The Long History and Emerging Science of Medical Cannabis in the United States | Research

The takeaway

Despite cannabis being used medicinally for millennia, US criminalization in 1937 (against AMA advice) suppressed research until the endocannabinoid system's discovery reinvigorated scientific interest.

Read this if you want the full historical arc of medical cannabis in America and the science behind its resurgence.

Cannabis was criminalized in 1937 against the American Medical Association's advice to Congress

What the researchers found

This review traced the arc of medical cannabis from ancient Chinese use (c. 2737 BCE) through its US history to the emerging science of the endocannabinoid system.

Cannabis was criminalized in the US in 1937, notably against the formal advice of the American Medical Association presented to Congress. This effectively ended medical use and research for decades.

The discovery of the endocannabinoid system transformed the field. Endocannabinoids were found to control pain, muscle tone, mood, appetite, and inflammation. Cannabis contains over 100 cannabinoids with the capacity for analgesia through neuromodulation, neuroprotection, and anti-inflammatory mechanisms.

Major institutions (NIH, Institute of Medicine, American College of Physicians) had issued statements supporting further research. The review focused on applications in chronic pain, muscle spasticity, cachexia, and other debilitating problems.

Why it matters

This review placed the modern medical cannabis movement in historical context, showing that the current resurgence is not a new phenomenon but a return to pre-prohibition norms, now supported by modern neuroscience.

The numbers in context

Cannabis use documented since c. 2737 BCE. Criminalized in US in 1937. Over 100 cannabinoids identified. NIH, IOM, and ACP issued support statements for research.

How the study worked

Historical and scientific narrative review covering the chronology of medical cannabis in the US, the endocannabinoid system, and current/emerging research on therapeutic applications.

What this study cannot tell us

Narrative review format without systematic methodology. Historical claims about ancient cannabis use are difficult to verify. The review presented a predominantly pro-medical-cannabis perspective.

How to read the evidence

This is a historical and scientific narrative review providing broad context rather than rigorous evidence assessment of specific therapeutic claims.

When this study was published

Published in 2009. The US medical cannabis landscape has changed dramatically since, with over 40 states now having some form of legal medical cannabis.

The bigger picture

The historical perspective in this review has been influential in policy discussions, highlighting that cannabis prohibition was a relatively recent historical anomaly in the context of millennia of medical use.

Questions still open

How has the criminalization era affected the quality and quantity of cannabis research? Can the regulatory framework evolve fast enough to keep pace with scientific understanding?

Common questions

Why was cannabis criminalized against medical advice?

The Marihuana Tax Act of 1937 was driven by political, racial, and economic factors rather than medical evidence. The AMA objected on record to Congress but was overridden. The specific motivations are still debated by historians.

How many cannabinoids are in cannabis?

Over 100 unique cannabinoids have been identified in cannabis. THC and CBD are the most studied, but others like CBG, CBC, THCV, and CBN also have pharmacological activity.

Read the original research

Medicinal use of cannabis in the United States: historical perspectives, current trends, and future directions.

Journal of opioid management, 5(3), 153-68

View on PubMed ↗

Citation

Aggarwal, Sunil K; Carter, Gregory T; Sullivan, Mark D; ZumBrunnen, Craig; Morrill, Richard; Mayer, Jonathan D. (2009). Medicinal use of cannabis in the United States: historical perspectives, current trends, and future directions.. Journal of opioid management, 5(3), 153-68.