How THC Disrupts Spatial Memory by Silencing GABA Neurons in the Prefrontal Cortex

Animal study in male C57BL/6J mice. Intra-PFC injection of CB1 agonist ACPA via implanted cannula. Cognitive tests: novel object recognition test and object location test, with drug administered before acquisition, consolidation, or retrieval phases separately. In vivo microdialysis measured extracellular GABA levels. Chemogenetic activation of GABAergic neurons via AAV-GAD-hM3Dq and deschloroclozapine.

Memory impairment is one of the most consistent cognitive effects of cannabis, but understanding exactly which type of memory is affected and why is crucial for developing strategies to mitigate it. This study shows the effect is on learning new spatial information—not on recalling what you already know—and identifies a specific molecular pathway (CB1 → GABA reduction) that could potentially be targeted.

This provides the molecular mechanism for the memory impairment documented at the behavioral level in RTHC-00155 (cannabis + alcohol on verbal memory) and RTHC-00187 (THC impairing verbal recognition). The specificity to spatial memory acquisition—not retrieval or consolidation—helps explain real-world observations: cannabis users often struggle to form new memories while intoxicated but can recall previously learned information. The GABA connection also links to RTHC-00217's review of how cannabinoids affect GABAergic neurodevelopment.

Mouse study—prefrontal cortex organization differs between mice and humans. Used a synthetic CB1 agonist (ACPA), not THC. Direct injection into PFC doesn't model how inhaled or ingested THC distributes across the brain. Only male mice used. The memory tests are simplified versions of human spatial and recognition memory.