Cannabis use linked to short-term relief of PTSD symptoms in veterans

An ecological momentary assessment study of U.S. veterans found that days when participants reported a greater number of PTSD symptoms were followed by days when they experienced higher levels of negative affect, and vice versa. On days when veterans reported being high from cannabis for longer periods, they tended to report fewer PTSD symptoms and lower levels of negative affect. The paper was published in Psychiatry Research.

Post-traumatic stress disorder, or PTSD, is a mental health condition that can develop after a person experiences or witnesses a traumatic event such as combat, assault, accident, or disaster. It is characterized by intrusive symptoms like flashbacks, nightmares, or distressing memories that make the trauma feel as if it is happening again.

People with PTSD tend to avoid reminders of the event, including places, conversations, or activities linked to the trauma. They also experience negative changes in thoughts and mood, such as guilt, shame, emotional numbness, or feeling detached from others. Another core feature is hyperarousal, which can manifest as irritability, difficulty sleeping, an exaggerated startle response, or being constantly “on guard.”

Study author Jordan P. Davis and his colleagues wanted to explore the associations between daily variations in PTSD symptoms, cannabis use, and negative affect. They aimed to better understand how fluctuations in negative affect influence cannabis use when PTSD symptoms change at the daily level, and vice versa. Negative affect refers to a general experience of distressing emotions, including feelings like fear, shame, irritability, and nervousness. Unlike clinical diagnoses such as depression, negative affect is a broader indicator of unpleasant emotional states.

Study participants were 74 U.S. veterans with elevated PTSD symptoms who had recently been discharged from treatment and who also reported using cannabis in the past month.

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Participants completed a screening survey at the beginning of the study and were asked to provide daily data twice per day for three months. The data were collected using a mobile app called MAVERICK, built using IONIC Capacitor and developed by the study team. The app collects both passive data, such as information from wearable devices and health streams, and active data through questionnaires. On average, participants contributed data on 58 days.

Each day, participants completed short questionnaires in the morning and evening that asked about their cannabis use and the number of hours they were high, as well as their PTSD symptoms, using the Posttraumatic Stress Disorder Checklist for DSM-5 (4-item short form), and their levels of negative affect, measured using the Positive and Negative Affect Schedule – Short Form.

The results showed that days when participants experienced more PTSD symptoms tended to be followed by days when they experienced higher levels of negative affect. The reverse was also true: when participants experienced higher levels of negative affect on one day, they tended to report about 12 percent more PTSD symptoms on the following day, on average.

On days when participants reported more hours high from cannabis use, they also tended to report lower levels of negative affect and fewer PTSD symptoms, but these effects were limited to the same day. Finally, on days when participants reported more PTSD symptoms, they also tended to report higher levels of negative affect.

“Taken together, these findings underscore the importance of distinguishing acute, within-day co-variation from sustained therapeutic benefit, and highlight the need for further longitudinal and mechanistic studies to clarify whether cannabis use reflects a maladaptive coping strategy or merely coincident symptom alleviation,” the study authors concluded.

The study contributes to the scientific understanding of PTSD and its manifestations in everyday life. However, all results came from self-reports, leaving room for reporting bias to have influenced the findings. Additionally, the study was conducted on a relatively small and specific sample of veterans treated for PTSD, so results might not generalize to larger or more demographically diverse populations.

The paper, “Daily associations between posttraumatic stress disorder, cannabis use, and negative affect among veterans,” was authored by Jordan P. Davis, Shaddy K. Saba, Daniel Leightley, Eric R. Pedersen, John Prindle, Carl A. Castro, Bistra Dilkina, Emily Dworkin, Jonathan Cantor, and Angeles Sedano .