Study Explores Which Strains of Cannabis Improve Mental Health

Marijuana buds with marijuana joints on wooden tableMarijuana is illegal under federal law. Several states allow cannabis use within their borders. The U.S. Drug Enforcement Administration (DEA) says marijuana has no currently accepted medical use in treatment.

Nevertheless, several studies suggest marijuana may offer mental health benefits. A 2016 review found cannabis might treat some forms of addiction and improve symptoms of posttraumatic stress (PTSD). A 2015 study linked marijuana to improvements in chronic pain. Yet it remains unclear which chemicals in cannabis might be beneficial or what dosage is safe.

A new study published in the Journal of Affective Disorders explores the effectiveness of various marijuana strains for mental health symptoms. The research could eventually lead to evidence-based recommendations for the use of medical marijuana.

Medical Marijuana for Mental Health: Does it Work?

The study allowed medical cannabis users to track their symptoms of depression, anxiety, and stress through an app called Strainprint. Participants rated their symptoms on a scale of 1-10 before smoking cannabis. Then they input what type of cannabis they were using. Twenty minutes after smoking, participants reported the number of puffs they took and rated their symptoms again.

Within the study:

  • 561 people used the app to track their depression
  • 770 people used it to track symptoms of anxiety
  • 726 people used the app to track changes in their stress levels

Each participant made self-reports of mood and well-being. Researchers did not individually evaluate each participant.

By following changes in mood over time and analyzing data on the amount and type of cannabis users consumed, the team was able to draw several conclusions about the use of medical cannabis.

Cannabis in all forms significantly reduced short-term stress, anxiety, and depression. It did not, however, offer any long-term reductions in those conditions. Though stress and anxiety levels remained consistent, depression actually worsened with long-term cannabis use.

An Evidence-Based Approach to Medical Marijuana

The study also looked at the type and amount of cannabis consumed. Different strains of cannabis have different levels of cannabidiol (CBD) and tetrahydrocannabinol (THC). THC is the substance responsible for the “high.”

The study found cannabis high in CBD but low in THC offered improvements in depression with just one puff. Two puffs of any variety of cannabis offered improvements in anxiety. The most effective means to reduce stress was to take at least 10 puffs of a strain high in both CBD and THC.

Though preliminary, the study points toward options for the most effective use of cannabis in those who choose to use it for health reasons.


  1. Cuttler, C., Spradlin, A., & Mclaughlin, R. J. (2018). A naturalistic examination of the perceived effects of cannabis on negative affect. Journal of Affective Disorders. Retrieved from
  2. Drug fact sheet: Marijuana [PDF]. (n.d.). United States Drug Enforcement Administration. Retrieved from
  3. Scientific guidelines for using cannabis to treat stress, anxiety and depression. (2018, April 19). EurekAlert. Retrieved from

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