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The Unjustifiable Delay: Addressing the Absence of the Endocannabinoid System in Medical Textbooks and Education


The endocannabinoid system (ECS) is a vital and intricate biological network that plays a critical role in human health and disease, influencing a myriad of physiological processes, including pain, inflammation, mood, appetite, metabolism, and neuroprotection [1]. Despite its significance, our previous article revealed a concerning omission: the ECS has been largely excluded from medical textbooks, including the widely respected “Guyton and Hall Textbook of Medical Physiology.” This glaring absence underscores the need for immediate action to address the gap in medical education. The purpose of this article is to further emphasize the unprecedented and unacceptable delay in including the ECS in medical textbooks and education, and to advocate for its prompt and comprehensive incorporation into the medical curriculum. By doing so, we aim to equip future medical professionals with a more complete understanding of human physiology and facilitate better patient care.

Comparing the ECS with other systems

The inclusion of the endocannabinoid system in medical textbooks is taking significantly longer than that of other physiological systems. Many other systems, such as the immune, endocrine, and nervous systems, have been promptly incorporated into medical education following their discovery, reflecting their significance in maintaining health and their impact on various diseases. Interestingly, the ECS shares similar, if not more critical, roles in maintaining health and modulating a wide range of physiological processes.

For instance, the ECS plays a crucial part in maintaining homeostasis, ensuring that the body’s internal environment remains stable despite external changes. It interacts with other systems, such as the nervous, immune, and endocrine systems, to regulate inflammation, neuroprotection, and metabolic processes [1]. Furthermore, it has been implicated in the pathophysiology of numerous diseases, including obesity, diabetes, neurodegenerative disorders, inflammatory disorders, psychiatric disorders, and cancer [1].

To further study the relative importance of the ECS during the last 20 years, I conducted a bibliographic analysis of eight different physiological systems. In detail, I performed a title-based search on PubMed (e.g. “”endocannabinoid system”[Title]”) and restricted the results to articles published between 2002-2022. To add objective and relevant information to the table, I used the free software ‘Publish or Perish’ and Google Scholar to generate objective estimates of the number of total citations and h-indexes for the different physiological systems. 1000 publications (max allowed) published between 2002-2022 were included for each physiological system.

Bibliometric Analysis

Physiological SystemTitle-based Publications
Total Citations* (Google Scholar)h-index*
(Google Scholar)
Endocannabinoid System1,20176,843138
Digestive System95838,12177
Immune System7,985354,807309
Endocrine System37423,84874
Cardiovascular System2,088103,097167
Respiratory System90935,62883
Lymphatic System37323,88576
Nervous System26,875336,911306
*based on 1000 articles from Google Scholar between 2002-2022

Looking at the table, we can make several observations and draw conclusions about the research output and relevance of the ECS in comparison to other physiological systems:

  • The number of publications on the ECS (1,201) is lower compared to some other physiological systems like the Immune System (7,985) and the Nervous System (26,875), but it is comparable to or higher than the Digestive System (958), Endocrine System (374), Cardiovascular System (2,088), Respiratory System (909), and Lymphatic System (373). This suggests that the ECS is a topic of significant interest within the scientific community and should be considered as an essential part of medical education.
  • The total citations for the Endocannabinoid System (76,843) indicate that research on this system has made a substantial impact on the scientific community. Although the total citations for the ECS are lower than those for the Immune System (354,807), the Nervous System (336,911), and the Cardiovascular System (103,097), the number of citations is considerably higher than that for other systems like the Digestive, Endocrine, Respiratory, and Lymphatic Systems.
  • The h-index for the Endocannabinoid System (138) is relatively high compared to some other physiological systems, such as the Digestive System (77), Endocrine System (74), Respiratory System (83), and Lymphatic System (76). This high h-index indicates that research on the ECS has had significant influence and recognition in the scientific community, further supporting the argument for including it in medical education and textbooks.

In conclusion, the bibliometric analysis strongly supports that the ECS is an important area of research with a considerable impact on the scientific community. Despite the relatively lower number of publications compared to some other physiological systems, the high total citations and h-index for the ECS demonstrate its relevance and significance. The exclusion of the ECS from medical textbooks and education is therefore not only unprecedented but also unacceptable, given its importance in human physiology.

ECS’s importance in understanding medical cannabis

The lack of education on the ECS not only compromises the understanding of human physiology but also hinders the proper utilization of medical cannabis, a field that has been gaining considerable attention in recent years. Medical cannabis, with its diverse applications, has the potential to treat a myriad of conditions, ranging from chronic pain and epilepsy to multiple sclerosis and cancer-related symptoms. A thorough understanding of the ECS is essential to fully comprehend the complex mechanisms underlying the therapeutic effects of medical cannabis and to optimize its use in various clinical settings.

Alarmingly, recent surveys have demonstrated that a significant percentage of medical residents, fellows, and medical school deans feel utterly unprepared to prescribe medical cannabis or believe their graduates are inadequately trained to do so [2][3][4].

A Canadian study from 2022 focused on exploring attitudes and beliefs of pain physicians regarding medical cannabis for the management of chronic noncancer pain [5]. Despite increasing use of medical cannabis for chronic pain among Canadians, the study found that pain physicians expressed concerns regarding the evidence to support this therapy and acknowledged important barriers to access. This suggests a lack of knowledge and education among physicians on the potential benefits and risks of medical cannabis. Furthermore, a recent survey conducted in Denmark, a country with an ongoing medical cannabis pilot program since 2018, similarly showed that a significant proportion of general practitioners (GPs) lack knowledge and hold negative attitudes towards the prescription of medical cannabis to their patients [6]. 

Better understanding of the ECS can lead to more effective and targeted use of medical cannabis in numerous therapeutic applications. By identifying the specific receptors, enzymes, and endogenous ligands involved in the ECS and their interactions with various phytocannabinoids, healthcare professionals can better tailor treatment plans to individual patients’ needs. This knowledge may also contribute to the development of novel cannabis-based therapies and the refinement of existing treatment modalities.

In conclusion, a more in-depth understanding of the ECS is crucial not only for comprehending human physiology but also for optimizing the use of medical cannabis in various therapeutic applications. By incorporating the ECS into medical education, future healthcare professionals can be better equipped to navigate the rapidly evolving landscape of medical cannabis, ultimately improving patient care and advancing therapeutic options.

Dispelling misconceptions and stigma surrounding the ECS

One of the potential reasons for the exclusion of the ECS from medical textbooks and education could be the bias or stigma associated with cannabis research. Historically, cannabis has been a controversial substance due to its psychoactive properties and potential for abuse, which has led to societal and legal restrictions on its study and use. Consequently, this negative perception might have inadvertently hindered the recognition and understanding of the ECS, despite its critical role in maintaining human health.

It is essential to clarify that the ECS, as a physiological system, is not controversial. While it is true that the ECS was discovered through research on the pharmacological effects of cannabis, its connection to cannabis should not be a barrier to its inclusion in medical education. The ECS is a vital component of human physiology, regulating numerous essential processes such as appetite, mood, pain perception, and immune function, among others. It is crucial to emphasize that the ECS’s physiological functions go well beyond its interactions with cannabis, and understanding its role is vital for any healthcare professional.

To facilitate the inclusion of the ECS in medical education, it may be necessary to reframe its role and dissociate it from the stigma surrounding cannabis. One potential approach could be to rename the ECS, focusing on its primary function, such as the “Homeostatic System” or the “Master-Regulatory System”, or a similar term that highlights its role in maintaining homeostasis and devoid of  unfortunate connotations to cannabis. This strategy could help overcome the historical bias and stigma and allow for a more objective evaluation of the ECS’s importance in medical education.

As an allegory to emphasize the absurdity of considering the ECS controversial, consider the discovery of neurotransmitters, such as dopamine and serotonin, and their role in the nervous system. Despite their associations with recreational drugs, such as cocaine and MDMA, that can lead to addiction or abuse, neurotransmitters have been widely accepted and integrated into medical education due to their essential role in human health. Similarly, the ECS should be recognized and incorporated into medical curricula, regardless of its association with cannabis, because of its undeniable significance in human physiology. By reframing the ECS’s role and possibly renaming it, future healthcare professionals will be better equipped to understand its relevance and utilize this knowledge to advance patient care.

The consequences of delayed ECS education

The continued exclusion of the ECS from medical education carries several potential negative impacts, including missed therapeutic opportunities and inadequate patient care. A comprehensive understanding of the ECS is crucial for healthcare professionals, as it plays a significant role in numerous health conditions and can potentially influence treatment outcomes.

For instance, a better understanding of the ECS could lead to improved treatment options for chronic pain. The ECS is involved in modulating pain perception, and targeting this system has been shown to be effective in reducing pain without the risk of addiction or severe side effects associated with opioids [7]. By incorporating the ECS into medical education, physicians may be better equipped to recommend alternative therapies for pain management that are both effective and safe.

Another example is the potential role of the ECS in treating neurodegenerative diseases like Alzheimer’s and Parkinson’s. Research suggests that modulating the ECS could help reduce neuroinflammation and slow down the progression of these diseases [8]. However, without proper education on the ECS, healthcare professionals may overlook the potential benefits of targeting this system in managing these debilitating conditions.

Moreover, the ECS plays a critical role in regulating immune function, and its dysregulation has been implicated in various autoimmune and inflammatory diseases [9]. A better understanding of the ECS could help healthcare professionals design more targeted and effective treatments for patients suffering from these conditions.

Examples of improved patient care

A better understanding of the ECS has led to improved patient care in several ways. For example, targeting the ECS has shown to be effective in reducing chronic pain perception without the risk of addiction or severe side effects associated with opioids [10]. In addition, modulating the ECS has shown potential for treating neurodegenerative diseases like Alzheimer’s and Parkinson’s by reducing neuroinflammation [11]. Furthermore, research has shown that the ECS plays a critical role in regulating immune function, and its dysregulation has been implicated in various autoimmune and inflammatory diseases [12]. A better understanding of the ECS has led to the development of more targeted and effective treatments for these conditions, ultimately leading to better patient outcomes.

A call to action

Given the far-reaching implications of the ECS in human health and the potential benefits of medical cannabis, it is imperative that medical schools, textbook publishers, and educators acknowledge the importance of the ECS and swiftly incorporate it into their curricula. The exclusion of the ECS from medical education is both unprecedented and unacceptable, as it hinders the development of comprehensive treatment strategies and limits the potential for improved patient care.

It is essential for impactful medical cannabis associations such as the International Association for Cannabinoid Medicines (IACM), the Medical Cannabis for Clinicians Society (MCCS), and the Americans for Safe Access (ASA), as well as the growing grassroots movement of individuals worldwide, to focus on advocating for the inclusion of the ECS in medical education. By removing the stigma and acknowledging the ECS’s critical role in human physiology, we can promote better patient care, advance therapeutic options, and facilitate the proper use of medical cannabis. It is time to come together as a community and recognize the importance of educating healthcare professionals on the ECS, and these associations and individuals can play a vital role in achieving this goal.

To expedite the process of including the ECS in medical education, it is recommended that advocates lobby for the inclusion of the ECS in accreditation standards for medical schools. This approach would ensure that future healthcare professionals receive adequate education on this vital physiological system, equipping them with the knowledge necessary to utilize medical cannabis effectively in their clinical practice.

Alternatively, developing standalone courses focusing on the ECS and its clinical implications may serve as a temporary solution to bridge the knowledge gap. While this approach is not the preferred long-term strategy, it could help to raise awareness among healthcare professionals and stimulate a broader conversation on the importance of the ECS in medical education.

Ultimately, the integration of the ECS into medical curricula is essential for the advancement of cannabinoid medicine and the optimization of patient care. By embracing the ECS’s critical role in human health and disease, medical professionals can better understand and harness the therapeutic potential of medical cannabis, resulting in improved treatment options and better patient outcomes. The time has come to put an end to the unjustifiable delay and ensure that the ECS takes its rightful place in medical education.


In summary, the endocannabinoid system (ECS) is a vital component of human physiology, impacting numerous processes and playing a significant role in health and disease. Despite its critical importance, the ECS has been inexplicably omitted from medical education, creating an alarming gap in knowledge with potentially far-reaching consequences for patient care and therapeutic progress. This oversight is both unprecedented and unacceptable, particularly when considering the potential benefits of medical cannabis when applied with a deep understanding of the ECS.

The Hippocratic Oath, a guiding principle for physicians, emphasizes the duty to stay abreast of advancements in medical knowledge. Doctors are morally obliged to provide the best possible care for their patients, which certainly must include incorporating new discoveries in human physiology. Ignoring a non-controversial discovery such as the ECS, which was made over three decades ago, is indefensible and incompatible with the ethical standards of the medical profession.

The urgency for collective action cannot be overstated. Medical schools, textbook publishers, educators, and healthcare professionals must work together to ensure that the ECS receives the attention and recognition it deserves in medical education. By doing so, we can equip future healthcare providers with the necessary knowledge to make informed decisions regarding medical cannabis and its applications. It is time to rectify this glaring omission and integrate the ECS into the fabric of medical education, paving the way for enlightened therapeutic strategies and improved patient outcomes.

Stefan Broselid, Ph.D.
Editor-In-Chief, Aurea Care Medical Science Journal


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