A systematic review has linked high-concentration THC cannabis products to negative mental health outcomes, particularly psychosis, schizophrenia, and cannabis use disorder.
A new systematic review has examined how cannabis products with high levels of delta-9-tetrahydrocannabinol (THC) are linked to mental health outcomes. The analysis revealed that products with elevated THC concentrations are tied to negative effects on mental health, especially when it comes to psychosis, schizophrenia, and cannabis use disorder (CUD).
The authors caution that existing research has important limitations. They stress the need for better-designed studies that can provide clearer and more reliable guidance for both healthcare providers and the general public. The review was published in Annals of Internal Medicine.
The investigation was led by researchers at the University of Colorado Anschutz Medical Campus, along with their collaborators. They evaluated 99 studies involving 221,097 participants conducted between 1977 and 2023. The selection criteria were deliberately wide-ranging, including any studies that assessed connections between high-concentration cannabis use and mental health outcomes, whether or not the original purpose of the research was to test therapeutic effects.
Defining High-Concentration THC
High-concentration cannabis products were defined as having THC concentration exceeding 5 mg THC or 10% THC per serving or products described as “high-potency concentrate,” “shatter,” or “dab.” The mental health outcomes of interest included anxiety, depression, psychosis, schizophrenia, CUD, and other substance use disorders. The researchers defined acute effects (within 12 hours), post-acute effects (after consistent use for 1 to 2 months), and long-term effects (after consistent use for > 1 year).
In studies not testing for therapeutic effects, high-concentration THC products were associated with psychosis, schizophrenia, and cannabis use disorder. No therapeutic studies found favorable effects on psychosis or schizophrenia.
Of non-therapeutic studies, 53% identified unfavorable associations with anxiety and 41% found unfavorable associations with depression. Among therapeutic studies, some suggested beneficial effects for anxiety (47%) and depression (48%), while others suggested unfavorable effects (24% for anxiety and 30% for depression).
The findings reinforce previous conclusions that higher THC concentrations increase the risk for adverse mental health outcomes; however, they fall short of providing the definitive evidence needed to provide clear advice to patients.
Reference: “High-Concentration Delta-9-Tetrahydrocannabinol Cannabis Products and Mental Health Outcomes” by Thanitsara Rittiphairoj, Louis Leslie, Jean-Pierre Oberste, Tsz Wing Yim, Gregory Tung, Lisa Bero, Paula Riggs, Kent Hutchison, Jonathan Samet and Tianjing Li, 25 August 2025, Annals of Internal Medicine.
DOI: 10.7326/ANNALS-24-03819
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8 Comments
As I read this article, I could not escape the impression that while strong marijuana seemed to cause mental disorders, the evidence was not conclusive that it did such damage.
As I sought to decide what the point of the article was, I cannot escape the feeling that it was designed to leave the casual reader with the impression that there was a problem, even though there was not definitive evidence of that.
Proper studys and documentation needs to be developed in order for people to actually know what the dangers are in no uncertain terms.
Young users likely conclude, since these test should provide definite answers. and they’re not able to prove it’s harmfulness. it must not be harmful.
As I read this article, I could not escape the impression that while strong marijuana seemed to cause mental disorders, the evidence was not conclusive that it did such damage.
It seems the point of it his article is to leave the casual reader with the impression that there was a problem, even though there was not definitive evidence of that.
Proper studies and documentation needs to be developed in order for people to actually know what the dangers are in no uncertain terms.
Young users might likely conclude, since these test should provide definite answers. and they’re not able to prove it’s harmfulness. it must not be harmful.
You can think what you want. Ive just submitted my wife to the psych ward for the 2nd time for taking these delta 9 gummies and weed pens. She wants to talk about getting her identity stolen and people reading her thoughts. She wants to talk about colors and the government, and dead bodies are what is stopping up our pipes.
Thank you for clarifying that to Green! I will keep your family in my prayers.
I cannot help but agree with your analysis of this article. Not to mention that it gives the doctors a reason to blow off someone who has a vomiting issue like gastroparesis and blame it on CHS when the cannabis was prescribed to combat the symptoms of stomach issues. I think the whole theory is b.s. From someone who unfortunately lands in the emergency room when a flare will not back off , if you have used cannabis to calm your symptoms it’s automatically CHS. This article is very premature before there’s any proof that cannabis is the cause of the vomiting.
BS !
Bull crap. Big Pharma/DEA propaganda.
After the millions of deaths caused by COVID19 vaccines would you still trust these so-called doctors?