OPEN Foundation

OPEN Foundation

Effects of Long-Term Ayahuasca Administration on Memory and Anxiety in Rats

Abstract

Ayahuasca is a hallucinogenic beverage that combines the action of the 5-HT2A/2C agonist N,N-dimethyltryptamine (DMT) from Psychotria viridis with the monoamine oxidase inhibitors (MAOIs) induced by beta-carbonyls from Banisteriopsis caapi. Previous investigations have highlighted the involvement of ayahuasca with the activation of brain regions known to be involved with episodic memory, contextual associations and emotional processing after ayahuasca ingestion. Moreover long term users show better performance in neuropsychological tests when tested in off-drug condition. This study evaluated the effects of long-term administration of ayahuasca on Morris water maze (MWM), fear conditioning and elevated plus maze (EPM) performance in rats. Behavior tests started 48h after the end of treatment. Freeze-dried ayahuasca doses of 120, 240 and 480 mg/kg were used, with water as the control. Long-term administration consisted of a daily oral dose for 30 days by gavage. The behavioral data indicated that long-term ayahuasca administration did not affect the performance of animals in MWM and EPM tasks. However the dose of 120 mg/kg increased the contextual conditioned fear response for both background and foreground fear conditioning. The tone conditioned response was not affected after long-term administration. In addition, the increase in the contextual fear response was maintained during the repeated sessions several weeks after training. Taken together, these data showed that long-term ayahuasca administration in rats can interfere with the contextual association of emotional events, which is in agreement with the fact that the beverage activates brain areas related to these processes.

Favaro, V. M., Yonamine, M., Soares, J. C. K., & Oliveira, M. G. M. (2015). Effects of Long-Term Ayahuasca Administration on Memory and Anxiety in Rats. PloS one, 10(12), e0145840. http://dx.doi.org/10.1371/journal.pone.0145840
Link to full text

Neuroimaging in moderate MDMA use: A systematic review

Abstract

MDMA (“ecstasy”) is widely used as a recreational drug, although there has been some debate about its neurotoxic effects in humans. However, most studies have investigated subjects with heavy use patterns, and the effects of transient MDMA use are unclear. In this review, we therefore focus on subjects with moderate use patterns, in order to assess the evidence for harmful effects. We searched for studies applying neuroimaging techniques in man. Studies were included if they provided at least one group with an average of <50 lifetime episodes of ecstasy use or an average lifetime consumption of <100 ecstasy tablets. All studies published before July 2015 were included. Of the 250 studies identified in the database search, 19 were included.

There is no convincing evidence that moderate MDMA use is associated with structural or functional brain alterations in neuroimaging measures. The lack of significant results was associated with high methodological heterogeneity in terms of dosages and co-consumption of other drugs, low quality of studies and small sample sizes.

Mueller, F., Lenz, C., Steiner, M., Dolder, P. C., Walter, M., Lang, U. E., … & Borgwardt, S. (2016). Neuroimaging in moderate MDMA use: A systematic review. Neuroscience & Biobehavioral Reviews, 62, 21-34. http://dx.doi.org/10.1016/j.neubiorev.2015.12.010
Link to full text

[Interview] Bill Richards: “The ideal treatment includes some kind of mystical transcendence”

Richards_BillBill (William A.) Richards is a clinical psychologist in the Psychiatry Department at the Johns Hopkins School of Medicine, where he has pursued research with psychedelics during the past sixteen years, including his current studies on psilocybin-assisted psychotherapy with cancer patients coping with end-of-life issues. Richards’ psychedelic research stems back to 1963; he worked with colleagues such as Walter Pahnke and Stanislav Grof in the late 1960’s and early 1970s. More recently, he details his decades of scientific scholarship on psychedelics and human consciousness in his book, “Sacred Knowledge: Psychedelics and Religious Experiences.” OPEN Foundation talked to Richards, who is immediately affable and speaks about his work with both serious and tangible enthusiasm. [fusion_builder_container hundred_percent=”yes” overflow=”visible”][fusion_builder_row][fusion_builder_column type=”1_1″ background_position=”left top” background_color=”” border_size=”” border_color=”” border_style=”solid” spacing=”yes” background_image=”” background_repeat=”no-repeat” padding=”” margin_top=”0px” margin_bottom=”0px” class=”” id=”” animation_type=”” animation_speed=”0.3″ animation_direction=”left” hide_on_mobile=”no” center_content=”no” min_height=”none”][Bill Richards will be among the speakers at our ICPR 2016 conference on psychedelics research.]

You’re a clinical psychologist with formal training in theology and comparative religion and have spent your entire career investigating the promise of psychedelics in clinical treatment. How did all these disparate strains of interest come together?

When I first arrived in college, I thought I would be a minister and majored in Philosophy and minored in Psychology and Sociology. Then I went to Yale Divinity School, where I studied courses such as contemporary Hindu systems and language analysis, and my vision of religion grew increasingly rich and broad. But at the end of the first year, I wasn’t sure it was right for me.

Then I studied in Germany (at the University of Göttingen) where I accidentally stumbled on psychedelics in 1963. While I found some of the theological courses there rather pedantic—sometimes arguing over the meaning of certain Hebrew words—to my surprise, I discovered the experiential dimension of religion in the School of Medicine, where different alternative states of consciousness were taken seriously, including experiences of a religious nature often viewed as revelatory.

After Yale, I went to Andover Newton Theological School and studied the Psychology of Religion, followed by courses at Brandeis University with the Humanistic/Transpersonal psychologist, Abraham Maslow. Then I was offered a job working with psychedelics and moved from Boston to Baltimore (where I pursued psychotherapy research with LSD, DPT, MDA and psilocybin at the Maryland Psychiatric Research Center). But I felt I didn’t have the right letters after my name to qualify as a researcher so I continued my studies at Catholic University, got a PhD and became a licensed clinical psychologist.

When I went through graduate school some people seemed to look at me as if I was aimless—I studied music, philosophy, psychology and religion—but looking back, I see it was the perfect training for the work I do. I became a psychedelic therapist long before the name was even invented and somehow, I intuitively seemed to know what I was doing!

What did you initially work on in the early days?

When I arrived in Baltimore we had two federal grants from the National Institute of Mental Health to pursue research with LSD-assisted psychotherapy: one for treating alcoholics and the other for treating what we labelled “neurotics” at the time, hospitalised people who were depressed, anxious or suffering with personality disorders. I also began working with cancer patients struggling with anxiety and depression (which had minimal funding). One of the reasons I was hired was my theological background.

From working with such disparate groups, I’ve learned that people are people no matter what their diagnosis. Everyone experiences grief, guilt and anger, high points and low ones, and yearns for a philosophy or understanding that helps life make sense.

Could you please guide me through how you work with someone in a clinical setting?

The basic format for a session with a psychedelic substance is that there are two therapists present; one is the primary and the other is the co-therapist. We treat one person at a time, which allows each volunteer to have an interior focus. The subject lies on a couch; we use eyeshades and headphones to help them relax but also, to help them dive deeply into the mind. This produces a safe and productive way to work, as the subject doesn’t get distracted by sensory perceptions of what’s in the room, or any pressures to be social and interact. Typically, people experience more profound content when an initial psychedelic session is structured in this manner than they might otherwise in a different setting. In terms of measuring the variables, it’s also easier to work with one person at a time. If several subjects were in the room, simultaneously having psychedelic experiences, it would complicate the research design.

I read an article in the New Yorker mentioning how you created a set of “flight instructions” for those undergoing psychedelic therapy. At what point did you create this and why?

It’s not something I ever wrote down as a formal document; it’s more like an informal checklist shared with the subject in person. It helps to cement the relationship and promotes a sense of security. It covers practicalities from how we handle someone going to bathroom or what to do if they feel the need to vomit, to how to navigate within their field of consciousness. For example, if something threatening appears, we encourage subjects to reach out for support if they need it, and to look the threatening image in the eye. In other words, to go towards it because when people seek control by trying to avoid what’s there, that’s when they become paranoid and confused. Resistance usually comes from fighting what’s happening. Telling them to “Trust, Let go, and Be open” is our basic mantra. We also encourage them to send their intellects outside to play in the yard during the period of drug action, rather than trying to cognitively categorise the experience when it is occurring.

Many researchers posit that the power of suggestion may play a role when medical professionals administer psilocybin. Is it true that under such conditions, the patient will be more likely to fulfil the therapist’s expectations (including avoiding a bad trip)?

It’s critical that people feel safe. We suggest that people declare “Open House” in their minds, affirming that everyone and everything is welcome. I’d say the content of an interior journey is rarely influenced by suggestion, though, because people have radically different experiences in identical settings. In very low doses, psychological suggestion may play a stronger role in terms of imagery but in medium and high doses, the content seems independent of what one might expect and often quite surprising.

It’s often a struggle for people to coordinate their language and ideas with their actual experiences on psychedelics. For example, I recently worked with an atheist who had a profound spiritual experience and subsequently claimed to have “seen God”. Then there are those who yearn to experience a beatific vision of Christ, like some priests, but instead find themselves dealing with childhood issues, such as being molested. Psychedelics reliably seem to take you right to where the work needs to be done.

This unpredictability is why some people fear psychedelics, labelling them as dangerous. But for the individual undergoing the unfolding process, there’s an incredible wisdom and choreography to all of it that makes sense. In other words, what happens isn’t chaotic or by chance—it all has meaning.

You refer to psychedelics as ‘entheogens,’ which literally means a compound that “generates the divine within,” and your work is focused on mystical/religious experience and its benefits. Many religious scholars have wondered if chemically induced mystical experiences are the same as naturally occurring ones. What do you think?

There may well be a chemical substrate to everything we experience. For example, we know that DMT is naturally produced in humans. One hypothesis is that when someone deep in meditation experiences a spiritual moment, more DMT is generated, or perhaps the balance of CO2 to O2 in the blood changes, or whatever. But there’s probably always a chemical substrate that correlates with whatever we experience, with and without psychedelic substances.

I have no idea if saints throughout history ate psychogenic mushrooms in their stew or if they had mystical experiences simply due to the makeup of their natural biochemistry.

What is a gift of grace and what is induced by what we eat? Who knows? But there is no doubt that incredibly profound mystical experiences sometimes happen when one ingests psychedelics in adequate dosage in a supportive environment with serious intentions. They are wonderful tools because they are so reliably potent in helping people actually experience deep, transformative states of human consciousness. Phenomenologically, the content of transcendental psychedelic sessions (retrospectively described) appears indistinguishable from the content reported in the historical literature of mysticism, so it is probable that they indeed reflect the same quality and depth of experiencing.

You employ scientific methods to explore psychedelic experiences, or states of consciousness that often are highly individual and ineffable. Is it really possible for science to explore mystical experiences?

The science is the design of the research project. Let’s say one person gets Ritalin and the other psilocybin with the same expectation in a “double-blind” design; the only thing different is the content of the capsule, which no one knows except for the pharmacist. Science thereby establishes that, yes, it really is psilocybin that triggers profound experiences, not just suggestion because those who were administered Ritalin did not report the same experiences.[1]

I am now conducting a psychedelic study with leaders from different world religions. There’s a waiting list control group, so following screening and acceptance some are randomly assigned to immediate preparation for psilocybin while others have to wait 6 months before they enter the active phase of the study. We’re comparing what happens to those who haven’t taken psilocybin with those who have and collecting this information through questionnaires, and formal interviews with family and colleagues. We’re especially interested in studying changes in attitudes and behaviour that tend to be reported after transcendental states of consciousness have been experienced. The state of consciousness we call “mystical”, characterised by reports of unity, transcendence of time and space, intuitive knowledge, sacredness, deeply-felt positive mood and ineffability, appears not only to be awesomely meaningful for those who experience and remember it, but it also appears to facilitate what William James called “fruits for life.”

Why it is important to explore such states?

Some people just live their lives, never worrying about where we came from, where we’re going and why we’re on this little planet spinning through space. Others do. Maybe it’s a gene. Some of us have a religious or philosophical gene that wants to understand what life means. I think most people ask these questions when life gets difficult, when they’re forced to approach death (their own or a loved one’s) or even when they see the birth of a child. It’s that sense of mystery.

I like to think that, as part of our current evolution within consciousness, we are beginning to understand that we are still being created and waking up. I think the current focus on meditation, spiritual development, yoga and beyond in our culture reflects a yearning to awaken to broader consciousness. I believe mystical consciousness is simply intrinsic to our being.

Research has proven that psychedelics facilitate the occurrence of mystical forms of consciousness in healthy volunteers with a high degree of reliability. Would you then say that mystical experience is a key factor in the benefits subjects derive from psychedelic treatment?

Yes. If there could be only one key factor that would be it. Experiencing a sense of unified consciousness is life-transforming for many people. In that sense, we are not really studying the effect of psilocybin as a simple drug effect so much as we’re studying the effects of discrete alternative states of human consciousness.

The most dramatic shifts in attitudes and behaviour seem to happen in the aftermath of a mystical experience. We see changes in a person’s concept of what the nature of reality is, who they are, their connection to others; it gives them a sense of confidence that there is nothing within that cannot be forgiven and resolved; there’s an increase in self worth; an appreciation of beauty and treasuring others, even those one disagrees with. The ideal treatment appears to be one that includes both experiences of psychodynamic resolution and some kind of mystical transcendence.

Does having a psychedelic experience challenge the prevailing materialistic paradigm?

I would rather say it enriches or deepens it. Philosophically, I think the question that arises is “What is the ultimate nature of matter?” When we look at matter from the viewpoint of quantum physics, we’re just beginning to understand there are deeper substrates to the so-called “material world”.

It has been reported consistently in psychedelic research that mystical experiences, when they occur, have a powerful effect in removing the fear of death; there’s something about these states that feels more real than everyday reality. This brings up the classic mind/body problem: what is the relationship of the brain to consciousness? If, as some theorise, the brain receives and processes consciousness like a radio would a radio signal, where does consciousness actually originate? Another example: if you dissect a television set, you cannot find a trace of the blonde newscaster who just delivered the news inside of it. But the broadcast did happen—it came from somewhere. We’re at the edge of a fascinating frontier, in psychiatry, in religious studies and in physics. Ultimately, we honestly still do not know what we are.

Many first-wave studies have been criticised as being flawed in more than one way, and sometimes even unethical. Was this simply how science was done at the time, or did the ‘wild enthusiasm’ for this novel range of substances play a part in the sometimes reckless way in which experiments were conducted? Historically, it led to popular hysteria and ultimately restrictive legislation, which have taken decades to recover from.

There was a lot of early enthusiasm. When psychedelics first appeared in modern Western culture, they were just sent through the mail to therapists. Timothy Leary wasn’t the only one working with these substances. A lot of people were using them clinically at universities or in private practices, both in Europe and North America to experiment with their usefulness. While some clinicians weren’t trained as researchers and there were no control groups, many carried out studies with great responsibility and care. Psychedelics actually have a remarkable safety record. Indigenous groups have used these chemicals in their plant-based forms (ayahuasca, psilocybin-containing mushrooms, peyote, etc.) in group formats for thousands of years without anyone ever checking their blood pressure.

In the 1960’s we weren’t prepared to deal with psychedelics and many people clumsily misused them. The media reaction was alarmist and psychedelics were quickly devalued. The press is much saner now, approaching psychedelics from a much more sober, grounded perspective.

Why is that? Our research designs are much tighter today. We have gathered decades more of testimonials and statistics about how extraordinary these drugs are. The entire field has matured—we know more. We’re smarter. We’ve learned that psychedelics are not for everyone. There are a multitude of ways to explore personal and spiritual growth, so even if they one day become legally available, I don’t think everyone will be interested in using them. In fact, some people should be wisely counselled not to, such as those with some severe forms of mental illness.

Suppose that you had all means of scientific investigation ready to use, which question would you like to have answered?

In my book there are three chapters that address such questions—one on medical, one on educational and one on religious frontiers—and I could go down any of those paths. Medically, the promise of psychedelics in treating addictions appears to be very hopeful. Outside medical treatment, they may well hold great promise in facilitating creativity and perhaps that’s what I’d explore.

 One problem is that people who generally shouldn’t be taking psychedelics—such as young people, who do it recreationally—are taking them whereas responsible, established scholars aren’t. So what we frequently see in the press are stories on how young people are ending up in emergency rooms, rather than hearing about how scientists are discovering new insights through the use of psilocybin, DMT, mescaline or LSD. Steve Jobs once claimed that psychedelics gave him critical intuitive insights that enhanced his creativity in life. I would love to give well-trained physicists on the frontier of their discipline a structured psychedelic experience. There could be really valuable new insights and perspectives from such a study.

I also have a wild fantasy that some day it will be an option (for those in religious studies) to have a psychedelic experience with academic credit. Whether they are studying to become a Christian minister, Jewish rabbi, Hindu or Buddhist priest or Islamic imam, I propose that having a profound religious experience could be a part of their training, rather than relying on scriptures and traditions alone.

Do you have any plans for future psychedelic studies you would like to carry out?

I would love to see work done exploring the value of psychedelics with sociopathic personalities. The way we fill prisons today is not enlightened. There are ways of helping those with traumatised childhoods to gain a sense of personal value and respect for other people, and to develop a sense of ethics that is genuine and not imposed, but instead rises from within. It wouldn’t be cheap and it would require intensive therapy, but compared to locking someone up for life, it would still make good sense economically, as well as altruistically. Especially for young people just beginning to tumble into the prison system, such treatment just might change the course of their lives.

[1] see csp.org/psilocybin for published research studies and commentaries

[/fusion_builder_column][/fusion_builder_row][/fusion_builder_container]

The OPEN Foundation in Vrij Nederland magazine

Vrij NederlandIn an article about the relentless rise of psychedelic research, the latest issue of Vrij Nederland magazine (December 12, 2015) extensively mentions The OPEN Foundation. In her article entitled “Tripping on prescription”, journalist Freke Vuijst sets off with some quotes from a cancer patient who was able to kick her end-of-life anxiety altogether by participating in the New York University psilocybin study. Having brushed the main aspects of the NYU study and its amazing successes, the author goes on to sketch the history of the first wave of psychedelic research and the subsequent ban on LSD and other substances. Joost Breeksema, chairman of The OPEN Foundation assesses the negative impact Jan Bastiaans’ therapeutic work in the Netherlands and the justified criticism it elicited.

The article then switches back to the present and near future, where phase-3 trials are underway for MDMA/PTSD and psilocybin/end-of-life anxiety. Absent public funding and research investments from the pharmaceutical industry, the difference between the United States and Europe is marked. Whereas the US have an important private charity tradition and large research universities, Europe and the Netherlands are used to rely on public funding, which means research is rather scarce, despite the obvious rise in public interest.

De serotoninewaan

serotonin picNet zoals de Heilige Graal in de Arthuriaanse literatuur welzijn, oneindige rijkdom en een overvloed aan voedsel symboliseerde, is tegenwoordig de beruchte neurotransmitter serotonine gekoppeld aan stemming, aandacht, honger, etc. (Young & Leyton, 2002; Wingen, et al., 2008; Feijó, et al., 2011). Het zou echter kunnen dat serotonine teveel status krijgt toegeschreven. Net zoals Harmon (2009) het effect van serotonine op het zwermproces van sprinkhanen heeft beschreven, lijkt het ’t zelfde effect te hebben op neurowetenschappers (Harmon, 2009).

Serotonine is een van de drie monoamine neurotransmitters, samen met dopamine en norepinefrine (Kolb & I.Q., 2003). De serotoninereceptor heeft zeven grote subfamilies, meer dan de andere twee monoamines, en heeft zelfs nog meer subtypes. Serotonine is inderdaad een cruciale neurotransmitter, maar het is belangrijk om op te merken dat het slechts een modulator is van andere neurotransmitters. Serotonine regelt de werking van glutamaat en GABA, de belangrijkste neurotransmitters, en beheerst de prikkelende en remmende signalen in het brein. De uitzondering is 5HT3, dat de stroming van ionen beheerst (Ciranna, 2006). Om de functie van een multifunctionele neuromodulatorische transmitter goed te begrijpen is het nodig om een beter begrip te krijgen van de stroomafwaarts gelegen secundaire hersenbanen om de belangrijke opeenvolgende biochemische stappen duidelijk te maken. Serotonine is niet de ultieme wonderstof inzake psychiatrie zoals penicilline dat was voor gramnegatieve bacteriën. Misschien is het slechts een van de factoren die tot inzicht kunnen bijdragen.

Serotonine heeft zijn faam binnen de wereld van de geestelijke gezondheid grotendeels te danken aan ontdekkingen die dankzij LSD werden gedaan. Slechts vier jaar na Hofmann’s beroemde ontdekking werd LSD gebruikt om experimentele psychoses te veroorzaken (Miller, 2014). Bijna een decennium later leidde de opmerkelijke gelijkenis tussen de structuren van LSD en van serotonine tot de ontdekking van serotonine in de hersenen. Op basis daarvan begon de wetenschappelijke wereld met het ontrafelen van de relatie tussen de chemie van het brein en het gedrag dat hieruit voorkomt (Miller, 2014). Er zijn nu, meer dan 70 jaar later, meer dan een miljoen papers met ‘serotonine’ in de titel.

Dit doet denken aan de tijd toen het menselijke genoom voor het eerst volledig in kaart werd gebracht, en de wetenschappelijke wereld enthousiast bezig was om ieder defect gen te vinden dat aan de basis lag van iedere denkbare ziekte. Vandaag de dag is de neurowetenschappelijke wereld zich gaan blindstaren op de rol van een simpele molecule in een groot scala aan complexe mentale stoornissen. Maar tegenwoordig begrijpen we dat stoornissen polygeen zijn, en het resultaat afhankelijk is van verschillende variabelen, zoals proteïneproductie, compenserende mechanismen en invloeden uit de omgeving (Bethesda, 1998). Serotonine zou een significante rol kunnen spelen bij geestesziekten, maar een aantal andere factoren hebben waarschijnlijk ook invloed op de wijze waarop ziekte zich manifesteert. Het model van schizofrenie-achtige psychose zoals die wordt opgewekt door phencyclidine (PCP) en ketamine laat zien dat glutamaatreceptoren en dopamine ook een centrale rol kunnen spelen in de mentale gezondheid (Javitt, 2007). Hoezeer de chauffeur ook een sleutelrol speelt in het besturen van een auto, sommige onderzoekers hebben nog niet ingezien hoe belangrijk de brandstof, motor, gekozen weg en andere op het eerste gezicht onbelangrijke variabelen zijn.

Thomas Ray wijdt uitgebreid uit over de diverse manieren waarop psychedelica functioneren. In zijn paper “Psychedelics and the Human Receptorome” illustreert hij de veelzijdige interacties die psychedelica hebben met verschillende receptoren (Ray, 2010). In samenwerking met het National Institute of Mental Health-Psychoactive Drug Screening Program (NIMH-PDSP) heeft hij de receptoraffiniteit en -promiscuïteit van 35 psychedelische drugs gepresenteerd. De resultaten laten zien dat deze 35 drugs niet selectief inwerken op een enkele receptor, maar wel op een grote verscheidenheid aan verschillende types tegelijkertijd. Zelfs stoffen met bijna identieke moleculaire structuren hebben zeer uiteenlopende mechanismen (zie figuur 1 voor een vergelijking tussen DOB en DOI).

[fusion_builder_container hundred_percent=”yes” overflow=”visible”][fusion_builder_row][fusion_builder_column type=”1_1″ background_position=”left top” background_color=”” border_size=”” border_color=”” border_style=”solid” spacing=”yes” background_image=”” background_repeat=”no-repeat” padding=”” margin_top=”0px” margin_bottom=”0px” class=”” id=”” animation_type=”” animation_speed=”0.3″ animation_direction=”left” hide_on_mobile=”no” center_content=”no” min_height=”none”]

ray receptorome
Figuur 1: Ray (2010)

De hoogste affiniteit van bijvoorbeeld DOB is voor 5HT2B, 5HT2A en 5HTC, en in mindere mate voor 21 andere receptoren. Voor DOI geldt dat de affiniteit het hoogste is voor 5HTC en twee andere niet-serotonerge receptoren, en 23 andere receptoren worden ook beïnvloed (Ray, 2010). Het is nog verrassender dat voor veel populaire hallucinogenen en empathogenen de hoogste affiniteit niet noodzakelijk voor serotonine is. De hoogste affiniteit van mescaline, MDMA en ibogaïne is voor respectievelijk de Alpha-2C, Imidazoline 1 en Sigma-2 receptoren. Daarbij liet slechts een van de 35 stoffen een echt selectieve receptoraffiniteit zien. Het ging hier om het atypische psychedelicum Salvinorine A, dat enkel invloed heeft op de κ-opioïde receptor (KOR) (Ray, 2010). Al de andere 34 geteste substanties waren meer promiscue met het scala aan receptoren dat ze beïnvloeden.

Op basis van de paper van Ray uit 2010 kunnen we stellen dat psychedelica inderdaad op een diverse waaier van receptoren inwerken. Hoewel phenylalkylamines selectiever zijn dan ergolines of tryptamines, vallen enkel DOB en MEM tegenwoordig binnen de categorie van radicaal selectieve psychedelica, omdat ze erg selectief en het minst promiscue zijn. Bovendien zet dit onderzoek het vage begrip van de complexiteit van psychedelica in de verf binnen de wereld van de moleculaire farmacologie. In de jaren ‘90 gebruikte men altijd DOI om de moleculaire mechanismes van hallucinogenen te illustreren, omdat algemeen werd aangenomen dat het een selectieve 5HT2-agonist was (Glennon, et al., 1991; Darmani, et al., 1994). Maar het onderzoek van Ray liet zien dat DOI de meest promiscue van alle psychedelische stoffen is. Daarom is het belangrijk om, bij het onderzoeken van papers over de relatie tussen psychedelica en serotonine die voor 2010 zijn gepubliceerd, na te gaan of de auteurs veronderstelden dat het gebruikte psychedelicum selectief was of niet.

De nadruk zou niet moeten liggen op de link tussen een psychedelicum en diens favoriete receptor, maar op het mechanisme als geheel. Het is niet genoeg om te stellen dat de bewustzijnsverandering aan de agonistische effecten van de 5HT2A-receptor ligt. Lisuride, een drug die doorgaans wordt gebruikt bij de ziekte van Parkinson, is ook een 5HT2A-agonist en reguleert dezelfde corticale neuronen als deze klassieke hallucinogenen, maar het is niet psychoactief (Gonzalez-Maeso, et al., 2007). Het verschil tussen de hallucinogene en niet-hallucinogene eigenschappen ligt aan de regulering van proteïne-subunits en cytoplasmatische enzymen. Het is cruciaal om te onthouden dat de essentie van het mechanisme niet ligt in de wijze waarop de receptor wordt gemanipuleerd, maar hoe de zenuwbaan in zijn geheel beïnvloed wordt.

Dit artikel wil het belang van serotonine in het begrijpen van psychedelische mechanismen of van de neurobiologie van de geest niet zomaar afwijzen. Immers, het gebruik van de 5HT2A-antagonist ketanserine kan de psychedelische werking van hallucinogene 5HT2A-agonisten, zoals LSD en DOI, belemmeren (Sadzot, et al., 1989; Borroto-Escuela, et al., 2014). Wanneer proefpersonen werden behandeld met ketanserine voordat ze psilocybine binnenkregen, volgden er ook geen hallucinogene effecten. Maar de andere effecten van psilocybine, zoals de afname van het vermogen om meerdere objecten te volgen en de afname in stimulatie en waakzaamheid, werden niet door de ketanserine aangetast. Dit laat zien hoe niet-5-HT2 receptorsites een aantal van de zichtbare mentale effecten van psilocybine veroorzaken (Carter, et al., 2005). Belangrijker nog laat het zien dat de hallucinaties opgewekt door de 5HT2A-receptoren ook bepaald worden door interacties van de drug met de niet-5HT receptor subtypes. Het is tijd voor neurowetenschappers om te kijken naar de zenuwbanen die stroomafwaarts liggen ten opzichte van de 5-HT2A-receptoren, niet alleen om te begrijpen hoe LSD en psilocybine hallucinaties veroorzaken, maar ook hoe ze gemoduleerd worden.

Om samen te vatten, Ray’s paper uit 2010 laat zien dat niet alle serotonerge agonisten leiden tot psychedelische effecten, en niet alle hallucinogenen serotonerge agonisten zijn. Het principe van de zoektocht van de dronkaard, die zijn sleutels enkel zoekt onder de straatlantaarn ondanks het feit dat ze aan de overkant in het donker liggen, beschrijft de huidige staat van de neurowetenschappelijke gemeenschap. Te vaak hebben de vragen in het veld van de neurowetenschap te maken met een van de neurotransmitters die we begrijpen, en niet met de minder bekende receptoren zoals imidazole en sigma. Net zoals bij de complexe correlatie tussen genen en stoornissen, moet men zich ervoor hoeden om een te simpele link te leggen tussen de psychedelische ervaring en haar neurotransmitters. Hoewel we moeten erkennen dat serotonine duidelijk heeft gemaakt dat gedrag voor een groot deel door neurochemie wordt bepaald, moeten de overige biochemische processen ook worden erkend. Om een globaal begrip te krijgen van de complexiteit van de mechanismen van psychedelische stoffen, moet de complete puzzel van het brein worden ontrafeld. Serotonine is niet de “Heilige Graal” van de neurotransmitters, maar een van de vele specifieke componenten.

Referenties:

Bethesda, 1998. Genes and Diseases. National Center for Biotechnology Information : s.n.

Borroto-Escuela, D. et al., 2014. Hallucinogenic 5-HT2AR agonists LSD and DOI enhance dopamine D2R protomer recognition and signalling of D2-5-HT2A heteroreceptor complexes.. Biochem Biophys Res Commun, 443(1), pp. 278-284.

Ciranna, L., 2006. Serotonin as a Modulator of Glutamate- and GABA-Mediated Neurotransmission: Implications in Physiological Functions and in Pathology. Current Neuropharmacology, 4(2), pp. 101-114.

Darmani, N., Mock, O., Towns, L. & Gerdes, C., 1994. The head-twitch response in the least shrew (Cryptotis Parva) is a 5-HT2- and not a 5-HT1C-mediated phenomenon. Pharmacol Biochem Behav, Volume 48, pp. 383-96.

Feijó, F. de M., Bertoluci, M. & Reis, C., 2011. Serotonin and hypothalamic control of hunger: a review. Rev Assoc Med Bras., 57(1), pp. 74-7.

Glennon, R., Darmani, N. & Martin, B., 1991. Multiple populations of serotonin receptors may modulate the behavioral effects of serotonergic agents. Life Science, Volume 45, pp. 2493-8.

Gonzalez-Maeso, J. et al., 2007. Hallucinogens Recruit Specific Cortical 5-HT2A Receptor Mediated Signalling Pathways to Affect Behavior. Neuron, 53(3), pp. 439-452.

Halberstadt, A. L. & Geyer, M. A., 2011. Multiple receptors contribute to the behavioral effects of indoleamine hallucinogens. Neuropharmacology, 61(3), pp. 364-381.

Harmon, K., 2009. When Grasshoppers Go Biblical: Serotonin Causes Locusts to Swarm. Scientific American, 30 January.

Kolb, B. & Whishaw, I., 2003. Fundamentals of Human Neuropsychology. 5th Edition ed. New York: Worth Publishers.

Miller, R. J., 2014. Drugged: The Science and Culture Behind Psychotropic Drugs. 1st edition ed. Oxford University: s.n.

Ray, T. S., 2010. Psychedelics and the Human Receptorome. PLOS, p. 10.1371.

Sadzot, B. et al., 1989. Hallucinogenic drug interactions at human brain 5-HT2 receptors: implications for treating LSD-induced hallucinogenesis.. Psychopharmacology (Berl), 98(4), pp. 495-9.

Wingen, M. et al., 2008. Sustained attention and serotonin: a pharmaco-fMRI study. Human Psychopharmacology, 23(3), pp. 221-230.

Young, S. & Leyton, M., 2002. The role of serotonin in human mood and social interaction. Insight from altered tryptophan levels. Pharmacol Biochem Behav, 71(4), pp. 857-865.

[/fusion_builder_column][/fusion_builder_row][/fusion_builder_container]

Stichting OPEN in Vrij Nederland

Vrij NederlandIn het laatste nummer van Vrij Nederland (12 december 2015) komt Stichting OPEN uitgebreid aan bod in een artikel over de gestage opkomst van psychedelisch onderzoek. In haar artikel “Trippen op recept” spreekt journaliste Freke Vuijst eerst met Dinah Bazer, een kankerpatiënte die dankzij haar psilocybinebehandeling haar doodsangst voorgoed wist te verjagen. Bazer was een van de proefpersonen van de studie aan de New York University over psilocybine voor de behandeling van doodsangst bij kankerpatiënten. Stephen Ross, een van de hoofdonderzoekers van de NYU-studie, noemt het succes van de psilocybinebehandelingen in zijn studie zonder meer indrukwekkend. Neal Goldsmith, co-organisator van het Horizons-symposium, dat in oktober plaatsvond in New York, en waar Vuijst Stephen Ross en zijn patiënte sprak, is het volmondig eens met deze laatste. “De data uit de studies zijn soms haast niet te geloven, zo overtuigend zijn ze,” legt hij uit. Terwijl de medische wereld volgens hem geen antwoord heeft op bijvoorbeeld post-traumatische stressstoornis (PTSS), en de psychiatrie zelden iets kan genezen, maakt hij zich sterk dat MDMA wel werkt. De onderzoeken naar de behandeling van doodsangst met psilocybine et die van PTSS met MDMA zijn momenteel de verst gevorderde.

Het artikel schetst vervolgens een kort historisch overzicht van de ‘eerste golf’ van het psychedelisch onderzoek tussen 1950 en 1970, waar president Nixon een einde aan stelde. Dat had niets te maken met de resultaten ervan: “Het was de counterculture revolution van de jaren zestig die de autoriteiten tot een algeheel verbod aanzette.” Ook in Nederland kende psychedelische therapie in die tijd een bloeiperiode, voornamelijk met het werk van psychiater Jan Bastiaans met overlevenden van de concentratiekampen uit WOII. Er kwam echter forse kritiek op de wetenschappelijkheid van de werkmethoden van Bastiaans. Joost Breeksema, voorzitter van Stichting OPEN, beaamt dat Bastiaans het imago van psychedelisch onderzoek in Nederland geen goed heeft gedaan, maar wijt het huidige gebrek aan onderzoek in Nederland vooral aan onbekendheid met moderne research over het onderwerp en blijvende associaties met hippies en muziek.

Ondertussen vordert het MDMA-onderzoek vrij snel. Volgens Rick Doblin, oprichter van MAPS, komt de goedkeuring van de Amerikaanse Food and Drug Administration er in 2021, en kan vanaf dan een netwerk van psychedelische therapieklinieken worden opgericht. Als voordelen van MDMA noemt hij het feit dat de ervaring minder ingrijpend en vreemd is dan bij de meer klassieke psychedelica, en dat er minder stigma aan vastkleeft.

Eerst moeten MDMA en psilocybine nog door het fase 3-onderzoek dat nu op til staat, waarbij de stoffen op een veel groter aantal patiënten worden getest. Dergelijke studies kosten hopen geld, en worden noch door de overheid noch door de farmasector gefinancierd. Die laatste is immers niet geïnteresseerd in stoffen waarop het patent vervallen is. In de VS bestaat er een traditie van grote non-profitorganisaties zoals MAPS, die privéfinanciering kunnen bieden, en zijn er belangrijke researchuniversiteiten die onderzoek voeren. In Nederland valt men traditioneel eerder terug op overheidsgeld. Bijgevolg gaat het onderzoek naar bijvoorbeeld MDMA eerder over de schadelijkheid ervan dan over mogelijke therapeutische toepassingen. Een toenemende interesse hiervoor bestaat wel: de lezingen en symposia van Stichting OPEN trekken volle zalen. Maar voorlopig komt het onderzoek naar psychedelische therapie in Nederland slechts moeizaam van de grond.

Sacred Knowledge – Psychedelics and Religious Experiences

Antidepressant Effects of a Single Dose of Ayahuasca in Patients With Recurrent Depression: A SPECT Study

Abstract

Ayahuasca is an Amazonian botanical hallucinogenic brew which contains dimethyltryptamine, a 5-HT2A receptor agonist, and harmine, a monoamine-oxidase A inhibitor. Our group recently reported that ayahuasca administration was associated with fast-acting antidepressive effects in 6 depressive patients. The objective of the present work was to assess the antidepressive potentials of ayahuasca in a bigger sample and to investigate its effects on regional cerebral blood flow. In an open-label trial conducted in an inpatient psychiatric unit, 17 patients with recurrent depression received an oral dose of ayahuasca (2.2 mL/kg) and were evaluated with the Hamilton Rating Scale for Depression, the Montgomery-Asberg Depression Rating Scale, the Brief Psychiatric Rating Scale, the Young Mania Rating Scale, and the Clinician Administered Dissociative States Scale during acute ayahuasca effects and 1, 7, 14, and 21 days after drug intake. Blood perfusion was assessed eight hours after drug administration by means of single photon emission tomography. Ayahuasca administration was associated with increased psychoactivity (Clinician Administered Dissociative States Scale) and significant score decreases in depression-related scales (Hamilton Rating Scale for Depression, Montgomery-Asberg Depression Rating Scale, Brief Psychiatric Rating Scale) from 80 minutes to day 21. Increased blood perfusion in the left nucleus accumbens, right insula and left subgenual area, brain regions implicated in the regulation of mood and emotions, were observed after ayahuasca intake. Ayahuasca was well tolerated. Vomiting was the only adverse effect recorded, being reported by 47% of the volunteers. Our results suggest that ayahuasca may have fast-acting and sustained antidepressive properties. These results should be replicated in randomized, double-blind, placebo-controlled trials.
Sanches, R. F., de Lima, O. F., Dos Santos, R. G., Macedo, L. R., Maia-de-Oliveira, J. P., Wichert-Ana, L., … & Hallak, J. E. (2015). Antidepressant Effects of a Single Dose of Ayahuasca in Patients With Recurrent Depression: A SPECT Study. Journal of clinical psychopharmacology. http://dx.doi.org/10.1097/JCP.0000000000000436
Link to full text

The epistemic innocence of psychedelic states

Abstract

One recent development in epistemology, the philosophical study of knowledge, is the notion of ‘epistemic innocence’ introduced by Bortolotti and colleagues. This concept expresses the idea that certain suboptimal cognitive processes may nonetheless have epistemic (knowledge-related) benefits. The idea that delusion or confabulation may have psychological benefits is familiar enough. What is novel and interesting is the idea that such conditions may also yield significant and otherwise unavailable epistemic benefits. I apply the notion of epistemic innocence to research on the transformative potential of psychedelic drugs. The popular epithet ‘hallucinogen’ exemplifies a view of these substances as fundamentally epistemically detrimental. I argue that the picture is more complicated and that some psychedelic states can be epistemically innocent. This conclusion is highly relevant to policy debates about psychedelic therapy. Moreover, analysing the case of psychedelics can shed further light on the concept of epistemic innocence itself.

Letheby, C. (2016). The epistemic innocence of psychedelic states. Consciousness and cognition, 39, 28-37. http://dx.doi.org/10.1016/j.concog.2015.11.012
Link to full text

The Serotonin Infatuation

serotonin picMuch like the Holy Grail symbolised well-being, infinite wealth, and abundance of food in Arthurian literature, today the infamous neurotransmitter, serotonin, is linked with mood, attention, hunger and more (Young & Leyton, 2002; Wingen, et al., 2008; Feijó, et al., 2011). However, today serotonin may be accredited with too much. Just as Harmon (2009) described the effect of serotonin on the swarm process of locusts, serotonin seemingly has had the same effect on our neuroscientists (Harmon, 2009).

Serotonin is one of three reptilian monoamine neurotransmitters, alongside dopamine and norepinephrine (Kolb & I.Q., 2003). The serotonin receptor has seven main subfamilies, more than the other two monoamines, and has even more subtypes. Although serotonin is indeed a crucial neurotransmitter, it is important to note that it is merely a modulator of other neurotransmitters. Serotonin fine-tunes the action of glutamate and GABA, the principal neurotransmitters, mediating the excitatory and inhibitory signals in the brain. The exception is 5HT3, which mediates the flow of ions (Ciranna, 2006). As a multifunctional neuromodulatory transmitter, to truly understand its function, there is a need to better understand the second-messenger pathways downstream to reveal the successive key biochemical steps. Serotonin is not the magic bullet for mental health, as penicillin was for gram-negative bacteria. It may only be one of several fingers on the trigger.

Much of serotonin’s claim to fame in the world of mental health is related to LSD findings. Only four years after Hofmann’s famous discovery, LSD was used to model psychosis (Miller, 2014). Almost a decade later, the remarkable similarity between the structures of LSD and serotonin led to the discovery of serotonin in the brain. From this, the scientific community began to infer the relationship between the brain’s chemistry and behavioural outcomes (Miller, 2014). More than 70 years later, there are over one million papers that contain ‘serotonin’ in their titles.

It is reminiscent of the days leading up to the first full sequencing of the human genome, when the scientific community was excited about finding the faulty gene that led to each and every illness. Currently, the neuroscience community has become infatuated with a simple molecule’s role in a variety of complex mental disorders. However, today we understand that disorders are polygenic, and the outcome is dependent on several variables, such as protein production, compensatory mechanisms and environmental influences (Bethesda, 1998). Serotonin may play a significant role in mental illness, but several other factors likely also influence the outcome of disease presentation. The modelling of schizophrenic-like psychosis induced by phencyclidine (PCP) and ketamine demonstrates that glutamate receptors and dopamine can also play a pivotal role in mental health (Javitt, 2007). As much as the driver plays a key role in manoeuvring an automobile, some researchers have not yet acknowledged the importance of the fuel, engine, road taken and other seemingly mundane variables.

Thomas Ray expands extensively on the variegated mannerism of psychedelics. In his paper on “Psychedelics and the Human Receptorome”, he illustrates the multifaceted interaction that psychedelics have with various receptors (Ray, 2010). In conjunction with the National Institute of Mental Health-Psychoactive Drug Screening Program (NIMH-PDSP), he has presented the receptor affinity and promiscuity for 35 psychedelic drugs. The results demonstrate that these 35 drugs do not selectively interact with a single receptor, but rather with a wide range of different classes simultaneously. Even compounds with very similar molecular structures have very different mechanisms (See figure 1 for a comparison between DOB and DOI).

[fusion_builder_container hundred_percent=”yes” overflow=”visible”][fusion_builder_row][fusion_builder_column type=”1_1″ background_position=”left top” background_color=”” border_size=”” border_color=”” border_style=”solid” spacing=”yes” background_image=”” background_repeat=”no-repeat” padding=”” margin_top=”0px” margin_bottom=”0px” class=”” id=”” animation_type=”” animation_speed=”0.3″ animation_direction=”left” hide_on_mobile=”no” center_content=”no” min_height=”none”]

ray receptorome
Figure 1: Ray (2010)

For example, DOB’s highest affinity is for 5HT2B, 5HT2A and 5HTC, and it interacts to a lesser extent with 21 other receptors. As for DOI, its highest affinity is for 5HT2C and two other non-serotonergic receptors, with 23 other receptors affected (Ray, 2010). What is more surprising is that for many popular hallucinogens and empathogens, their highest affinity was not necessarily for serotonin. The highest affinity of mescaline, MDMA and ibogaine was for Alpha-2C, Imidazoline 1 and Sigma-2 receptors, respectively. In addition, only one of the 35 drugs displayed a selective receptor affinity, which was the atypical psychedelic Salvinorin A, which solely affects the κ-opioid receptor (KOR) (Ray, 2010). All other 34 tested substances were more promiscuous with their range of receptors.

From Ray’s 2010 paper, we can tell that psychedelics in fact interact with a diverse range of receptors. Although phenylalkylamines are more selective than ergolines and tryptamines, only DOB and MEM can fit today’s framework of radically selective psychedelics, as they are highly selective and the least promiscuous. Furthermore, this study truly highlights the molecular pharmacology community’s vague understanding of the complexity of psychedelics. In the 1990s, DOI was the hallucinogen of choice when illustrating the molecular mechanisms of hallucinogens, as it was widely assumed to be a 5HT2 selective agonist (Glennon, et al., 1991; Darmani, et al., 1994). However, Ray’s study revealed that DOI is the most promiscuous of all psychedelic substances. Hence, when reviewing papers that solely focus on the relationship between psychedelics and serotonin prior to 2010, it’s important to verify whether the authors presumed the psychedelic at hand was selective or not.

The emphasis should not be on the relationship between a psychedelic and its receptor of choice, but on its mechanism as a whole. It is not enough to state that the alteration of consciousness lies within the agonistic effects on the 5HT2A receptor. Lisuride, a drug typically used for Parkinson’s disease, is also a 5HT2A agonist and regulates the same cortical neurons as these classic hallucinogens, but leads to no psychoactive effects (Gonzalez-Maeso, et al., 2007). The difference between the hallucinogenic and non-hallucinogenic properties lies within the regulation of protein subunits and cytoplasmic enzymes. It is crucial to bear in mind that the essence of the mechanism is not how the receptor is manipulated, but how the whole neuronal pathway is influenced.

This article does not mean to simply dismiss the importance of serotonin in the understanding of psychedelic mechanisms or the neurobiology of the mind. Indeed, the use of the 5HT2A antagonist ketanserin alone can inhibit the psychedelic actions of hallucinogenic 5HT2A agonists, such as LSD and DOI (Sadzot, et al., 1989; Borroto-Escuela, et al., 2014). When subjects were treated with ketanserin prior to psilocybin ingestion, the hallucinogenic effects also did not ensue. However, the other effects of psilocybin, such as multiple-object tracking impairment and reduction of arousal and vigilance, were not affected by the ketanserin. This demonstrates how non-5-HT2 receptor sites mediate some of the perceptible mental effects of psilocybin (Carter, et al., 2005). More importantly, it indicates that the hallucinations induced by 5HT2A receptors are moderated by the drug’s interactions with non-5HT receptor subtypes as well. It is time for neuroscientists to look at the pathways downstream of 5-HT2A receptors to not only understand how LSD and psilocybin induce hallucinations, but how they are modulated as well.

In sum, Ray’s 2010 paper illustrates that not all serotonergic agonists lead to psychedelic effects, and not all hallucinogens are serotonergic agonists. The principle of the drunkard’s search, in which the drunk will only look for his keys under the streetlight although his keys are across the street in the dark, describes the current state of the neuroscience community. The questions in the field of neuroscience are too often linked only to the neurotransmitters we understand, but not the lesser known receptors such as imidazole and sigma. Much like the complex correlation between genes and disorders, one must be cautious not to draw an all too simple connection between the psychedelic experience and its neurotransmitters. Although we do have serotonin to praise for demonstrating that behaviour is largely determined by neurochemistry, its partner biochemical processes must be acknowledged as well. In order to fully understand the complexity of the mechanisms of psychedelic tools, the complete tapestry of the brain needs to be unravelled. Serotonin is not the “Holy Grail” of neurotransmitters, but one of the many specific components.

References:

Bethesda, 1998. Genes and Diseases. National Center for Biotechnology Information : s.n.
Borroto-Escuela, D. et al., 2014. Hallucinogenic 5-HT2AR agonists LSD and DOI enhance dopamine D2R protomer recognition and signalling of D2-5-HT2A heteroreceptor complexes.. Biochem Biophys Res Commun, 443(1), pp. 278-284.
Ciranna, L., 2006. Serotonin as a Modulator of Glutamate- and GABA-Mediated Neurotransmission: Implications in Physiological Functions and in Pathology. Current Neuropharmacology, 4(2), pp. 101-114.
Darmani, N., Mock, O., Towns, L. & Gerdes, C., 1994. The head-twitch response in the least shrew (Cryptotis Parva) is a 5-HT2- and not a 5-HT1C-mediated phenomenon. Pharmacol Biochem Behav, Volume 48, pp. 383-96.
Feijó, F. de M., Bertoluci, M. & Reis, C., 2011. Serotonin and hypothalamic control of hunger: a review. Rev Assoc Med Bras., 57(1), pp. 74-7.
Glennon, R., Darmani, N. & Martin, B., 1991. Multiple populations of serotonin receptors may modulate the behavioral effects of serotonergic agents. Life Science, Volume 45, pp. 2493-8.
Gonzalez-Maeso, J. et al., 2007. Hallucinogens Recruit Specific Cortical 5-HT2A Receptor Mediated Signalling Pathways to Affect Behavior. Neuron, 53(3), pp. 439-452.
Halberstadt, A. L. & Geyer, M. A., 2011. Multiple receptors contribute to the behavioral effects of indoleamine hallucinogens. Neuropharmacology, 61(3), pp. 364-381.
Harmon, K., 2009. When Grasshoppers Go Biblical: Serotonin Causes Locusts to Swarm. Scientific American, 30 January.
Kolb, B. & Whishaw, I., 2003. Fundamentals of Human Neuropsychology. 5th Edition ed. New York: Worth Publishers.
Miller, R. J., 2014. Drugged: The Science and Culture Behind Psychotropic Drugs. 1st edition ed. Oxford University: s.n.
Ray, T. S., 2010. Psychedelics and the Human Receptorome. PLOS, p. 10.1371.
Sadzot, B. et al., 1989. Hallucinogenic drug interactions at human brain 5-HT2 receptors: implications for treating LSD-induced hallucinogenesis.. Psychopharmacology (Berl), 98(4), pp. 495-9.
Wingen, M. et al., 2008. Sustained attention and serotonin: a pharmaco-fMRI study. Human Psychopharmacology, 23(3), pp. 221-230.
Young, S. & Leyton, M., 2002. The role of serotonin in human mood and social interaction. Insight from altered tryptophan levels. Pharmacol Biochem Behav, 71(4), pp. 857-865.
[/fusion_builder_column][/fusion_builder_row][/fusion_builder_container]

interested in becoming a trained psychedelic-assisted therapist?

Indigenous Talk: Fulni-ô Culture & Jurema - Online Event - Dec 12th