Marijuana Use: The National Academy Report

Volunteers for Dennis Schuller campaigning in Northeast Minneapolis during the Open Streets Northeast event on a platform for "Legal Marijuana Now."

By Ajay K. Singh, MBBS, FRCP, MBA
Tuesday, January 24, 2017

The use of marijuana for medical treatment is legal in 28 states and the District of Columbia (DC). And recreational marijuana (or pot) has been legalized in eight of those states and DC.

Marijuana is derived from the dried leaves, flowers, stems, and seeds from the hemp plant, Cannabis sativa. Delta-9-tetrahydrocannabinol (Delta-9-THC) is the primary psychoactive ingredient in marijuana.

The January 12, 2017 publication of the report, “The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research” by the blue ribbon National Academies of Sciences, Engineering and Medicine in Washington, D.C. provides some important information on the risks and benefits of marijuana.

The report is available online and is very well worth a read. Highlights (excerpted) include:

Therapeutic Effects

  • In adults with chemotherapy-induced nausea and vomiting, oral cannabinoids are effective antiemetics.
  • In adults with chronic pain, patients who were treated with cannabis or cannabinoids are more likely to experience a clinically significant reduction in pain symptoms.
  • In adults with multiple sclerosis (MS)-related spasticity, short-term use of oral cannabinoids improves patient-reported spasticity symptoms.
  • For these conditions, the effects of cannabinoids are modest; for all other conditions evaluated, there is inadequate information to assess their effects.


  • The evidence suggests that smoking cannabis does not increase the risk for certain cancers (i.e., lung, head, and neck) in adults.
  • There is modest evidence that cannabis use is associated with one subtype of testicular cancer.
  • There is minimal evidence that parental cannabis use during pregnancy is associated with greater cancer risk in offspring.


  • Recent cannabis use impairs the performance in cognitive domains of learning, memory, and attention. Recent use may be defined as cannabis use within 24 hours of evaluation.
  • A limited number of studies suggest that there are impairments in cognitive domains of learning, memory, and attention in individuals who have stopped smoking cannabis.
  • Cannabis use during adolescence is related to impairments in subsequent academic achievement and education, employment and income, and social relationships and social roles.

Mental Health

  • Cannabis use is likely to increase the risk of developing schizophrenia and other psychoses; the higher the use the greater the risk.
  • In individuals with schizophrenia and other psychoses, a history of cannabis use may be linked to better performance on learning and memory tasks.
  • Cannabis use does not appear to increase the likelihood of developing depression, anxiety, and posttraumatic stress disorder.
  • For individuals diagnosed with bipolar disorders, near daily cannabis use may be linked to greater symptoms of bipolar disorder than non-users.
  • Heavy cannabis users are more likely to report thoughts of suicide than non-users.

The 16-member National Academy committee comes to the following conclusion, “There is conclusive or substantial evidence that cannabis or cannabinoids are effective:

  • For the treatment for chronic pain in adults (cannabis)
  • Antiemetic’s in the treatment of chemotherapy-induced nausea and vomiting (oral cannabinoids)
  • For improving patient-reported multiple sclerosis spasticity symptoms (oral cannabinoids)

[Develop your skills in clinical research for CME credit st HMS Global Academy.]

Ajay Singh, MBBS, FRCP

Dr. Ajay K. Singh is the Senior Associate Dean for Global and Continuing Education and Director, Master in Medical Sciences in Clinical Investigation (MMSCI) Program at Harvard Medical School. He is also Director, Continuing Medical Education, Department of Medicine and Renal Division at Brigham and Women’s Hospital in Boston.


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