Perhaps no other branch of cannabis medicine gropes in the dark like that which studies the effect of cannabinoids on a “malfunctioning” human brain.

Today, there is no evidence that cannabis use causes chronic brain disorders, although the complexity of the human brain makes it hard to understand if cannabinoids could instead be effective in treating mental illnesses. When consumed in large doses, cannabis might lead to “psychotic symptoms”, particularly in vulnerable individuals with a personal or family history of mental illness. Yet, a large number of patients with schizophrenia, paranoia, bipolar disorders, and other mental conditions have been self-medicating with cannabis for years.

Doctors in the US who prescribe large amounts of medical cannabis report that very little of it goes to patients with severe psychiatric conditions—with post-traumatic stress disorder being the most common accepted condition. Psychiatrists often advise against cannabis use, while some approve it as a complementary treatment for patients with specific symptoms or diagnoses. Numerous patients report that cannabis relieves some of their symptoms, yet the clinical literature is still underdeveloped, and many studies on the therapeutic use of cannabis for mental health conditions are not of a methodologically high quality.


The role cannabis plays in current psychotherapeutic practices is indeed a complex one. Many patients already feel a sense of stigma surrounding their mental condition, with cannabis only adding fuel to the fire. Healthcare personnel of any level have a duty to protect patients’ private information, and they are not supposed to judge patients’ lifestyles. Conversely, a frank discussion on cannabis use even before starting sessions with a new therapist is highly recommended to help clarify each other’s position regarding the plant.

Therapy should be an opportunity to put oneself out in the open in the company of a caring professional. Any therapist worth their salt should be open to understanding your relationship with cannabis before making any judgment calls. Especially given that cannabis is a lot safer than other drugs patients turn to in times of distress, mental healthcare professionals would be wise not to discredit the herb outright.

On the other hand, the therapists themselves have a tough role. It’s entirely possible, for example, that THC use is causing someone to experience acute anxiety, or that their chronic weed use is keeping them from fulfilling their day to day responsibilities. Again, it’s all about communication.



It is worth mentioning that psychedelic psychotherapies are becoming accepted by the scientific community. Herbs and substances like ketamine, MDMA, ayahuasca, and magic mushrooms are being tested as therapeutic agents against mild or severe mental conditions. Cannabinoids are not psychedelics in a strict sense, yet in countries where cannabis is legal, assisted psychotherapy sessions under the effects of cannabinoids are now offered. For instance, some US states offer cannabis-assisted psychotherapy for around $350, after which a driver is required by law to return you home.

When it comes to mental illnesses, each and every condition requires unique care and treatment. That means that cannabinoids may affect different conditions in distinct ways. Let’s look into some of the research on the developing role of cannabis in mental healthcare.


It’s well-known that THC can make people feel more relaxed, less stressed, and in a better overall mood. Unfortunately, THC can also induce some side effects, particularly in inexperienced or sensitive users. THC is known to trigger anxiety and paranoia at high doses. Intriguingly, CBD is effective at reducing some of these negative psychotropic effects by lowering THC’s ability to bind with CB1 cannabinoid receptors.

While CBD is gaining more and more traction when it comes to future treatments for psychological disorders, THC displays efficacy in its own right—especially regarding bipolar disorders. These conditions involve periods of maniacal high energy, alternating with periods of extremely low mood and depressive episodes. Cannabis use is actually higher in bipolar patients, probably because they use it to alleviate depression and come down from manic episodes as well. The typical biphasic effect of cannabinoids—where different doses produce different effects (ie. sedative vs. uplifting effects)—seems to work well for some patients with this condition.

Nevertheless, and despite promising anecdotes, studies on patients with bipolar disorder or schizophrenia[1] using cannabis have yielded some pretty inconclusive findings, both in gauging the medical efficacy of THC, and its specific use cases. Studies did observe cannabis use was associated with better neurocognitive function in subjects with bipolar disorder, but the opposite was found in the schizophrenic subjects.



CB1 receptors are widespread throughout the brain, and recent neuroimaging techniques have shown increased CB1 receptors in multiple brain regions linked to post-traumatic stress disorder. Cannabinoids affect the hippocampus, an area of our brain that plays a role in learning and memory. This area is important for anxiety disorders like PTSD because it contributes to the mechanisms of danger and safety.

The role of cannabinoids in learning processes related to danger and safety indicates that cannabis can be effective against anxiety and PTSD symptoms. The endocannabinoid system appears to be involved in the extinction of aversive memories, and both THC and CBD have been shown to facilitate the removal of the pathological fear response.

Millions of patients with anxiety disorders report that cannabis provides relaxation, serenity, and a calming effect. PTSD patients specifically report that cannabis helps them with insomnia, anxiety, and mood swings. Still, even here the reports on THC efficacy are varied. Some research says cannabis use alone does not appear to lead to long-term recovery from anxiety disorders or PTSD, yet other studies suggest that cannabis might play some role in a proper treatment. In short, little is known about the effect of cannabis on the natural recovery from anxiety disorders and PTSD.


CBD has been able to treat symptoms of schizophrenia in controlled clinical trials, with results comparable to approved antipsychotic drugs, and with less adverse effects. Because of its non-psychotropic nature, CBD can be experimented with more easily than THC for psychiatric disorders. Research shows that CBD may be effective as an additional therapy for schizophrenia[2], catalysing significantly reduced psychotic symptoms in patients who received a cannabidiol treatment.

Studies also showed that CBD may improve learning and memory for those with cognitive impairments, but its efficacy in improving cognition in schizophrenia cannot be fully confirmed due to lack of clinical evidence. However, CBD has been shown to improve cognition in multiple studies of impairment with preclinical models of schizophrenia, Alzheimer's disease, meningitis, and brain ischemia.



Patients who use cannabis with decent amounts of THC are happy with its lack of side effects compared to common prescription drugs. However, there are some cases where THC has the potential to decrease the effectiveness of other drugs, or even cause unpredictable reactions and worsen the condition. Cannabis has shown to help people who suffer from depression, but using it while on antidepressants can be dangerous as cannabinoids can intensify the side effects. This can also happen with sedatives, alcohol, or other drugs, as patients may feel overly sedated when consuming THC together with a tranquiliser.

CBD is non-psychotropic, and it also has the potential benefit of helping break addiction[3] to specific deadly substances. However, cannabidiol can prevent the proper metabolisation of many pharmaceutical drugs. CBD is metabolised by cytochrome P450 enzymes; it then essentially deactivates these enzymes, preventing them from effectively metabolising other drugs. This is crucial to understand for those individuals taking certain medications—like some antipsychotics—as it can result in more pronounced side effects.


The peculiar interactions between cannabinoids and our mind are far from being understood. The lack of comprehensive, large-scale studies makes it exceedingly difficult to draw conclusions on a psychological or psychiatric perspective. Cannabinoids might help with some mental conditions, but they also might increase some symptoms or worsen a therapy. Furthermore, we are far away from knowing the optimal doses and standard methods of cannabis administration for psychiatric use.

Despite our present lack of knowledge, cannabinoids are seen as greatly promising since they target different neurotransmitter systems than traditional drugs, with the potential of being more effective and less disruptive.

External Resources:
  1. Opposite Relationships Between Cannabis Use and Neurocognitive Functioning in Bipolar Disorder and Schizophrenia - PubMed
  2. Psychiatry Online
  3. Cannabidiol as an Intervention for Addictive Behaviors: A Systematic Review of the Evidence
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