The Mediating Role of Personality Traits in Psychedelics’ Relationships with Nature Connectedness and Pro-Environmentalism

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Abstract

In a world where a global climate crisis continues to grow more disturbing, societal inaction to combat such a crisis is worrying. However, some emerging research has revealed a possible solution. Studies by Kettner, Forstmann, Lyons, and others have found that psychedelics such as psilocybin, LSD, and ayahuasca exhibit positive association with nature-relatedness (NR) and pro-environmentalism. Unfortunately, studies in this area of research are limited, and the mechanisms underlying the relationship between psychedelics and NR are not fully understood. This review endeavors to understand how personality traits associated with psychedelics and NR play a mediating role in linking them together. To accomplish this goal, experimental evidence on this topic, such as psychedelics’ relationship with certain personality traits, was critically examined. The present review hypothesizes that commonly used psychedelics psilocybin, LSD, and ayahuasca acting on overlapping serotonergic pathways mediate conserved changes in aspects of personality such as Openness to experience, ego-dissolution, and liberal political views that underlie their positive role in promoting nature-relatedness and facilitating pro-environmental behavior.

Introduction 

The ‘60s and ‘70s in the United States of America were characterized by a wide array of protests. From anti-war demonstrations to civil rights, the ‘60s and ‘70s were filled with dissent. Especially noteworthy was the counterculture of the 1960s. A specific group of people during this period, known as “hippies”, were characterized by their use of hallucinogenic drugs. According to the National Household Survey on Drug Abuse, in 1972, 5% of all Americans had undergone at least one encounter with psychedelics in their lifetime1. By 1979, this statistic skyrocketed to 25%1. Additionally, one of today’s most noteworthy drugs, Lysergic acid diethylamide (LSD), which was synthesized in the ‘30s, first popularity in the ‘60s. The counterculture brought psychedelics to the fore of public perception and helped kick-start investigations examining the drugs’ broad effects on personality and mental health. Research involving psychedelics was largely unheard of until the mid-60s (Figure 1). “Hippies” were known not only for their interest in recreational psychedelic drug use but also for their passion for environmental conservation. While the two stereotypes might seem unrelated, recent studies by Forstmann and Sagioglou (2014), and Lyons and Carhart-Harris (2016) have shown there might be a positive association between psychedelic use and eco-friendly habits2,3. However, it must be noted that there is a current lack of an established causal psychedelic-NR relationship. The highly subjective nature of psychedelic experiences is poorly suited to model in experimental conditions where causality can be inferred and effects can be consistently reproduced. The absence of large-scale double-blind randomized clinical trials limits the study of the effects of psychedelics on pro-environmentalism to correlational inferences. Thus, we will not be drawing conclusions about potential causal relationships between psychedelics and pro-environment behavior.  At the time of this writing, little is understood about the mechanisms that help mediate the psychedelic-NR relationship. To help fill this gap, the present research aims to discover the role of personality trait alterations underlying the relationship between psychedelics and increased NR. Which specific personality traits does the usage of common psychedelics induce and might these traits connect to emerging evidence of the benefits of psychedelic usage on pro-environmentalism? To answer this question research will be done on personality traits that have positive associations with both psychedelics and NR. The paper will then make tentative observations concerning the relationships discovered.

 Psychedelics are a psychoactive (affecting the mind or behavior) class of drugs that may induce hallucinations, alter comprehension, and influence the emotions of users4. However, there is another less well-known effect of psychedelics: an increase in pro-environmentalism. Pro-environmental behaviors are defined as proactive behaviors that help minimize the harm done to the environment5. Examples of pro-environmental behaviors include choosing ‘green’ transportation (such as walking, biking, or skating), recycling trash, reducing use of single-use disposable plastics, and cutting down on meat consumption. Pro-environmental behaviors are also heavily associated with nature-relatedness (NR), which refers to one’s connection with nature6. Increased NR has been shown to benefit many aspects of an individual’s life. From reducing anxiety to improving life satisfaction, NR aids individuals in many areas, such as psychological health and personal well-being6,7. Psychedelic usage alone has shown potential in alleviating symptoms of treatment-resistant depression, obsessive-compulsive disorder (OCD), and even anxiety associated with terminal cancer8. Given psychedelics’ promising results in inducing pro-environmental behaviors, researchers believe that these drugs could be utilized to increase awareness and proactiveness concerning environmental concerns9. However, at the time of this writing (2023), there is a severe lack of research regarding the topic of psychedelics and changes in attitude towards nature, especially in comparison to other areas of psychedelic research (Figure 1). Therefore, further studies in this field are essential to increasing both awareness of this concept and new knowledge. The present review will focus on the underlying personality traits that relate to the emerging evidence regarding the connection between common psychedelic use and pro-environmentalism/NR. While other reviews have critically examined empirical studies on psychedelics and pro-environmentalism literature they neglect to investigate literature regarding the personality traits mediating such changes in pro-environmental behavior. This is a critical gap in the literature as although the association between psychedelics and pro-environmentalism has been acknowledged, the mechanisms behind the association are unknown; examining mediating factors in the psychedelic-NR relationship could therefore help researchers progress in their understanding of the workings behind psychedelics’ effect on pro-environmentalism.  To successfully carry out a focused analysis of personality traits’ role in psychedelic-NR relationships, drugs lacking the potential to alter a user’s pro-environmental outlook fall outside the scope of this review. Therefore, this review will discuss the effects of psilocybin, ayahuasca, and LSD.  Additionally, there is a severe lack of studies experimentally investigating the psychedelic-NR relationship. At the time of this writing, there are only 7 studies that fit this category (Table 1). The scarcity of psychedelic-NR relationship research is especially evident when compared to the abundance of other psychedelic relationship research. For instance, while the keyphrase “Psychedelics and Nature Relatedness” yields less than 3000 results on the Google Scholar search engine, the phrase “Psychedelics and Anxiety” yields more than 13,000 results (Figure 1). Therefore, in the interest of including all available research, this review will include studies from all available demographic populations and geographic locations. The present research aims to discover the role of personality trait alterations underlying the relationship between psychedelics and increased NR. Which specific personality traits does the usage of common psychedelics induce and might these traits connect to emerging evidence of the benefits of psychedelic usage on pro-environmentalism? To answer this question research will be done on personality traits that have positive associations with both psychedelics and NR. The paper will then make tentative observations concerning the relationships discovered.

Figure 1: Citation Counts for Database Search Terms Relating to Psychedelics from years 1955-2020. A database search (Google Scholar) of keywords “Psychedelics and Anxiety”, “Psychedelics and Depression”, “Psychedelics and Crime”, “Psychedelics and PTSD” and “Psychedelics and Nature Relatedness” was performed in five-year bins to obtain citation counts for particular search terms. Citation counts for “Psychedelics and Anxiety” (red), “Psychedelics and Depression” (blue), and “Psychedelics and Crime” (black), began to rise in the mid-1960s, with an early peak around 1975. Conversely, “Psychedelics and PTSD” and “Psychedelics and Nature Relatedness” only showed increases from the year 2000, indicating a shifting trend in the focus of psychedelic research towards PTSD and Nature Relatedness.

Introducing Psychedelics

Psychedelics, commonly known as hallucinogens, are defined as a class of psychoactive substances that are involved in the treatment of psychiatric disorders such as depression and anxiety10. All psychedelics act as agonists at 5-hydroxytryptamine receptors (5-HT, commonly known as serotonin receptors). This means that the drugs can mimic the neurotransmitter serotonin, and as a result, may activate the same receptors as serotonin (5-HT/serotonin receptors).  While most psychedelics interact with the 5-HT2A receptor, some specific psychedelics also interact with other 5-HT receptors including but not limited to the 5HT1A, 5HT2B, and 5HT2C receptors. 5-HT receptors can help support tasks such as regulation of neuronal activity or behavioral change11.

Psychedelics’ specific interaction with serotonin receptors underlies the spectrum of symptoms from their usage. 5-HT receptor signaling is heavily involved in mood and anxiety regulation. Therefore, it is not unexpected that psychedelics are heavily associated with the treatment of psychiatric disorders such as depression, anxiety, and OCD10. Drugs such as psilocybin, ayahuasca, and LSD are among some of the best-studied psychedelics in use today. 

Psilocybin, known by its street name “magic mushrooms”, is an organic compound found in many mushrooms belonging to the genus Psilocybe8. Like many other psychedelics, psilocybin interacts with the 5-HT2A receptors and additionally acts as 5HT1A and 5HT2C agonists12. Due to the hallucinogen’s interaction with these receptors, psilocybin is well known for inducing a state of altered consciousness, thought disorder, and perceptual alterations8. Additionally, clinical trials have shown psilocybin’s potential use in treating and reducing symptoms of psychiatric illnesses such as end-of-life anxiety, treatment-resistant depression (TRD), and even tobacco-use disorder. These effects have been shown to last as long as 9 months, 3 months, and 12 months, respectively13,14,15. We speculate that psilocybin may contribute to longer-lasting symptoms of NR compared to LSD and ayahuasca due to the long-lasting aspect of certain psilocybin-induced effects such as reduction of end-of-life anxiety and tobacco-use disorder.

LSD, more commonly known by the name “acid”, is a synthetic psychedelic, unlike psilocybin or ayahuasca which are both derived from organic hosts such as mushrooms or the stems, leaves, and vines of specific plants. Along with its affinity for 5-HT2C and 5-HT1A receptors, LSD binds with dopamine receptors D1 and D412. Common effects of LSD use include reducing problematic drinking behavior and treatment of mood disorders including major depressive disorder (MDD) and generalized anxiety disorder. Chi and Gold (2020), and Hollister, Shelton, and Krieger (1969) have done studies that compare LSD to other drugs such as dextroamphetamine and naltrexone in efficacy at helping treat alcohol use disorder (AUD). Their results show that LSD produces similar, if not more promising effects in reducing harmful habits and increasing abstinence8,16. The effects of LSD lasted up to 6 months after administration, and over half of the 72 patients reached personal goals of sobriety after 38 weeks8,16. LSD has also shown promising clinical results for mood disorder symptoms. In a study involving 12 patients with anxiety associated with terminal illness, results showed an increasing trend towards reduction of anxiety17. Due to an overlap between LSD and psilocybin symptoms (efficacy in reducing substance dependency and MDD), we speculate that the two psychedelics will show similar degrees of success concerning positive association with NR.   

Ayahuasca is another well-known psychedelic, historically known for its use in religious and spiritual ceremonies by indigenous peoples of the Amazon Basin and other South American cultures8. Ayahuasca is a brew mainly composed of two plants with the active chemical N,N-Dimethyltryptamine (DMT)8. Ayahuasca interacts with receptors such as 5HT1A, 5HT2A, and 5HT2C18. Common effects of ayahuasca consumption include feelings of connection and unity, intense hallucination, and introspection. While scholars have examined the potential of ayahuasca in reducing symptoms of psychiatric disorders, at the time of this writing, more research must be done to confirm ayahuasca’s efficacy in treating psychiatric disorders8. Due to a current lack of research exploring ayahuasca’s potential as a therapy (8090 results using the phrase “ayahuasca therapy” versus 21800 results using the phrase “psilocybin therapy” in the search engine Google Scholar at the time of this writing), we are unsure of the degree of effectiveness ayahuasca will have on NR in comparison to the other psychedelics psilocybin and LSD.   

Psychedelics can treat many conditions and even relieve substance reliance. An effect that contributes to these results is the way psychedelics change or influence users’ personalities. 

Psychedelics Impact On Personality

Given their broad activation of mood-regulating receptors/circuits in the brain, it is unsurprising that psychedelics also heavily influence users’ personalities. Some of the most common personality changes exhibited by psychedelic users include increases in Openness to experience, ego-dissolution, and liberal political views1,4

For instance, the recreational use of psilocybin is notable for its association with an increase in Openness19. Past studies by Erritzoe and Nour discovered that compared to the lifetime use of other drugs such as Midomafetamine (MDMA), psilocybin had a significant impact on Openness to experience. Patients who showed a preference towards psychedelic use compared to a preference towards MDMA use demonstrated higher levels of Openness19. Another study that used online surveys to collect information compared the changes in the personality of those with lifetime psychedelic use as opposed to those with regular alcohol consumption20. Where alcohol use found a decrease in Openness and NR, psychedelic use positively predicted the two traits20. Additionally, trials that used LSD rather than psilocybin showed similar results. The group consisted of 12 patients with prior experience with psychedelics; some of the patients were given 75 micrograms of LSD, while others were simply given a placebo21. At a two-week follow-up, the researchers observed a significant increase in Openness in the participants21. Although there was some evidence to support a significant relationship between ayahuasca and Openness, the findings were not consistent. One study done in 2020 supports a positive association between ayahuasca and Openness. The study evaluated self-reported questionnaires from volunteers who attended an ayahuasca ceremony to complete data analyses. After analyzing the questionnaires, the researchers found a trend toward a significant increase in Openness six months after the ayahuasca ceremony22. However, a 2021 paper that tests ayahuasca’s effect on personality discovered conflicting results with the 2020 study. The 2021 paper involved two trials of ayahuasca administration involving different groups of participants. Both trials involved 15 volunteers, but only the second group of volunteers showed a significant increase in Openness after ayahuasca administration23. Therefore, due to varying results, it is uncertain if ayahuasca has a significant association with Openness.

 An additional change in personality heavily associated with psychedelic use is ego-dissolution, a common effect described as a loss of boundaries separating the self from others, feelings of unison, and awareness of an expansive universe20. In a study with a total sample of 893 participants, a subset of the participants were asked a series of questions about the intensity of their ego-dissolution experience while under the psychedelic influence20. The study used a scale from 0-100 (0 being “not at all”, and “100 being the most intense imaginable”), and the median intensity was 76, showing that many of the participants felt high levels of ego-dissolution during their psychedelic experiences20. The same study also discussed the relationship between intense feelings of ego-dissolution and other personality traits. For instance, ego-dissolution positively predicted NR and Openness, while negatively predicting authoritarianism. 

Along with Openness to experience and ego-dissolution, psychedelic use is often associated with changes in political views. A study by Nour, Evans, and Carhart-Harris that used anonymous internet surveys found significant contrast in the political views that alcohol consumption is correlated with compared to psychedelic use20. The study found that while alcohol consumption positively predicted authoritarian views, naturalistic psychedelic use negatively predicted authoritarianism. Also, where alcohol consumption negatively predicted liberal views, psychedelic use positively predicted liberalism20. A clinical study led by Lyons and Carhart-Harris which administered doses of psilocybin to patients with TRD found similar results. Data was collected one week and 7-12 months after the final doses (2 doses in total, the first one was 10 mg and the second was 25 mg) were distributed. The results showed that the patients experienced a significant decrease in authoritarianism one week after the last dose was administered, with effects persisting up to 12 months3. Based on the results of Nour, Evans, and Carhart-Harris (2017) and Lyons and Carhart-Harris (2018), we speculate that liberal political opinions are positively aligned with psychedelic use while authoritarian political views are negatively aligned with psychedelic use.

Psychedelics can also induce unique sets of well-studied effects on personality which are distinct from the changes induced by the use of non-psychedelic drugs like alcohol or cocaine20. Certain psychedelics are linked with certain personality changes. Likewise, specific personality traits are correlated with ecological behaviors. 

Personality Traits’ Correlation with Positive Ecological Behaviors

The Big Five personality traits, consisting of Openness to experience, Conscientiousness, Extraversion, Agreeableness, and Neuroticism, are one of the most commonly employed personality trait taxonomies. The Big Five overlap with some of the most commonly seen personality traits associated with psychedelic use. Psilocybin and LSD users typically exhibit higher levels of the personality trait ‘Openness to experience’21. Likewise, the personality change of ego-dissolution shares a positive relationship with Openness24. Interestingly, liberalism, which is positively linked to psychedelic use, has shown positive associations with the Big Five trait ‘Conscientiousness’25

Some personality traits can influence one’s pro-environmentalism and likelihood of showing positive ecological behaviors. Certain traits are oftentimes related to high levels of connectedness with nature (CN), a measure highly associated with pro-environmentalism26. CN, while not a personality trait, is defined as the measure of how closely humans feel towards non-human living beings such as plants and animals27.  CN is measured by using a 14-item Connectedness to Nature Scale developed by Mayer and Frantz27,28. CN and NR help to link together specific personality traits with ecological behaviors. The relationship between personality traits and NR is a hotly debated topic in the field of psychology, but a causal relationship has not yet been acknowledged or established27. The following sections will critically examine the evidence supporting the association of each Big Five trait with positive ecological behaviors. 

The Big Five trait most consistently and strongly associated with CN and positive ecological behaviors is Openness to experience. In one of the seminal studies of this association, Markowitz et al. (2012) investigated the relations between broad personality traits and pro-environmental actions of two groups, one composed of 778 adults 18-85 years old recruited through mail solicitations, and the other composed of 115 undergraduates from a public university in the United States of America. The large majority of participants in the first sample were Caucasian, however, their highest level of education varied28. The authors developed the Environmental Practices Scale (EPS) as a measure of environmental behaviors. Results from the first group show that the top ten facets of Big Five traits that correlated with the EPS were all facets of Openness, leading the researchers to conclude that certain facets of Openness strengthen the correlation with pro-environmentalism. For example, those who reported an appreciation for aesthetics, were creative, and had a large range of interests (all facets of Openness), were also more likely to self-report involvement in pro-environmental behaviors28. The researchers also examined the correlations between the EPS with three different well-validated personality inventories (NEO, HEXACO, 6FPQ) each with a variety of domains. All three inventories had an Openness domain. The research results showed that out of all seventeen of the tested domains, the domains with the highest zero order (bivariable correlation without controlling for the influence of other variables) and partial scores (bivariable correlation with control over the influence of other variables) were Openness domains. Additionally, the Openness domains were the only domains to have a p-value of less than or equal to 0.001, telling researchers that there is only a 1 in 1000 chance that the results were due to random chance, demonstrating the reliability of the results. Not only that, past research has firmly established the relationship between appreciation for the natural world (aesthetics) and the likelihood of pro-environmental behaviors28. In the second sample, the authors found that only Openness to experience showed consistent and strong positive correlations to pro-environmental behaviors28. The authors used three different scales: The 15-item New Ecological Paradigm Scale (NEP), the 14-item Connectedness to Nature Scale (CNS), and the 24-item Student Environmental Behavior Scale (SEB). Markowitz et al. used these three scales to measure pro-environmentalism and then used the Big Five personality inventory to assess the relationship between certain domains and facets and pro-environmentalism. Markowitz et al. discovered that out of all five domains (Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism), only Openness displayed a significant positive correlation to pro-environmentalism. Openness’s zero-order correlation with the SEBS was 0.23, with Openness’s facet “Aesthetics” displaying a positive correlation of 0.27. The only facet with a correlation close enough to compete with Aesthetics was Self-discipline. However, Self-discipline did not positively or significantly correlate with the NEP or CNS. Openness’s correlation with the NEP was the strongest of all the domains, displaying a correlation of 0.30. Finally, Openness along with its facets (Aesthetics and Ideas) had the strongest correlation with the CNS compared to the other tested domains and facets. The results from the research displays Openness’s strong and consistent relationship with ecological behaviors and pro-environmentalism. These conclusions are consistent with a 2009 study by Nisbet, Zelenski, and Murphy. The 2009 study had a sample size of 831 Canadian undergraduates which intended to measure the correlation between the Big Five and NR and demonstrated that Openness was positively correlated with NR29.

Conscientiousness and Neuroticism are only somewhat associated with CN and pro-environmental behaviors. Although Markowitz et al. found that certain aspects of Conscientiousness (such as diligence and competence) were correlated with pro-environmental action, the ten strongest correlates with pro-environmental action were all facets of Openness28. Diligence had a zero-order correlation of 0.14 and Competence had a zero-order correlation of 0.12 with both having p-values of less than or equal to 0.01, while the lowest “scoring” facet of Openness had a correlation of 0.16 and a p-value less than or equal to 0.001, showing that although Conscientiousness may somewhat correlate with ecological behaviors, Openness displays a stronger and more reliable correlation with ecological behaviors. Additionally, Conscientiousness facets were negatively correlated with pro-environmental action were Conscientiousness facets, therefore showing the inconsistency of the Conscientiousness trait with ecological behaviors. Furthermore, when students self-reported environmental behaviors on the Student Environmental Behavior Scale (SEBS), although Openness showed the strongest relationship to environmental behavior, Conscientiousness also exhibited results of similar positive magnitudes. Therefore, while Conscientiousness can predict pro-environmental action in some cases, it is unreliable, especially when compared to Openness. Neuroticism did not show any relationships with CN in the Markowitz et al. study either. In the undergraduate sample, Neuroticism’s zero-scale correlation with the SEBS was 0.02, with the NEP it was 0.1, and with the CNS it was -0.14. These “scores” are drastically different from Openness zero-score correlations of 0.23, 0.3, and 0.45. In both the adult and undergraduate samples, Neuroticism did not have any significant correlations with CN. Even so, different studies by Milfont and Sibley, and Hirsh that examine the relationship between the two Big Five traits and CN have obtained differing results30,31. While Markowitz et al. found generally weak associations with CN, Milfont and Sibleynoticed a significant association between high environmental concern and Conscientiousness30. Furthermore, while Markowitz et al. did not find any correlation between Neuroticism and pro-environmental behaviors, Milfont and Sibley’s research found that Neuroticism was negatively associated with high levels of environmental value, and Hirsh’s 2010 study discovered a positive relationship between Neuroticism and environmental preservation and concern30,31. As a result, it is presently unclear whether there exists a positive, negative, or no relationship between Neuroticism and environmental behavior. 

Agreeableness and Extraversion are less clearly associated but seem to be somewhat linked to CN, though additional research is necessary to draw a clear relationship. Markowitz et al.’s influential research found no significant correlation between Agreeableness and CN, although the 2007 Hirsh study made opposing discoveries28,32. In the seminal research, not unlike Conscientiousness, some facets of Agreeableness (tender-mindedness and forgiveness) were correlated with EPS. However, the correlations were weak and not sufficient to define an association between the trait and the EPS28. Moreover, both studies in the early seminal research paper did not find any significant correlations between Agreeableness and environmental behaviors due to inconsistent results28. In the same paper, similar to Agreeableness, facets of Extraversion (such as liveliness, activity, social boldness, and positive emotion) appeared to have a positive correlation with the EPS scale. Due to some of the Extraversion facets scoring highly on the EPS scale, the likelihood of performance of pro-environmental behaviors had a weak but consistent correlation with Extraversion, though these results may have been due to a correlation of the Extraversion variable with the Openness variable28. Additionally, when the researchers used an alternate calculation method to further explore the EPS scale results, both Extraversion and Agreeableness showed a slight negative correlation to ecological behaviors. Markowitz et al. convey an unclear relationship between the traits of Extraversion and Agreeableness, and ecological behavior. Other research has discovered conflicting results. For example, studies done in 2007 and 2010 had results that showed a significant positive correlation between Agreeableness and high environmental concern31,32. The 2010 study had a sample size of 2590, with all participants being German residents. The age of the participants ranged from 26-93 years with a mean age of 54.131. This study found that all of the Big Five traits (Openness, Agreeableness, Neuroticism, and Conscientiousness) besides Extraversion had a significant and positive relationship to greater environmental concern. The earlier study done in 2007 made similar conclusions. The study had a smaller sample size of 106 undergraduates from the University of Toronto. The study’s results showed that both Openness and Agreeableness were significantly correlated with environmentalism. Contrary to a common consensus, these results showed that Agreeableness (r=0.33) had a higher correlation coefficient to environmentalism compared to Openness (r=0.24)32. Some researchers speculate that a positive association between Agreeableness and environmental concern may be due to Agreeableness’s relationship to high levels of empathy, which is also often associated with pro-environmental motives (e.g.,concern for others). Like the previous study, Extraversion was not significantly associated with environmentalism. The 2007 and 2010 studies were inconsistent with the findings of Markowitz et. al. Although the researchers of the Markowitz et al. paper found a weak but consistent relationship between Extraversion and environmentalism, the 2007 and 2010 studies found no relationship between the two variables. Conversely, Agreeableness showed slight negative correlations with environmentalism in the seminal research paper, but consistently demonstrated positive relationships to environmentalism in the 2007 and 2010 papers. A multitude of research papers supports the conclusion that as of the time of this writing (2023), a conclusion can not yet be made on the idea of a correlation between Agreeableness/Extraversion, and ecological behaviors, due to the inconsistency of research on the subject. The exact reasons for the inconsistencies and discrepancies are not yet known. Although self-report measures are commonly used in psychedelic research, these types of assessments have inherent biases and can vary across individuals. Nevertheless,  it is encouraging that psychedelics do not simply introduce broad alterations in every personality trait, and are limited to a subset. As opposed to Agreeableness and Extraversion, Openness is a very consistent trait concerning its relationship with pro-environmentalism. This contrast may be due to the strategies used to measure each trait, however this is merely speculatory. For instance, volunteers for psychedelic use studies could potentially exhibit higher baseline associations with agreeableness and extraversion, which may confound the resulting changes and introduce bias. Readers should interpret the reliability of the observed associations as highest for the most consistent traits, and lower for traits that exhibit more variation across research findings.

While all of the Big Five traits have shown at least minimal or weak associations with environmentalism, Openness to experience is the most strongly and consistently associated with environmentalism. All of the other Big Five traits demonstrated varying degrees of association with ecological behaviors. Some studies showed slight negatives associated between the personality traits, others showed positive associations, and some demonstrated no correlation. Therefore, Openness to experience, at the time of this writing (2023), has the most consistent, positive, and reliable relationship with NR, pro-environmentalism, and ecological behaviors.  However, it must be noted that Mayer and Frantz’s CN scale does not have an established standard measure for CN, and therefore may negatively impact the reliability of findings that use their CN scale. Nevertheless, we have reason to believe that Mayer and Frantz’s CN scale displays an acceptable level of reliability due to alpha measures ranging from \alpha =0.74 to 0.8433

Psychedelics and Pro-Environmental Behavior

Many psychedelics have a positive association with pro-environmental behaviors, which may be due to the personality changes the drugs are also affiliated with. This association has received limited study over the past decades, as only 7 studies have published experimental evidence examining this specific relationship. Details about the 7 studies are shown in Table 1. We acknowledge that the reliance on self-reported questionnaires in the 7 studies may introduce a potential bias in the results of the research. However, we believe that in the field of personality research, to a certain extent, self-report bias is unavoidable. This is because it depends on the examination of how subjects see themselves due to psychedelic effects being a wholly subjective experience with limited avenues for objective measurement. Therefore to a certain extent these methodological limitations are unavoidable and are a necessary part of performing personality research. Nevertheless, to minimize the impact of such biases in research, many of the seven studies were made anonymous. This added anonymity is believed to help increase honesty in participant responses, especially when regarding socially taboo topics such as illicit substance use2. Other studies made use of objective knowledge of individuals to measure the association between psychedelic use and pro-environmental behavior34

Table 1: Summary of Primary Research in Psychedelics and Pro-Environmentalism. A collection of primary research obtained using the search engine Google Scholar found only seven total papers which directly address and discuss the relationship between psychedelics and pro-environmentalism. The locations of all the papers were not available due to 2/7 of the research being done in the form of anonymous questionnaires. Sample size of the collection of research varies widely with a minimum of 7 participants with a maximum of 1487 participants. 6/7 of the papers used self-reported questionnaires to collect data. Majority (4/7) of the papers were published in the year 2022 and cited by less than 10 people.

Some of the personality traits that are associated with psychedelic use such as Openness to experience and ego-dissolution are also associated with pro-environmentalism, ecological behaviors, and NR. One study which examined the relationship between overall psychedelic use and NR affirmed that psychedelics have a positive correlation to NR, and further demonstrated that the extent of increase in NR was dependent on the intensity of ego-dissolution during the psychedelic sessions/experiences35. Therefore, psychedelics’ association with ego-dissolution likely allows them to correlate with pro-environmental behaviors and NR. Due to the positive association demonstrated from psychedelics to ego-dissolution to NR, we speculate that ego-dissolution is positively aligned with one’s likelihood to engage in pro-environmental actions. Similar relationships involving Openness to experience in replacement of ego-dissolution can be found in further studies. For instance, using a sample size of 2690 adults, Hirsh (2010) examined the relationship between personality and environmental concern, finding that Openness is related to higher levels of environmental concern. Moreover, regarding overall psychedelic use, a large-scale population study composed of 1487 participants demonstrates classic psychedelics’ contribution to users’ pro-environmental behavior2. The study used substances such as cannabis and ketamine to compare their experiences with psychedelics in the experiment. The researchers concluded there existed a positive relationship between lifetime experience with classic psychedelics and two sub-dimensions of NR (NR-Self and NR-Experience)2. They also stated that as experience with classic psychedelics increased, so did enjoyment in nature and likelihood of construing oneself with nature2.  

Psilocybin is strongly linked to the personality trait of Openness to experience. In the past, Openness has shown consistent and significant positive associations with ecological and pro-environmental behaviors. Therefore, due to Openness’ association with both psilocybin and pro-environmentalism, it is not unreasonable to conclude that psilocybin use may also have a positive relationship with ecological behaviors. Indeed, past research has shown such correlations. For instance, in a clinical study investigating the effects of psilocybin on patients with TRD, researchers found that after administering psilocybin in two doses, NR significantly increased3. The experiment included 7 patients with moderate-severe TRD, and 7 healthy control subjects. There were two administration sessions, one week in between, in doses of 10 mg and 25 mg respectively. After the first session, the patients’ nature relatedness significantly increased. Additionally, NR remained significantly increased even 7-12 months after the dosings3. The clinical study not only demonstrated psilocybin’s strong association with NR but also showed the durability of the relationship. Due to the study’s small sample, the results of the experiment should be interpreted with caution, however, because psilocybin demonstrated temporal consistency in effects such as decreasing tobacco dependency, end-of-life anxiety, and lessening symptoms of TRD, we believe that it is reasonable to believe that psilocybin may demonstrate a similar consistency with increases in NR, despite the absence of longitudinal studies of psilocybin and NR13,14,15. Nevertheless, there are additional studies that demonstrate psilocybin’s relationship with NR and pro-environmental behaviors. A meta-analysis by Forstmann et al. which aimed to determine which psychedelic had the greatest predictive ability of NR discovered that psilocybin was the strongest predictor of NR36. The meta-analysis consisted of 5 different studies and analyzed the psychedelics psilocybin, LSD, mescaline, Salvia divinorum, ketamine, and ibogaine. After analyzing the 5 studies, psilocybin was shown to have one of the strongest associations between past use, and nature-relatedness in participants who were both experienced and inexperienced with psychedelics. However, when analyzing only the studies where participants were experienced psychedelic users, only psilocybin use positively predicted NR.  

LSD has shown similar results to psilocybin regarding association with pro-environmental behaviors. Psilocybin use is associated with Openness, and likewise, a study found that after participants were given doses of LSD, their levels of Openness to experience increase significantly21. Since Openness is consistently correlated with NR and ecological behaviors, it may be predicted that due to LSD’s relationship with Openness, the psychedelic is a predictor of pro-environmentalism. Some studies have demonstrated this relationship. For instance, a 2022 study by Sagiglou and Forstmann utilized an online questionnaire to examine relationships between NR, concerns about climate change, and objective knowledge about climate change across 651 participants of a variety of nationalities and past drug experiences. The researchers discovered that out of 30 different substances, experience with LSD was one of the most positively associated with NR. Additionally, LSD was one of only two drugs with any correlation to the likelihood of climate change knowledge34. However, much like the other substances, LSD use did not show any significant correlation to concern about climate change. A study done in Brazil further demonstrated LSD’s relationship to NR. The research aimed to learn how 7 different substances (ayahuasca, psilocybin, LSD, MDMA, etc.) correlated to NR levels. The results showed that those who had no prior experience with LSD had significantly lower NR scores compared to both past and current users of the drug. However, past and current users of LSD had no significant difference in scores9. Furthermore, when using regression models to compare relationships between naive, past, and current users of the seven drugs and NR-6 scores, LSD was one out of three drugs that showed significantly higher scores with past (and current) use compared to naivety9.

While ayahuasca has inconsistent relationships with Openness to experience, there is speculation that due to the drug’s high association with “self-transcendence” (which is a positive predictor for NR and environmental concern), ayahuasca may also have positive relations with NR and pro-environmentalism. Although few studies investigate this “ayahuasca/NR” theory, there are some studies that explore the concept. For instance, a study that observes the effects of a variety of drugs on NR found many examples of ayahuasca’s relationship to NR. When comparing past/current users of ayahuasca to naive individuals, there was a significant difference in NR-6 scores, where past/current users had significantly higher scores compared to the naive participants. However, there was no significant difference between past users and current users. Nevertheless, in the study’s regression models, current users of ayahuasca showed significantly higher NR-6 scores compared to past users and had a positive association with NR9. Furthermore, those who declared lifetime use of ayahuasca showed higher scores than both current and past users9. While the previous study explored a variety of drugs’ correlation with NR, there also exists a pilot study that focuses specifically on ayahuasca and NR37. The results of the study should be taken with reservations due to the lack of clarity involved in the study; researchers are unsure that ayahuasca was the only factor contributing to a change in NR in participants. The study consists of 58 participants, all of whom were involved in ayahuasca retreats of varying lengths37. Participants answered questionnaires before and after the retreat. Results of data analysis showed a positive relationship between participation in the ayahuasca retreat and NR. However, the specific cause of the relationship has not been determined and therefore must be explored further. 

Psilocybin, LSD, and ayahuasca all demonstrate a relationship with NR and pro-environmentalism. However, the consistency and degree of confidence in the relationships vary among the drugs. Psilocybin has exhibited the most reliable positive relationship with NR and pro-environmentalism, therefore making it the most reliable predictor of the two traits. Some research has even revealed that the effects of NR after psilocybin administration are long-standing, and may last up to 12 months. LSD also seems to consistently associated with NR. Additionally, LSD seems to outperform some other drugs when it comes to NR and pro-environmentalism. Lastly, although not strongly associated with Openness, ayahuasca appears to have a possible association with NR and pro-environmentalism. However, due to a lack of research concerning ayahuasca’s relationship with NR, there is low confidence in studies that found a positive relationship between the drug and NR.  We understand that the limited availability of research concerning the specific relationship between psychedelics and pro-environmentalism raises concerns about the validity of our research. We would like to emphasize the nature of the current study and highlight that we do not attempt to make significant conclusions regarding the benefits of psychedelic use on pro-environmental behavior. Rather, we critically examine existing studies that have begun to explore this complex and multifaceted topic. Although psychedelics are a diverse class of psychotropic substances, they act on overlapping serotonergic pathways and promote specific changes in personality that converge on similar traits. Given these broad similarities, it is valid to generalize the effects of these substances on pro-environmental behaviors. 

Discussion

While the present review is meant to focus largely on pro-environmental behaviors, NR is often used interchangeably with pro-environmentalism as the two terms are strongly associated with each other. Many studies including one by Liu et al. have already established their relationship, showing that there exists a positive relationship between the two measures26. Past research by Forstmann and Sagioglou involving psychedelics and pro-environmentalism have utilized NR as a bridge between the two topics of research2. Therefore, when discussing the drugs’ relationship with pro-environmentalism, displaying a positive association with NR can be interpreted as a positive association with pro-environmentalism as well.  

 Unlike topics that involve associations between psychedelics and subjects such as depression, anxiety, crime, or post-traumatic stress disorder (PTSD), the relationship between psychedelic use and pro-environmentalism/NR has not been as well established. As seen in Figure 1, while topics such as “Psychedelics and Anxiety” or “Psychedelics and Depression” reach citation counts beyond 10,000 by the year 2020, “Psychedelics and Nature Relatedness” does not even reach 5000 by that time. This contrast in popularity may be due to psychedelics’ direct engagement with regions of the brain that control and influence mood regulation. Therefore, there is a more obvious connection between psychedelics and mental health. By contrast, pro-environmentalism and NR are not clearly associated with specific regions of the brain that psychedelics interact with. As a result, there is a less obvious association between pro-environmentalism and NR. Additionally, research involving mental health may be more prevalent compared to NR because scientists are aware of the apparent consequences of their research. The ability to lessen symptoms of illnesses such as depression or anxiety has high appeal, especially as rates of mental illness increase. On the contrary, increasing users’ level of pro-environmentalism has less apparent positive effects. However, as the climate crisis becomes more apparent, the necessity for NR is evident. 

The climate crisis has been an object of concern for many decades since the time of this writing (2023). For instance, the United Nations has shown public concern with environmental conservation since 197238. However, there are still people who are reluctant to contribute to the climate movement. Whether the reluctance is due to denial of the climate crisis or general unwillingness to make meaningful changes, as temperatures are rising there is a necessity for a driver of change. Due to NR’s association with positive ecological behaviors and ecological pro-activeness, inducing increased measures of NR in citizens has potential as a plausible step towards environment conservation. By understanding different NR relationships with personality traits, interventions or strategies aimed at developing a greater connection between humans and nature may be able to target an expression in certain personality traits that demonstrate positive associations with NR to help increase the efficacy of the interventions.  Furthermore, psychedelics could be used to help increase NR. If psychedelics are administered to aid in the increase of NR, which then increases ecological behavior, people may be more inclined to help combat the climate crisis. However, at the time of this writing (2023), this “psychedelic-NR” solution is not probably due to the lack of research on the topic. Therefore, researchers and scientists must continue to contribute to this field to help increase awareness and knowledge regarding psychedelics’ relationship to NR. 

An additional potential consequence of using psychedelics to help increase NR is an improvement in certain aspects of mental health. Not only is NR a strong indicator of positive ecological behaviors, but NR is associated with better mental health and overall life satisfaction. Specifically, NR has displayed positive relationships with greater feelings of happiness and worthiness7. Additionally, psychedelics have a long-established connection with improving mental health. By using psychedelics to combat the climate crisis, many users may experience a reduction of symptoms of illnesses such as depression or anxiety. Improvement of mental health is important in the context of environmentalism because the effects of the climate crisis are not limited to their obvious impacts on food availability, uninhabitable temperatures, and societal displacement. They can extend to the mental health crisis sweeping modern society. For instance, feelings of hopelessness, despair, and inability to make a change are common mental issues driven by an overarching concern for global warming39. Additionally, because the rate of natural disasters such as hurricanes, tsunamis, etc. have increased due to climate change, more and more victims of such events have experienced serious mental decline and effects such as PTSD, MDD, anxiety, and more40. However, given the perspective on psychedelic use as a potential therapy for mental health, we should consider how these effects can come into play while also aiding in the climate conflict. Not only can psychedelics help improve mental health, but they may have the potential to improve the health of our environment. 

Conclusion

Certain psychedelics such as psilocybin, LSD, and ayahuasca have shown positive correlations with pro-environmentalism and NR. Psilocybin, notable for its potential as a treatment for certain mental illnesses such as TRD and end-of-life anxiety, appears to have a strong relationship with Openness to experience. Past studies by Markowitz et al. and Nisbet et al. have demonstrated Openness to experience’s strong connected to pro-environmentalism. Therefore, by using Openness to link psilocybin and pro-environmentalism, it may be concluded that there is a feasible positive relationship between the psychedelic and pro-environmentalism. The connection between LSD and NR may also be explained by these circumstances. LSD is a psychedelic well known for its positive effects on improving alcohol-use disorder and treating MDD. LSD looks to be associated with Openness. Therefore, by the same system of patterns, it is implied that LSD shares a positive relationship with NR. Conversely, ayahuasca has a hesitant relationship with both Openness and pro-environmentalism/NR. Ayahuasca has historically been used in rituals. After administration, users have reported feelings of unity and connection with peers. Although there is not much evidence at the time of this writing (2023) to strongly support a relationship between ayahuasca and Openness, ayahuasca does seem to be associated with self-transcendence. There also exists a link between self-transcendence and NR. Therefore, ayahuasca’s slight association with NR can be explained by the relationships between ayahuasca, self-transcendence, and NR. There is much to be learned about the association between psychedelics and NR/pro-environmentalism. For instance, at the time of this writing (2023), scientists lack a deep understanding of the mechanisms driving these associations and the limits and extents of these associations. Continuous research and activity in this research field could lead to many desirable consequences such as improvements in both our physical and mental world. Research in this field of study must increase, so that our understanding of these ecological effects continues to aid us in the future.

Methods

In the current research, I perform a literature review and collect data from a variety of existing studies, articles, and journals. I gathered a collection of papers and published experiments relevant to my research by using online resources and search engines such as Google Scholar. Some keywords I used in my search include “The Big Five and psilocybin”, “ayahuasca and NR”, and “The Big Five and pro-environmentalism”. I then extracted information and interpreted data from relevant papers to help answer my research question from many different angles. For example, I looked at certain personality traits that psychedelics may induce upon use, and how those personality traits affect a user’s pro-environmentalism. I will answer my research question and draw a conclusion on my research topic based on the interpretation and analyses of the data I collected. Lastly, I acknowledge the research gaps found in this field.

Acknowledgments

I would like to recognize Lumiere Education for granting me this unique opportunity. I am also deeply grateful to David Nikom for his generous guidance and mentorship during the research and writing process. Finally, I extend my gratitude to Rose Wang for her valuable assistance during the writing process.

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