The Association Between Cannabis Use and Schizophrenia: Causative or Curative? A Systematic Review

Area of Science:

• Neuroscience and Psychiatry
• Pharmacology
• Public Health

Background:

• Marijuana use is increasing globally, coinciding with its legalization in many regions.
• Understanding the impact of cannabis on mental health, particularly schizophrenia spectrum disorders, is crucial.
• Schizophrenia affects millions worldwide, and its relationship with cannabis requires thorough investigation.

Purpose of the Study:

• To systematically review the existing literature on the relationship between cannabis use and schizophrenia.
• To determine if cannabis causes, exacerbates, or potentially treats schizophrenia.
• To analyze the distinct effects of tetrahydrocannabinol (THC) and cannabidiol (CBD) on schizophrenia.

Main Methods:

• A systematic search was conducted across major databases (PubMed, Cochrane Library, Google Scholar) for relevant studies.
• Inclusion criteria focused on human studies, peer-reviewed English-language publications from the last five years.
• A quality assessment was performed on retrieved studies, with low-quality articles excluded, leaving 12 for final review.

Main Results:

• Ten studies supported a causative link between cannabis and schizophrenia.
• Eight studies indicated that marijuana exacerbates schizophrenia symptoms.
• Six studies suggested potential therapeutic effects of cannabidiol (CBD), contrasting with the adverse effects of THC.

Conclusions:

• Tetrahydrocannabinol (THC) is implicated as a primary factor in causing psychosis and schizophrenia in at-risk individuals.
• THC may worsen symptoms and prognosis for patients already diagnosed with schizophrenia.
• While CBD shows therapeutic promise, current data is limited, necessitating further research on its safety and efficacy.