Teen marijuana users had reduced brain blood flow, but it normalized after 4 weeks of abstinence
Heavy adolescent marijuana users showed reduced cerebral blood flow in multiple brain regions at baseline, but all differences disappeared after 4 weeks of confirmed abstinence.
Quick Facts
What This Study Found
Twenty-three heavy adolescent marijuana users (200+ lifetime use days) and 23 matched controls underwent brain perfusion scans at baseline and after 4 weeks of monitored abstinence (confirmed by urine testing). At baseline, users showed reduced blood flow in the left temporal cortex, insula, medial frontal gyrus, and supramarginal gyrus, with increased flow in the right precuneus.
After 4 weeks of abstinence, all between-group differences disappeared. No brain regions showed significant differences between former users and controls at follow-up.
This was the first study to examine cerebral blood flow in adolescent marijuana users, and its finding of full normalization after a month of abstinence suggested the neurovascular alterations were related to acute or subacute drug effects rather than permanent structural changes.
Key Numbers
23 users (200+ lifetime use days), 23 controls. Reduced blood flow in 4 cortical regions at baseline. Increased flow in right precuneus. All differences resolved after 4 weeks abstinence.
How They Did This
Prospective study with baseline and 4-week follow-up arterial spin labeling (ASL) MRI scans. 23 heavy adolescent marijuana users and 23 matched controls. Abstinence confirmed by sequential urine toxicology over 4 weeks.
Why This Research Matters
The reversibility of brain blood flow changes after just one month of abstinence is reassuring for adolescent cannabis users and their families. It suggested that at least some of the brain changes associated with heavy adolescent use are not permanent.
The Bigger Picture
This study helped distinguish between temporary drug effects and lasting brain changes in adolescent cannabis users. The finding that blood flow normalized does not rule out other types of lasting changes (structural, connectivity), but it is encouraging for the most common concern about teen brain damage.
What This Study Doesn't Tell Us
Four weeks may not be long enough for full normalization of all brain effects. Blood flow is only one measure of brain health. The study could not determine at what point during the 4 weeks normalization occurred. Relatively small sample.
Questions This Raises
- ?Do structural or connectivity changes also normalize with abstinence?
- ?How quickly does blood flow normalize, days or weeks?
- ?Would longer-term users take longer to normalize?
- ?Are there functional consequences of the reduced blood flow while using?
Trust & Context
- Key Stat:
- All brain blood flow differences resolved after 4 weeks of abstinence
- Evidence Grade:
- Prospective study with confirmed abstinence and pre/post imaging. Good design for a cannabis neuroimaging study but moderate sample size.
- Study Age:
- Published in 2012. Subsequent studies have continued to examine reversibility of cannabis-related brain changes in adolescents.
- Original Title:
- Altered cerebral blood flow and neurocognitive correlates in adolescent cannabis users.
- Published In:
- Psychopharmacology, 222(4), 675-84 (2012)
- Authors:
- Jacobus, Joanna(14), Goldenberg, Diane, Wierenga, Christina E, Tolentino, Neil J, Liu, Thomas T, Tapert, Susan F
- Database ID:
- RTHC-00575
Evidence Hierarchy
Enrolls participants and follows them forward in time.
What do these levels mean? →Frequently Asked Questions
Does teen marijuana use cause permanent brain damage?
This study found that brain blood flow differences in heavy teen users normalized after just 4 weeks of abstinence. While this does not rule out other types of lasting changes, it suggests at least some brain effects are reversible with stopping.
How long does it take for the brain to recover?
In this study, all blood flow differences had resolved by 4 weeks of abstinence. The study could not determine exactly when recovery occurred within that window. Other types of brain changes may take longer or shorter to normalize.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-00575APA
Jacobus, Joanna; Goldenberg, Diane; Wierenga, Christina E; Tolentino, Neil J; Liu, Thomas T; Tapert, Susan F. (2012). Altered cerebral blood flow and neurocognitive correlates in adolescent cannabis users.. Psychopharmacology, 222(4), 675-84. https://doi.org/10.1007/s00213-012-2674-4
MLA
Jacobus, Joanna, et al. "Altered cerebral blood flow and neurocognitive correlates in adolescent cannabis users.." Psychopharmacology, 2012. https://doi.org/10.1007/s00213-012-2674-4
RethinkTHC
RethinkTHC Research Database. "Altered cerebral blood flow and neurocognitive correlates in..." RTHC-00575. Retrieved from https://rethinkthc.com/research/jacobus-2012-altered-cerebral-blood-flow
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.