One key memory function affected by PTSD is called mnemonic pattern separation. This process helps the brain distinguish between experiences that are similar but not identical. It primarily occurs in the hippocampus, a brain region crucial for learning and memory.

When mnemonic pattern separation doesn’t work well, which is common in PTSD, people may start to confuse safe situations with past danger. They might feel fear or want to avoid things that only remind them of the trauma. This mix-up between the past and the present can make it hard to move on from what happened.

Cannabis May Sharpen Memory In Severe PTSD Symptoms

In order to explore how cannabis affects this process, researchers assessed 111 participants suffering from a variety of PTSD symptoms. The group was split by cannabis use. There were 42 people who used it at least twice a week, while the other 69 used it rarely.

All participants completed the Mnemonic Similarity Task (MST), a widely used cognitive test designed to assess pattern separation. The test presents a series of images, some new, some repeated, and some similar but not identical, and asks individuals to classify them as “old,” “new,” or “similar.” A high score on the MST indicates strong pattern separation skills.

In those who used little or no cannabis, the study found a clear link between PTSD symptoms and memory performance. People with more severe PTSD symptoms were more likely to mistake similar images for ones they had seen before. These results suggest they had trouble telling closely related memories apart.

However, the results were quite different for regular cannabis users. In this group, people with more severe PTSD symptoms did better on the MST. They showed an improved ability to separate patterns.

These findings support the idea that cannabis use might help reduce some cognitive problems tied to PTSD, meaning that for those with stronger PTSD symptoms, cannabis could help them better tell apart safe and dangerous situations.

“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,” the study reads.

The study also found that among regular cannabis users with low PTSD symptoms, pattern separation performance was worse than in non-users. These people struggled more with memory confusion on the MST, suggesting that cannabis might hurt this cognitive function in people without severe PTSD.

“Regular users with high PTSD symptoms showed greater pattern separation, but reduced pattern separation with low PTSD symptoms,” the study reads.

Therefore, researchers suggest a possible ‘inverted U’ interaction between cannabis, PTSD severity, and memory performance. Cannabis seems to help with pattern separation in those at one end of the PTSD spectrum but hinders it in those at the other end.

While the study has some limitations, such as the fact that researchers mainly relied on self-reported cannabis use and only part of the group had urine tests to confirm THC use, the findings show “insights into the intricate relationship between PTSD, cannabis use, and mnemonic pattern separation ability,” as, with more people using medical cannabis for PTSD, it is crucial to understand how it impacts memory.