Barriers to Research
Further research on the impact of cannabis is needed, however barriers to conducting this research exist. One such challenge is the classification of cannabis as Schedule I.
Smoking cannabis does not appear to increase the risk of cancers often associated with tobacco use, as per the study. Limited evidence was found regarding an increased risk of one sub-type of testicular cancer or that cannabis use by a parent during pregnancy is associated with greater risk of cancer in a child.
A recent survey showed that 22.2 million Americans have reported using cannabis in the past 30 days, with 90% saying it was for recreational use and the other 10% for medicinal purposes.
Some of the therapeutic effects of cannabis include treatment for chronic pain and chemotherapy-induced nausea. For MS patients, cannabinoid-based medications helped improve MS-related muscle spasms.
The committee looked at over 10,000 scientific abstracts to reach close to 100 conclusions.
National Academies of Sciences, Engineering, & Medicine
In order to further understand how cannabis impacts health, the National Academies of Sciences, Engineering, and Medicine conducted a study which included research published since 1999 on the health effects of cannabis and cannabis-derived products.
Evidence suggests that using cannabis before driving may increase the chance for motor vehicle accident. Also in states where cannabis is legal, the risk of accidental ingestion by a child is increased. More research is needed on how cannabis is linked to occupational injury or death.
Some evidence suggests that cannabis smoking may increase the risk of heart attack, however more evidence is needed to substantiate the claim; evidence on how cannabis impacts stroke and diabetes risk is also limited.
Smoking cannabis may increase the risk of respiratory disease such as chronic bronchitis, but quitting is likely to reduce the symptoms. It is unknown at this time whether cannabis use is linked to the development of COPD or asthma.
Regular exposure to cannabis smoke may have anti-inflammatory activity, based on limited evidence. Data is lacking on whether cannabis impacts the immune system or whether it produces adverse effects on the immune status of patients with HIV.
An increased risk for the development of psychiatric disorders such as schizophrenia and social anxiety disorder has been found with the use of cannabis; depression to a lesser extent. Individuals who are heavy cannabis users are more likely to report suicidal thoughts than non-users. For patients with bipolar disorder, near-daily cannabis use seemed to increase symptoms of the disorder. However, for patients with schizophrenia or other psychoses, a history of cannabis use has been associated with better performance on learning and memory tasks.
Initiation at a younger age and greater frequency of use were both associated with an increased likelihood of developing a problem with cannabis use. Moderate evidence exists that cannabis users are at increased risk for development of substance dependence and/or substance abuse disorder with substances such as tobacco, alcohol, and other illicit drugs.
Learning, memory and attention were all found to be impaired immediately after use, with limited evidence suggesting impairment in those who have stopped smoking cannabis. In addition, there is limited evidence to suggest that cannabis use impacts subsequent academic achievement and education, as well as social relationships. Cannabis use was also associated with increased unemployment rates and low income, though the evidence for this was limited.
Cannabis use during pregnancy has been associated with lower birth weight in the infant; other pregnancy outcomes have not been fully elucidated at this time.
Compiling data from over 10,000 scientific abstracts, the National Academies of Sciences, Engineering, and Medicine has published a report on the health effects of cannabis and cannabis-derived products. While over 100 conclusions were drawn from the data, the committee states that more research is needed to provide stronger evidence for some of these findings.
“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,” said Marie McCormick, chair of the committee; the Sumner and Esther Feldberg Professor of Maternal and Child Health, department of social and behavioral sciences, Harvard T.H. Chan School of Public Health; and professor of pediatrics, Harvard Medical School, Cambridge, Mass. “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. 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.”