Nicotine may mask cognitive deficits from cannabis use in young people
A systematic review of 12 studies found evidence that nicotine co-use may conceal cannabis-related cognitive impairments in adolescents and young adults, while neuroimaging research on co-use remains scarce.
Quick Facts
What This Study Found
Cannabis and nicotine showed independent negative cognitive effects, but when used together, nicotine appeared to mask some cannabis-related cognitive deficits. Preliminary neuroimaging evidence pointed to hippocampal volume differences in co-users. No structural neuroimaging studies examined cannabis-nicotine co-use in adolescent-only populations.
Key Numbers
1,107 articles screened, 12 met inclusion criteria. Age range: 13-35 years. Preliminary evidence for hippocampal volume differences in co-users. No adolescent-only structural neuroimaging studies found.
How They Did This
Systematic review searching peer-reviewed articles for studies examining cannabis and nicotine/tobacco co-use in ages 13-35 (or nonadult animal subjects). From 1,107 initial articles, 12 met inclusion criteria requiring joint consideration of both substances and neurocognitive or neuroimaging outcomes.
Why This Research Matters
Cannabis and nicotine are frequently co-used, especially among young people. If nicotine masks cannabis-related cognitive problems, studies that do not account for co-use could systematically underestimate cannabis effects on the developing brain.
The Bigger Picture
The masking effect has practical implications. If nicotine compensates for some cannabis-related cognitive deficits, young people who use both substances may not notice cognitive problems until they quit nicotine. This also means existing research that does not separate co-users may have underestimated cannabis harms.
What This Study Doesn't Tell Us
Only 12 studies met criteria, limiting conclusions. Most studies were cross-sectional. No longitudinal studies specifically designed to examine co-use effects on brain development. Cannot determine mechanisms of the masking effect.
Questions This Raises
- ?What is the neurobiological mechanism behind nicotine masking cannabis cognitive effects?
- ?Does the masking persist long-term or only acutely?
- ?Would vaping nicotine produce the same masking effect as combustible tobacco?
Trust & Context
- Key Stat:
- Only 12 studies out of 1,107 examined co-use effects on the brain
- Evidence Grade:
- Systematic review with rigorous methods, but limited by the small number of qualifying studies and their mostly cross-sectional designs.
- Study Age:
- 2021 systematic review of available literature.
- Original Title:
- The Influence of Cannabis and Nicotine Co-use on Neuromaturation: A Systematic Review of Adolescent and Young Adult Studies.
- Published In:
- Biological psychiatry, 89(2), 162-171 (2021)
- Authors:
- Hernandez Mejia, Margie(2), Wade, Natasha E(18), Baca, Rachel(4), Diaz, Vanessa G, Jacobus, Joanna
- Database ID:
- RTHC-03198
Evidence Hierarchy
Analyzes all available research on a topic using a structured method.
What do these levels mean? →Frequently Asked Questions
Does nicotine protect the brain from cannabis effects?
Not exactly. The evidence suggests nicotine may mask or compensate for some cannabis-related cognitive deficits rather than preventing underlying brain changes. The hippocampal volume differences in co-users suggest structural effects still occur.
Why is this finding important for research?
Many cannabis studies do not adequately control for nicotine co-use. If nicotine masks cognitive effects, these studies may underestimate the true cognitive impact of cannabis on young brains.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-03198APA
Hernandez Mejia, Margie; Wade, Natasha E; Baca, Rachel; Diaz, Vanessa G; Jacobus, Joanna. (2021). The Influence of Cannabis and Nicotine Co-use on Neuromaturation: A Systematic Review of Adolescent and Young Adult Studies.. Biological psychiatry, 89(2), 162-171. https://doi.org/10.1016/j.biopsych.2020.09.021
MLA
Hernandez Mejia, Margie, et al. "The Influence of Cannabis and Nicotine Co-use on Neuromaturation: A Systematic Review of Adolescent and Young Adult Studies.." Biological psychiatry, 2021. https://doi.org/10.1016/j.biopsych.2020.09.021
RethinkTHC
RethinkTHC Research Database. "The Influence of Cannabis and Nicotine Co-use on Neuromatura..." RTHC-03198. Retrieved from https://rethinkthc.com/research/hernandez-2021-the-influence-of-cannabis
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.