According to a major study conducted in Denmark, chronic cannabis use significantly raises the risk of mental health problems and personality disorders, including major depression and bipolar disorder. The study analyzed medical records of over 6.6 million people born between 1995 and 2021, all of whom were at least 16 years old and from Denmark, where recreational cannabis use is illegal. However, it can still be accessed via the black market. The participants’ medical files were checked for cannabis use disorder (CUD), which is defined as being unable to stop using the drug even if it was causing damage to their health and social lives. Histories for major depression, with and without psychotic features, and bipolar disorder, with and without psychotic features, were also examined. The researchers found that chronically smoking cannabis raises the risk of psychotic bipolar disorder by 4.1 times, and any type of depression by 1.8 times. The findings align with previous research showing significant links between cannabis use and depression, but not bipolar disorder.
The study found that those who were addicted to marijuana were up to four times more likely to be diagnosed with major depression or bipolar disorder. Depression cases have been rising in recent decades, linked to growing and aging populations. However, the researchers warn that depression could become more common as marijuana becomes increasingly legal. It can be used recreationally in 22 US states.
The researchers noted that “a coherent model for how cannabis may influence the development of affective disorders is lacking.” They also highlighted that evidence that stopping cannabis use can reduce the risk of being diagnosed with a mental disorder is also lacking. The researchers emphasized the need for “improved knowledge on the dose-dependent effects of cannabis use on the brain, cognition, and behavior” and their findings have implications regarding cannabis legalization.
The study shows that cannabis use disorder is associated with a higher risk of any kind of bipolar disorder in men, with men three times more likely to suffer the condition compared to 2.5 times in women. This was the same for nonpsychotic bipolar disorder, with male chronic cannabis users three times more likely and female users 2.6 times to be diagnosed.
Cannabis use disorder was found to be primarily psychotogenic, meaning that it causes a psychotic reaction which could include delusions, delirium, and hallucinations. The main psychoactive element of cannabis, tetrahydrocannabinol (THC), acts on cannabinoid receptors and is thought to increase the risk of psychosis by disrupting normal brain functioning.
Several studies have found links between cannabis and schizophrenia in the past, though the exact cause is not clear. Marijuana can cause psychosis, impairing the way you think, make decisions, handle emotions, and interact with reality. It can also interfere with brain development in young people. But it may be that people who are schizophrenic simply use cannabis to ease their symptoms.
In conclusion, the study shows that chronic cannabis use is associated with an increased risk of major depression and bipolar disorder. The findings have implications for cannabis legalization and emphasize the need for improved knowledge on the dose-dependent effects of cannabis use on the brain, cognition, and behavior. The study also highlights the need for more evidence on whether stopping cannabis use can reduce the risk of being diagnosed with a mental disorder.
