The addiction expert Univ.-Prof. Dr. Otto Lesch has long advocated for a factual debate, a broader range of cannabis-based medicines, and accompanying clinical research. We spoke with the specialist at the Medical University for Psychiatry and Psychotherapy and Board Member of the International Academy of Law and Mental Health about the following topics:
- the clinical data on the effectiveness of cannabis,
- common myths such as “cannabis causes schizophrenia” and
- the consequences of a failed prohibition policy.
Professor Lesch, in your studies, you were able to refute the thesis that the flowers of the Cannabis sativa plant are a gateway drug to harder substances. Why does this prejudice persist so stubbornly?
Since 2002, we have conducted several waves of research, surveying and drug testing 8,000 adolescents around the age of 18. We have published the factors correlated with substance use and how these substances interact in top journals. The primary reason for initiating the use of psychoactive substances is psychological factors, such as a cyclothymic or irritable temperament or the presence of ADHD. If there is such a thing as a gateway drug, it is nicotine. Nicotine, like alcohol, leads to rapid dependence. Cannabis with a low THC content is less likely to cause rapid dependence in this regard. The real problem lies elsewhere: we have 18,000 direct tobacco-related deaths and 8,000 direct alcohol-related deaths annually, but not a single cannabis-related death. The tobacco and alcohol lobby loudly defines an external enemy to distract from their own harmful effects. They employ so-called experts who have rarely or never published scientific work on this topic but are familiar with addicts from their daily work and view everything from a very biased perspective.
Is the term cannabis addiction being misused?
Yes, both by the tobacco and alcohol lobby and by individuals who profit from cannabis sales. The more pronounced the “shady” image of the hemp plant is, the greater the interest among adolescents in consuming cannabis. The clearer the stance that hemp is a fibrous, fast-growing, and ubiquitous plant that can be used medically as ointment and medication, the less interesting it becomes for mass consumption by adolescents. Unfortunately, this has not yet been understood by the policymakers in Austria.
Your colleague, addiction medicine specialist Kurosch Yazdi, claims there is an increase in cannabis-associated schizophrenia. How do you evaluate these statements?
Schizophrenia, a primary thought disorder that occurs in adolescence, shows very similar prevalence rates epidemiologically around the world (0.6 to 1.0 percent), regardless of whether cannabis is smoked in these regions or not. The multifactorial causes are both genetic and toxic (such as infections or poisoning from tobacco during pregnancy). Cannabis does not play a significant role in the cause of schizophrenia. Schizophrenic adolescents, particularly those experiencing concentration problems and feelings of emotional numbness, often attempt self-medication with cannabis. For some, this helps, but this area needs much more research. Many studies suggest that cannabis products containing cannabidiol (CBD) can have a protective effect, while the risk of psychosis is more likely associated with products that have a very high THC content. This is yet another reason to prefer controlled cannabis plants with clearly defined ingredients, rather than promoting illegal cannabis use with unknown, sometimes toxic concentrations. A prohibition policy always creates a taboo, thereby hindering education and prevention efforts.
How would you outline the current state of research on cannabis?
For both polyneuropathy and as an adjunct to chemotherapy, there are already sufficient clinical data demonstrating positive effects. All other indications have completed Phase 2 studies but have not undergone prospective Phase 3 and 4 studies. However, experts from various fields have reported positive examples from their practice. Especially for severely ill patients, none of the experts wanted to forgo cannabis in flower form, as its rapid pain-relieving and relaxing effects have not been matched by any other product in terms of intensity. Clinical research on this is already underway.
What makes clinical studies on the efficacy of the medicinal drug Herba Cannabis difficult?
The dosage is often not stable, and the composition of individual cannabinoids can vary significantly. We are currently mixing four different cannabinoids in varying amounts and conducting Phase 1 studies with them. If cannabinoids prove effective in practice, they would likely be significantly more cost-effective than the currently used medications. This is also a reason why the pharmaceutical industry is not very active in this area. A high-price policy with corresponding returns cannot be achieved with cannabis.
From your medical experience, where do cannabinoids have a legitimate place in therapy?
From my psychiatric perspective, they have a place in the treatment of epilepsy, spasms, neurological diseases, and in end-of-life care. No matter how much they also act as anxiolytic and antidepressant, this still needs to be demonstrated in studies. For some process psychoses with the central symptom of sensory gating disturbance — meaning, all sensory impressions are equal and the patient cannot focus on any one impression — I already use Dronabinol with good success.
Denmark is testing a program for medical cannabis, while in Germany, the doctor and Health Minister Karl Lauterbach is planning cannabis liberalization for 2023. The addiction and drug coordinator of the city of Vienna, Ewald Lochner, also sees a need for action. Austria’s politics remain inactive.
This inaction can be seen in many prevention programs. There is a perception that politics is closely tied to the tobacco and alcohol industries, while simultaneously targeting cannabis as the external enemy. The pharmaceutical lobby certainly plays a role as well. Israel has successfully demonstrated over the past few decades how cannabis should be utilized in medicine. I would recommend this approach to the federal government as well: Cannabis should be legally treated like tobacco, alcohol, and sedatives. Cannabis sativa is not a recreational substance but contains pharmacologically active compounds that should be in the hands of a professional, such as a doctor or pharmacist.
Has current cannabis policy failed?
Yes. We should use cannabis in medicine and promote its applications. This requires a broad availability and liberalization. We need cannabis medications for people with spasms, severe polyneuropathies, and the tough skin of elderly men. This way, no young person would see cannabis as something special anymore.