Adolescent THC exposure combined with a schizophrenia-linked gene mutation worsened emotional memory in adult mice
Mice carrying a schizophrenia-associated gene mutation showed greater emotional memory deficits when exposed to THC during adolescence than either factor alone.
Quick Facts
What This Study Found
Researchers studied mice carrying a mutation in the DISC1 gene (disrupted in schizophrenia 1) to test whether adolescent THC exposure interacts with genetic vulnerability to worsen adult brain function. Mice with the DN-DISC1 mutation already showed mild memory deficits, but chronic adolescent THC treatment significantly worsened fear-associated memory in adulthood.
At the molecular level, cannabinoid CB1 receptor expression was reduced in the prefrontal cortex, hippocampus, and amygdala by either the gene mutation or THC exposure independently. When combined, THC and the mutation produced a synergistic reduction in neural activity during fear memory retrieval in these brain regions.
The results demonstrated a gene-environment interaction: the genetic risk factor made the brain more vulnerable to adolescent cannabis exposure, producing deficits that persisted into adulthood.
Key Numbers
CB1 receptor expression was reduced in 3 key brain regions (prefrontal cortex, hippocampus, amygdala). Synergistic reduction in c-Fos expression was observed during cue-dependent fear memory retrieval in DN-DISC1 mice with adolescent THC exposure.
How They Did This
Controlled animal study using transgenic mice expressing dominant-negative mutant DISC1. Adolescent mice received chronic THC treatment, then underwent fear conditioning and memory testing in adulthood. Brain tissue was analyzed for CB1 receptor expression and c-Fos activation patterns.
Why This Research Matters
This study provides mechanistic evidence for the gene-environment interaction hypothesis in psychiatric illness. It suggests that adolescents carrying certain genetic variants may be disproportionately vulnerable to lasting cognitive effects from cannabis, which has implications for understanding differential risk.
The Bigger Picture
Not everyone who uses cannabis as a teenager develops lasting problems, and genetics may partly explain why. This study provides animal model evidence that specific genetic variants related to schizophrenia risk can amplify the effects of adolescent cannabis exposure on brain function.
What This Study Doesn't Tell Us
Animal model results do not directly translate to humans. The DISC1 mutation is one of many genetic factors linked to schizophrenia risk. THC was administered in isolation, without the other cannabinoids present in whole cannabis. Dosing patterns may not reflect human use.
Questions This Raises
- ?Could genetic screening identify adolescents at heightened risk from cannabis use?
- ?Would CBD co-administration protect against these gene-environment interaction effects?
- ?Do these fear memory deficits map onto specific psychiatric symptoms in humans?
Trust & Context
- Key Stat:
- Synergistic memory deficits in mice with both DISC1 mutation and adolescent THC
- Evidence Grade:
- Controlled animal study with transgenic mice. Findings are mechanistic and do not directly confirm human effects.
- Study Age:
- Published in 2015. The gene-environment interaction model continues to be investigated.
- Original Title:
- Adolescent cannabis exposure interacts with mutant DISC1 to produce impaired adult emotional memory.
- Published In:
- Neurobiology of disease, 82, 176-184 (2015)
- Authors:
- Ballinger, Michael D, Saito, Atsushi(2), Abazyan, Bagrat(2), Taniguchi, Yu, Huang, Ching-Hsun, Ito, Koki, Zhu, Xiaolei, Segal, Hadar, Jaaro-Peled, Hanna, Sawa, Akira, Mackie, Ken, Pletnikov, Mikhail V, Kamiya, Atsushi
- Database ID:
- RTHC-00909
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
Does this mean cannabis causes schizophrenia?
This study does not show that. It shows that in mice already carrying a genetic risk factor, adolescent THC exposure worsened specific memory deficits. The relationship between cannabis and psychosis in humans involves many additional factors.
What is the DISC1 gene?
DISC1 (Disrupted in Schizophrenia 1) is a gene that, when disrupted, has been associated with increased risk for schizophrenia and other psychiatric conditions. It plays a role in brain development and neural signaling.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-00909APA
Ballinger, Michael D; Saito, Atsushi; Abazyan, Bagrat; Taniguchi, Yu; Huang, Ching-Hsun; Ito, Koki; Zhu, Xiaolei; Segal, Hadar; Jaaro-Peled, Hanna; Sawa, Akira; Mackie, Ken; Pletnikov, Mikhail V; Kamiya, Atsushi. (2015). Adolescent cannabis exposure interacts with mutant DISC1 to produce impaired adult emotional memory.. Neurobiology of disease, 82, 176-184. https://doi.org/10.1016/j.nbd.2015.06.006
MLA
Ballinger, Michael D, et al. "Adolescent cannabis exposure interacts with mutant DISC1 to produce impaired adult emotional memory.." Neurobiology of disease, 2015. https://doi.org/10.1016/j.nbd.2015.06.006
RethinkTHC
RethinkTHC Research Database. "Adolescent cannabis exposure interacts with mutant DISC1 to ..." RTHC-00909. Retrieved from https://rethinkthc.com/research/ballinger-2015-adolescent-cannabis-exposure-interacts
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.