Rat study finds high-THC cannabis smoke impairs working memory but not attention, while high-CBD smoke does not
In rats, acute exposure to high-THC cannabis smoke impaired working memory but left attention and impulsivity unaffected, while high-CBD cannabis smoke had no measurable cognitive effects.
Quick Facts
What This Study Found
High-THC cannabis smoke and THC injections impaired working memory on the TUNL task but had no effect on attention, impulsivity, or perseveration on the 5-CSRTT. High-CBD, low-THC smoke produced no cognitive impairments.
Key Numbers
THC injections produced significantly higher plasma THC than smoke exposure at 30 minutes post-treatment. High-CBD smoke significantly increased plasma CBD levels. Performance was worse at smaller spatial separations across all groups.
How They Did This
Adult male rats were acutely exposed to smoke from high-THC (Mohawk) or low-THC/high-CBD (Treasure Island) cannabis strains via inhalation chamber, or received THC injections (3.0 mg/kg i.p.). Cognitive performance was assessed using touchscreen-based TUNL (working memory) and 5-CSRTT (attention) tasks. Plasma cannabinoid levels were measured.
Why This Research Matters
This study directly compares different cannabis chemotypes (high-THC vs. high-CBD) on specific cognitive domains, helping clarify which cognitive functions are most vulnerable to THC.
The Bigger Picture
The finding that working memory is more sensitive to THC than attention or impulsivity suggests these cognitive domains have different thresholds for cannabinoid disruption, which may inform understanding of how different cannabis products affect daily functioning.
What This Study Doesn't Tell Us
Only male rats were tested. Acute exposure only, so chronic effects remain unknown. Smoke inhalation dosing is less precise than injection. The specific cannabis strains used may not represent all products available to humans.
Questions This Raises
- ?Would chronic exposure produce different patterns?
- ?Do female rats show the same selective vulnerability of working memory?
- ?Could CBD in the high-CBD strain be actively protecting against cognitive impairment?
Trust & Context
- Key Stat:
- Working memory impaired by THC; attention and impulsivity unaffected
- Evidence Grade:
- Well-controlled animal study with multiple comparisons, but findings may not directly translate to humans.
- Study Age:
- Published in 2022.
- Original Title:
- The effects of acute Cannabis smoke or Δ9-THC injections on the trial-unique, nonmatching-to-location and five-choice serial reaction time tasks in male Long-Evans rats.
- Published In:
- Neurobiology of learning and memory, 192, 107624 (2022)
- Authors:
- Barnard, Ilne L(4), Onofrychuk, Timothy J(4), Sandini, Thaísa M(2), McElroy, Dan L, Zagzoog, Ayat, Roebuck, Andrew J, Austin-Scott, Faith V, Laprairie, Robert B, Howland, John G
- Database ID:
- RTHC-03694
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
Which cognitive function was most affected by THC?
Working memory, tested using a touchscreen spatial task, was significantly impaired by both THC smoke and injection. Attention and impulsivity were not affected by any treatment.
Did the high-CBD cannabis strain cause any cognitive problems?
No. The low-THC, high-CBD strain (Treasure Island) did not impair working memory, attention, or any other measure, despite significantly increasing CBD levels in blood.
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Cite This Study
https://rethinkthc.com/research/RTHC-03694APA
Barnard, Ilne L; Onofrychuk, Timothy J; Sandini, Thaísa M; McElroy, Dan L; Zagzoog, Ayat; Roebuck, Andrew J; Austin-Scott, Faith V; Laprairie, Robert B; Howland, John G. (2022). The effects of acute Cannabis smoke or Δ9-THC injections on the trial-unique, nonmatching-to-location and five-choice serial reaction time tasks in male Long-Evans rats.. Neurobiology of learning and memory, 192, 107624. https://doi.org/10.1016/j.nlm.2022.107624
MLA
Barnard, Ilne L, et al. "The effects of acute Cannabis smoke or Δ9-THC injections on the trial-unique, nonmatching-to-location and five-choice serial reaction time tasks in male Long-Evans rats.." Neurobiology of learning and memory, 2022. https://doi.org/10.1016/j.nlm.2022.107624
RethinkTHC
RethinkTHC Research Database. "The effects of acute Cannabis smoke or Δ9-THC injections on ..." RTHC-03694. Retrieved from https://rethinkthc.com/research/barnard-2022-the-effects-of-acute
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.