Does Cannabis Really Help PTSD? New Data Cast Doubt

New research challenges the assumption that long-term cannabis use improves symptoms or functioning in post-traumatic stress disorder (PTSD).

On the contrary, researchers found that abstaining from cannabis for 3 months was associated with significantly greater reductions in PTSD symptoms in adults with PTSD and comorbid cannabis use disorder (CUD).

The data suggest that continued cannabis use could limit recovery in some domains — underscoring the need to routinely assess cannabis use during PTSD treatment and to educate patients on the potential consequences of continued use, the researchers said.

The study, was published online February 18 in the Journal of Clinical Psychiatry.

Helpful or Harmful?

PTSD is a debilitating psychiatric condition marked by intrusive memories, avoidance, negative changes in mood and cognition, and hyperarousal. Many patients turn to cannabis to ease symptoms. In one recent study, roughly 28% of individuals with PTSD reported past-year cannabis use and 9% met criteria for CUD.

Although some studies have suggested PTSD symptom reduction with cannabis or cannabinoid-based treatments, others have identified potential risks, such as disrupted fear-extinction learning and worse clinical and treatment outcomes.

A recent systematic review found mixed evidence overall, with six studies suggesting benefits, five reporting worsening of symptoms, and three showing no significant impact of cannabis use in the setting of PTSD.

Led by Ahmed Hassan, MD, University of Toronto, Ontario, the researchers recruited adults aged 18-65 years with confirmed PTSD and CUD through the Centre for Addiction and Mental Health in Toronto and asked them to discontinue cannabis for 12 weeks.

Abstinence was defined as a urine 11-nor-9-carboxy-tetrahydrocannabinol level of 50 ng/mL or lower with no self-reported use, verified at multiple timepoints. Participants received escalating cash incentives for remaining abstinent at weeks 4, 8, and 12.

Eleven (52%) of the 21 participants who completed the 12-week protocol achieved biochemically verified abstinence, while 10 did not.

Those who achieved abstinence reported significantly greater reductions in total PTSD symptom severity and symptom count compared to those who did not.

Total severity scores on the Clinician-Administered PTSD Scale for DSM-5 dropped from 36.2 at baseline to 10.5 at week 12 among abstainers vs 34.6 to 21.8 among those who did not maintain abstinence (P = .001).

A similar pattern emerged for total symptom count, with abstinent participants dropping from 14.3 symptoms at baseline to 4.1 at week 12, compared to a decrease from 13.5 to 8.9 among non-abstainers.

Notably, the investigators observed that individuals who remained abstinent showed greater reductions in several core symptom clusters, including avoidance, negative alterations in mood, cognition, and hyperarousal domains that are often cited as targets for cannabis-based self-medication among individuals with PTSD.

“However, in this comorbid PTSD and CUD sample, sustained cannabis abstinence was associated with symptom improvement, thereby challenging assumptions about its clinical utility in this population,” they wrote.

Interestingly, they added that there were no differential effects on re-experiencing symptoms such as flashbacks, intrusive memories, and nightmares. Both abstinent and non-abstinent participants reported similar improvements in re-experiencing, suggesting that factors unrelated to cannabis use may have contributed to symptom change or insufficient power, the authors said.

The researchers called for larger randomized trials to “replicate and extend” these preliminary findings and to investigate mechanisms through which abstinence may relate to symptom changes in PTSD with CUD.

The study had no commercial funding. The authors had no relevant disclosures.

Note: This article originally appeared on Medscape.