Cannabis, also known as marijuana, is one of the most widely used drugs in the world. Some people use it for medical reasons, while others use it recreationally.
As laws change in many countries, cannabis has become more available than ever before. Even though many people believe it is harmless, scientists have continued to study its effects on the brain because previous research has suggested that frequent cannabis use may increase the risk of psychosis in some people.
Psychosis is a serious mental health condition in which a person loses touch with reality. Someone with psychosis may hear or see things that are not really there, believe ideas that are clearly false, or struggle to think clearly.
Not everyone who uses cannabis develops psychosis, which has led researchers to ask an important question: why are some people more vulnerable than others?
A new study by researchers from the University of Pennsylvania Perelman School of Medicine and Children’s Hospital of Philadelphia offers an important clue.
The research, published in Molecular Psychiatry, focused on a brain chemical called glutamate. Glutamate is the most common chemical messenger that helps brain cells communicate with one another. Healthy glutamate activity is essential for learning, memory, thinking, and normal brain function.
The research team studied 79 volunteers with different levels of psychosis risk. Some participants had no mental illness, some were considered at high risk of psychosis, and others had already been diagnosed with psychosis.
Every participant completed detailed mental health assessments, answered questions about cannabis use, and provided urine samples to confirm recent cannabis exposure.
The researchers also used an advanced brain scanning method called 7-Tesla magnetic resonance spectroscopy. Unlike a standard MRI, this technique can measure the amount of certain chemicals inside the brain. The scientists focused on the anterior cingulate cortex, a brain region involved in emotions, decision-making, attention, and self-control.
The results showed that cannabis use and lower glutamate levels were each linked with more severe psychosis symptoms. Most importantly, cannabis users who had lower glutamate levels experienced the strongest positive psychosis symptoms, such as hallucinations and delusions.
The study also found signs that abnormal glutamate activity might contribute to depression and mania in some cannabis users. People already diagnosed with psychosis, especially those who used cannabis, tended to have lower glutamate levels than the other groups.
The findings do not prove that cannabis directly lowers glutamate or directly causes psychosis. Instead, they suggest that glutamate may be one of the biological links connecting cannabis use with mental illness.
Future studies following people over many years will be needed to answer whether cannabis changes glutamate or whether naturally low glutamate makes some people more vulnerable.
The researchers believe that future treatments aimed at restoring healthy glutamate activity could eventually reduce symptoms or lower the risk of psychosis in vulnerable people. This work may also help doctors identify which cannabis users face the greatest risk.
Overall, this is a carefully designed study using advanced brain imaging, but it involved only 79 participants, so larger studies are needed before firm conclusions can be reached.
The findings are important because they move beyond simply showing an association and begin to explain the possible biology behind it. Rather than suggesting cannabis is equally risky for everyone, the research indicates that individual brain chemistry may influence how people respond to cannabis. The study was published in Molecular Psychiatry.
If you care about health, please read studies that scientists find a core feature of depression and this metal in the brain strongly linked to depression.
For more health information, please see recent studies about drug for mental health that may harm the brain, and results showing this therapy more effective than ketamine in treating severe depression.
Source: University of Pennsylvania Perelman School of Medicine.
