an in-depth and broad review of the most recent research to establish firmly what the science says and to highlight areas that still need further examination. As laws and policies continue to change, research must also."

Overall, the study and report shows what we’ve learned in recent years, what could be enhanced with further research and data, but it also demonstrates just how much more we need to learn.