Impaired mnemonic pattern separation associated with PTSD symptoms paradoxically improves with regular cannabis use
Jacob Ross, Bruna Cuccurazzu, Dylan Delmar, Christian Cortez, Giovanni Castillo, Dean T. Acheson, Dewleen G. Baker, Victoria B. Risbrough, Daniel M. Stout
npj Mental Health Research April 24, 2025 DOI: 10.1038/s44184-025-00126-w (opens in new tab) via OpenAlex
Summary
AI-generated from the abstractPosttraumatic stress disorder (PTSD) is linked to poor hippocampal function and disrupted pattern recognition. Cannabis use is common among people with PTSD, but its impact on these cognitive functions is unclear. In 111 participants with varying PTSD symptoms, regular and minimal cannabis users completed a mnemonic similarity task. High PTSD symptoms were associated with reduced pattern separation in minimal users. Regular users with high PTSD symptoms showed greater pattern separation, while those with low PTSD symptoms showed reduced pattern separation. The results suggest regular cannabis use may disrupt pattern separation and hippocampal-dependent processes, but may improve it in individuals with high PTSD symptoms. The cross-sectional design requires longitudinal follow-up to evaluate causal effects.
Study at a glance
| Characteristics | Cross-sectional study Longitudinal Peer reviewed |
|---|---|
| Sample size | 111 |
| Population | Individuals with a range of PTSD symptoms with and without regular cannabis use |
| Topics | Cannabis |
| Keywords | Mnemonic Cognition Separation statistics Posttraumatic stress |
| Citations | 1 |
| Key finding | Regular cannabis use was associated with greater pattern separation in individuals with high PTSD symptoms but reduced pattern separation in those with low PTSD symptoms. |
Abstract
Posttraumatic stress disorder (PTSD) is associated with poor hippocampal function and disrupted pattern recognition. Cannabis use is highly prevalent in individuals with PTSD, yet the impact on these cognitive functions is poorly understood. Participants (n = 111) with a range of PTSD symptoms with and without regular cannabis use completed the mnemonic similarity task. We hypothesized that regular use would be associated with alterations in pattern separation ability in individuals with PTSD symptoms. High PTSD symptoms were associated with reduced pattern separation performance in minimal users. Regular users with high PTSD symptoms showed greater pattern separation, but reduced pattern separation with low PTSD symptoms. These results suggest that regular cannabis use may disrupt pattern separation and similar hippocampal-dependent processes, while it may improve pattern separation in individuals with high PTSD symptoms. These cross-sectional results require longitudinal follow-up studies to evaluate the causal effects of regular cannabis use on cognitive function in PTSD.