A neuroimaging review found that marijuana use, particularly when started during adolescence, is associated with alterations in brain structure and function that may underlie cognitive deficits observed in users.
Parents, educators, and anyone interested in how cannabis affects the developing brain.
Adolescent brains are particularly vulnerable due to ongoing myelination and synaptic pruning
What the researchers found
This review examined neuroimaging evidence on how marijuana affects brain structure and function, with a focus on developmental timing.
A wide range of research has documented neurocognitive deficits associated with marijuana use, particularly when use begins during childhood or adolescence. Neuroimaging studies have begun to reveal potential mechanisms, showing alterations in both brain structure (volume, white matter integrity) and brain function (activation patterns during cognitive tasks).
The review used a neurodevelopmental framework to contextualize these findings, noting that the adolescent brain is particularly vulnerable because key processes like myelination and synaptic pruning are still ongoing during this period.
Why it matters
Understanding the brain mechanisms behind cannabis-related cognitive deficits is important for both clinical practice and public health messaging. The neurodevelopmental framework highlights why adolescent exposure is of particular concern.
The numbers in context
The review noted marijuana is the third most popular recreational drug in America (behind tobacco and alcohol) with rising prevalence rates. Specific neuroimaging findings varied across studies.
How the study worked
This was a review chapter examining recent neuroimaging data (structural MRI, functional MRI, diffusion tensor imaging) on brain changes associated with marijuana use, organized within a neurodevelopmental framework.
What this study cannot tell us
Most neuroimaging studies are cross-sectional, meaning they cannot determine whether observed brain differences existed before cannabis use began. Differences in study populations, cannabis use patterns, and neuroimaging methods make direct comparisons difficult. The review noted the need for longitudinal studies that follow individuals from before cannabis initiation.
How to read the evidence
This is a review of neuroimaging studies providing moderate evidence, noting that most included studies are cross-sectional and cannot prove causation.
When this study was published
Published in 2016. Neuroimaging research on cannabis and brain development has continued to advance.
The bigger picture
The question of whether cannabis permanently alters brain development is one of the most important in cannabis research. This review provided a snapshot of the neuroimaging evidence suggesting structural and functional changes, though the question of reversibility remained largely unanswered.
Questions still open
- Are the brain changes associated with adolescent cannabis use reversible with abstinence? Do they translate to meaningful real-world functional impairments?
Common questions
Does marijuana damage the teenage brain?
Are the brain effects of marijuana permanent?
Read the original research
Effects of Marijuana Use on Brain Structure and Function: Neuroimaging Findings from a Neurodevelopmental Perspective.
International review of neurobiology, 129, 33-65
Citation
Brumback, T; Castro, N; Jacobus, J; Tapert, S. (2016). Effects of Marijuana Use on Brain Structure and Function: Neuroimaging Findings from a Neurodevelopmental Perspective.. International review of neurobiology, 129, 33-65. https://doi.org/10.1016/bs.irn.2016.06.004
Explore the wider topic
- How to Talk to Your Teenager About Weed (Without Losing Them)
- My Kid's Friends Smoke Weed: A Parent's Guide
- I Smoke Weed But Don't Want My Kids To: Navigating the Hypocrisy
- Quitting Weed as a Parent: Why It Is the Hardest and Most Important Quit
- Quitting Weed as a Teen or Young Adult
- My Kid Is Smoking Weed: A Parent's Guide