Decades of research show cannabis affects brain structure and cognition, raising questions for medical use | Research

The takeaway

A review found substantial evidence that recreational cannabis use impairs cognition, alters brain structure and function, and poses particular risks during adolescent development, while some cannabinoid compounds are paradoxically FDA-approved for medical use including in children.

Policymakers, pediatric prescribers, parents, and anyone navigating the tension between cannabis risks and medical benefits.

Medical use vs. recreational risk

What the researchers found

Decades of research link recreational cannabis use to cognitive impairment across multiple domains, structural and functional brain differences associated with early and heavy use, and heightened risks during adolescence when brain development is ongoing. Yet some cannabinoid formulations are FDA-approved, including for pediatric applications.

Why it matters

The tension between recreational cannabis risks and medical cannabinoid benefits is a central policy challenge. This review explicitly addresses this paradox, arguing that understanding brain effects should inform both recreational regulation and medical prescribing.

The numbers in context

Cannabis is the most widely used illicit substance worldwide. Legalization has substantially increased availability and use in the US. Brain development continues into early adulthood. Some cannabinoid formulations are FDA-approved for children.

How the study worked

Review consolidating findings on cannabis effects on brain structure, function, and cognition, with emphasis on implications for age limits and guidelines for both recreational and medical use.

What this study cannot tell us

Review-level evidence without meta-analytic pooling. Much of the underlying literature is cross-sectional and cannot establish causation. Recreational cannabis products differ substantially from pharmaceutical cannabinoids in composition and purity.

How to read the evidence

Rated moderate because the review synthesizes a large body of evidence, though the individual studies vary in quality and design.

When this study was published

Published in 2019.

The bigger picture

The same endocannabinoid system that makes cannabis potentially therapeutic is also what makes it potentially harmful to the developing brain. Navigating this tension requires nuanced policy that distinguishes between controlled pharmaceutical use and uncontrolled recreational exposure.

Questions still open

How should age limits for recreational cannabis be set based on brain development data? Do pharmaceutical cannabinoid products carry the same brain risks as recreational cannabis? What monitoring should accompany medical cannabinoid use in children?

Common questions

Does cannabis affect brain development?

Decades of research link early and heavy cannabis use to structural and functional brain differences and cognitive impairment, with adolescent use carrying particular risk due to ongoing brain development.

How can cannabis be both harmful and medically approved?

Pharmaceutical cannabinoids are controlled formulations used at specific doses for specific conditions. Recreational cannabis involves variable potency, uncontrolled dosing, and often targets developing brains. The risk-benefit calculus differs substantially.

Read the original research

Cannabis effects on brain structure, function, and cognition: considerations for medical uses of cannabis and its derivatives.

The American journal of drug and alcohol abuse, 45(6), 563-579

View on PubMed ↗Publisher’s paper ↗

Citation

Burggren, Alison C; Shirazi, Anaheed; Ginder, Nathaniel; London, Edythe D. (2019). Cannabis effects on brain structure, function, and cognition: considerations for medical uses of cannabis and its derivatives.. The American journal of drug and alcohol abuse, 45(6), 563-579. https://doi.org/10.1080/00952990.2019.1634086