Why might psychedelic-assisted therapy be effective in treating depression?
An investigation from the philosophical school of phenomenology
Part One: The Phenomenology of Depression
The accounts of the experience of depression provided by diagnostic journals seem decidedly insufficient. Remarkably, eight of the nine possible symptoms listed in the DSM-5 are phenomenological in nature, deliberately or otherwise, but they are generally either unexplained or circular. In particular, it is not obvious what is meant by the term ‘depressed mood’, nor how it could possibly define ‘depression’ [1].
Existential Change
My contention is that major depressive disorder is not a cluster of symptoms, as traditionally postulated, but some one thing more fundamental: an underlying, all-encompassing disturbance of the overall structure of experience. Matthew Ratcliffe calls this an ‘existential change’ [2], and it has profound effects on all aspects of being-in-the-world, including those we do not notice when they are intact. Consequently, one’s overall unified experience of the world has a different ‘style’ to it, to borrow from Merleau-Ponty’s language [3]. The experience is difficult to articulate [4] because our consensus language presupposes the very structures and concepts which are disrupted.
“You’ve lost something that people don’t even know is. That’s why it’s so hard to explain.” [5]
I suggest that this existential change has (at least) three aspects.
First Aspect: Corporealization of the Body
“Why do they call it a ‘mental’ illness? The pain isn’t just in my head; it’s everywhere.” [6]
A fact stressed almost invariably by testimonies—but conspicuously absent from diagnostic criteria—is that the existential change in depression is embodied. Complaints of heaviness, fatigue, pain, and numbness are common, while some people even struggle to discern whether they have depression or influenza. The following are some answers to the question, ‘How does your body feel when you are depressed?’ [7].
“My body wouldn’t co-operate.”
“slow no energy really old dead fat”
“A lot of people have this impression that depression is a purely mental illness, and I can’t explain it but it totally affects you physically as well and your body just goes into meltdown mode.”
“I can feel it as if it were more than a metaphorical illness, as though it were tangible.”
Thomas Fuchs convincingly characterizes this as the ‘corporealization’ of the body [8].
We experience the world not as detached observers—as merely our ‘minds’—but ‘with, through, and because of, our living bodies’, as Anil Seth puts it [9]. Without the body, there can be no feelings, emotions or moods, no goals, plans or meanings, and so it is meaningless to talk of ‘physical’ versus ‘mental’ pain, ‘for pain can only be experienced by an embodied subject’ [10]. However, whilst the body is normally the transparent medium through which we experience the world, it can instead become an object of our experience. To give an example used many times by Merleau-Ponty in various works, if one hand strokes the other, we have a quite different feeling of the one touching to the one being touched. In depression, it is the feeling of the stroking hand that is disturbed, as the body takes on ‘pure materiality and turn[s] into an obstacle’ [11], blocking the exchange between body and environment and making all (inter)action jarring and difficult. Features of the body normally not noticed, such as weight and density, become painfully explicit, and the body feels generally congealed, and constricted: exhaustion, aching, numbness, heaviness, and sickness result. The body has become corporealized.
Second Aspect: Disconnection from the World
“Life is about connection. There is nothing else. Depression is the opposite; it is an illness defined by alienation.” [12]
Ordinarily, one feels comfortably immersed in the world, with a prereflective confidence in one’s place in it and a basic familiarity with one’s activities, normally taken for granted. Without this, the individual feels cut off and unable to engage with the world, like a prisoner, castaway, or ‘ghost’.
“The disconnection … [is] like being in a bubble with no sound or colour, and a complete lack of familiarity in everything, even in places I know well, like my home. Even people seem very alien.” [13]
“It is the glass wall that separates us from life, from ourselves, that is so truly frightening in depression. … It is like living in a parallel universe but a universe so devoid of familiar signs of life that we are adrift, lost.” [14]
Specifically, almost everyone mourns the loss of the ability to connect to other people.
“I feel less connected to people around me—completely alone even in a crowd. … They seem more distant and collectively living their lives around me, as if I am not an active participant in my life.” [15]
“It seemed to me the basic definition of any mental illness, this persistent, painful inability to simply be with someone else.” [16]
Third Aspect: Loss of Possibility
“The world holds no possibilities for me when I’m depressed. Every avenue I consider exploring seems shut off.” [17]
A further feature of many reports of depression is the felt absence of crucial types—not just tokens—of possibility, normally taken for granted [18]. Take the general possibility that things could change for the better: ordinarily, this is integral to a negative experience, as we can imagine ways it might have gone differently and have an underlying confidence that it will change. Without this, though, reality loses any sense of contingency, and so the state of depression seems inevitable, never-ending, and therefore hopeless. The very possibility of possibility, if you like, has been lost.
“It is impossible to feel that things will ever be different. When I’m not depressed, other possibilities exist. … When depressed, these possibilities simply do not exist. Life will never end, or change.” [19]
“My father would assure me, sunnily, that I would be able to do it all again, soon. He could as well have told me that I would soon be able to build myself a helicopter out of cookie dough and fly on it to Neptune.” [20]
The world that we normally find ourselves comfortably immersed in is not a world of neutral, passive objects. It is a world of phenomena that ‘shine forth’ (phainesthai) with significance by suggesting meaningful possibilities for activity. James Gibson coins the term ‘affordances’ to denote what this meaningful world ‘offers the animal, what it provides or furnishes, either for good or ill’ [21]. Fire affords the possibility of warming; a roof, shelter; a bridge, crossing an obstacle. When the affordances of the world are inaccessible, however, the possibilities of objects no longer shine forth. One’s experience of being-in-theworld loses its sense of contingency, because there is no sense that there is more possibility to the world than currently being manifested; what you see is all there is. The ‘style’ of the world goes from being alive, inviting, pregnant, dynamic and changeable, to dead, mute, meaningless, static and unreachable. This, I propose, is precisely what happens in depression.
“You’ve lost the invitation to live that the universe extends to us at every moment.” [22]
Interim Conclusion
“The world holds no possibilities for me when I’m depressed. Every avenue I consider exploring seems shut off.” [17]
Depression is an existential change which manifests itself simultaneously as a felt sense of a) the corporealization of the body, b) the loss of possibility, and c) disconnection from the world. These are three ways of talking about the same thing, because one’s experience of bodily connection to the world is identical to one’s experience of worldly possibilities. As an embodied being in the world, one is connected to the world through the possibilities it affords relative to one’s bodily capacities; a seat is a seat by virtue of being sit-on-able for the right organism [23].
One’s healthy bodily experience of being-in-the-world has a foundation of connection and possibility: a ‘basis of a pre-reflective attunement’ [24] with a world pulsating with meaning, affording possibilities which invite and respond to appropriate bodily behaviour. Thus, the body and the affordances of the world resonate with each other; one’s organism is a delicate ‘sort of sounding board, which every change of our consciousness, however slight, may make reverberate’, as William James puts it [25]. Fuchs refers to this as a ‘resonance body’ [26] but since a living body separated from its ‘mind’ is as meaningless a notion as the reverse, I prefer resonant mind-body. Depression is the ‘detunement’ (Verstimmung) of the resonant mind-body to the affordances of the world. The result is the felt absence of connection and possibility usually intrinsic to, and presupposed by, one’s bodily experience of being-in-the-world.
Part Two: The Phenomenology of Psilocybin
‘Psilocybin-assisted therapy’ (PAT hereafter), consists of several talking therapy sessions sandwiching one or two guided doses of the psychedelic compound psilocybin. Notwithstanding the importance of the preparation and integration sessions, this paper focuses instead on the psilocybin experience itself. The patient is usually on a sofa for the 4–8-hour duration, wearing an eye mask and listening to music, with a professional there to ‘hold the space’. In the last few years, clinical trials involving PAT for depression have produced promising results [27]. In 2020, Davis et al. found responses—sustained months later—that were 2.5 times greater than in conventional psychotherapy, and over four times greater than other pharmacological treatments [28]. However, there has been little attempt to explain, from a phenomenological viewpoint, why so many patients find the experience so effective in alleviating their depression. To my knowledge, this is the first paper to explicitly study any form of psychedelic-assisted therapy through the lens of the philosophical school of phenomenology. Despite the extreme ineffability universally attributed to the experience and the influence of ‘set and setting’ (the individual’s mindset and the environmental setting) on what is a heterogeneous phenomenon, I maintain that the same three aspects altered in depression—the body, possibility, and connection—undergo similarly profound changes in the psilocybin experience.
First Aspect: The Body
“You don’t understand it strictly in your head. You understand it as a being, as a body.” [29]
As with depression, testimonies emphasize the essentially embodied nature of the experience. The world of psilocybin is described as one in which all the senses of the mind and body unite: ‘seeing’, ‘thinking’ and ‘feeling’ are continuous.
“One is really having a vision with one’s whole body … It’s not merely a matter of seeing in a vast space; it’s a matter of feeling to a degree that defies description.” [30; non-clinical setting]
The feeling is often one of lightness, openness and vitality in the body”
“It was a relief, physical, I felt lighter afterwards.” [31]
“I felt spatial, not depressed.” [32]
“Never had an orgasm of the soul before.” [33]
Second Aspect: The Body
“[My] sense of the concrete destabilised … there’s a reality beneath the reality of ordinary perceptions.” [34]
Another important feature is the tendency of psilocybin to reveal— nakedly and forcibly—types of possibilities that were previously inconceivable. This shakes one’s pre-reflective sense of what is possible or impossible in the world of experience, demanding an accommodation of the fact that there is far more to the world than was previously apparent.
“Now I am aware that there is a whole other ‘reality.’ Compared to other people, it is like I know another languag35 I had a sense of initiation into dimensions of existence most people never know exist.” [36]
“It was like the light switch being turned on in a dark house.” [37]
“It’s as though we lived in a universe where, if you just reached into your right pocket with your left hand, rather than pull out your wallet you’d pull out the Andromeda Galaxy.” [38; non-clinical setting]
This ‘more’ includes the possibility in one’s range of experience. One participant ‘experienced all the emotions I know how to experience’; another, ‘all of them, all of them. Every possible emotion’ [39]. One person who previously felt no bodily sensations at all called his experiences during the dose ‘pure sensory, tactile, sexual bliss’, as another found that ‘everything felt like it did when I was a kid, the blanket felt brilliant’ [40].
Indeed, returning to a childlike experience is a common experience, amid a general theme of rediscovering lost mystery in the world. This is a symptom of the crucial fact that psilocybin allows one to discover possibilities that are already and always there. Author Michael Pollan, for instance, was ‘struck by the fact that there was nothing supernatural’ about his (non-clinical) experience:
“No, all it took was another perceptual slant on the same old reality, a lens or mode of consciousness that invented nothing … [but was] disclosing the wonder that is always there … hidden in plain sight.” [41]
“It’s like waking up in the most profound way, that this is really what life is, it’s really like this. We’re just not noticing.” [42]
This realization that the possibilities of the world were intrinsic to it all along—waiting to be discovered—creates choice, leading to suggestions that psychedelics ought instead to be called ‘meaning enhancers’ [43] or ‘choice enhancers’ [44]. While Robin Carhart-Harris is fond of saying that psychedelics shake up the snow-globe, Mendel Kaelen likens one’s experience to a sled on a snowy slope, drawn into grooves where it has run down before; psilocybin provides a dumping of fresh powder [45].
“[It] returned me to the child’s sense of wonder… The universe was so great and there were so many things you could do and see in it that killing yourself seemed like a dumb idea.” [46]
Third Aspect: Connection
“People use words like ‘oneness’, ‘connectivity’, ‘unity’—I get it! I was part of something larger than anything I had ever imagined.” [47]
One’s whole experience of being-in-the-world is imbued with a profound, universal sense of (re)connection—to oneself, others and nature at large. This is generally received not intellectually as propositional knowledge, but as an overwhelming, visceral revelation. People describe ‘connecting back to myself again’, to ‘who they had been’; previous interests are often taken up again afterwards, and many feel ‘connected with a spiritual side’ in themselves, or that ‘I knew exactly who I was, I knew exactly what I was doing here’ [48]. Interpersonal connection is even more salient. For instance, in the above study, every single participant emphasized relational aspects and seeing their loved ones in a new way, as well as a shift ‘from feelings of separateness to interconnectedness’ [49]. This seems to come from seeing people ‘as they really are’, with ‘fresh insight’ [50]. One often feels a connection to strangers, too, to the whole human race:
“We’re all kind of a greater whole … I felt like I could reach out to anybody and connect with them.” [51]
“Now there’s a greater sense of ‘we’re all in the same boat’.” [52]
Equally prominent is a strong feeling of ultimate connection to nature at large. People often describe realizing—feeling—for the first time that ‘it wasn’t an all-powerful world and universe against me’, [53] but rather that they are an integral and continuous part of it, finding their ‘place in the cosmos’ or feeling ‘very aware that I belonged there’ in a way that is not ‘like talking about it, which makes it an idea, it was, like, experiential’ [54].
“[I was] deep inside and fully implicated in this scene, one more being in a relation to the myriad other beings and to the whole.” [55; non-clinical setting]
“Before I enjoyed nature, now I feel part of it. Before I was looking at it as a thing, like TV or a painting. You’re part of it, there’s no separation or distinction, you are it.” [56]
Intriguingly, a relation has been established between use of psychedelics and increased ‘nature relatedness’ (self-rated connection to nature) lasting years after the experience [57]. This further highlights the importance of connection in the experience, and the fact that it transcends the interpersonal.
Interim Conclusion
Two of the most salient aspects of the unified mind-body psilocybin experience are a powerful revelation of previously hidden possibility, and a deep sense of connection to all aspects of one’s reality. It is once again apparent that bodily experience, possibility, and connection are all inextricably linked. For instance, to feel that other people hold new possibility immediately creates connection:
“I was talking to strangers. I had these full long conversations with everybody I came into contact with.” [58]
“I would look at people on the street and think ‘how interesting we are’—I felt connected to them all.” [59]
Tellingly, the personality trait ‘openness’ (in the Big Five model) tends to be significantly increased in the long term by a psilocybin experience [60]: an almost unprecedented effect amongst adults. This trait—encompassing appreciation for new experiences and knowledge, broadness of imagination, and curiosity—is inextricable from feeling that the world holds possibility, which in turn is interdependent upon connection.
Part Three: What Conclusions Can Be Drawn?
Depression is a detunement of the resonant mind-body. The embodied connection and possibility usually intrinsic to, and presupposed by, one’s experience of being-in-the-world is absent. One feels this absence acutely, striving for connection and for possibilities that are inaccessible due to the corporealized bodily organism being out of sync with the affordances of the world. This is particularly painful in one’s interpersonal relationships. With no access to the possibility that things might improve, one feels hopeless, trapped forever in this state.
Psilocybin reveals to the depressed person, viscerally and undeniably, that their perspective of reality was incomplete: there is another side to the coin. Crucially, this new perspective on the world is a different window into the same room, revealing possibilities already and always there, so that afterwards the person feels that they are still in that same wondrous, contingent world, rather than having woken up from some dream. This helps to explain three important puzzles: the long-lasting effects of psilocybin; the consistent rating of this drug experience as one of the top five personally meaningful and spiritually significant experiences of one’s life [61]; and the curiously paradoxical reports in the months that follow, where people do in fact still feel symptoms, but are less distressed by them and better able to accept them.
“Things have gone downhill but not back … things are different, I am not the same, and that’s hard to explain.” [62]
70% of respondents in the above study said they retained a sense of well-being and meaning after symptoms returned, a result corroborated by Belser et al. [63]. I suggest that this is because people feel that their experience is not all there is, that reality has meaning and possibilities that are not always apparent.
The experience simultaneously reconnects the individual to their world of experience. For example, in the study by Watts et al., the 17 (out of 20) patients who said that the treatment was effective all said that a fresh sense of connection was a mediating factor, with connection to self and world deemed as important as connection to others [64]. Furthermore, the extent to which one experiences an ultimate connection to one’s entire world via a ‘mystical experience’ is positively associated with therapeutic success [65].
I propose that this revelation of possibility and connection is synonymous with the mind-body being ‘retuned’ to the affordances that lie latent in the world; it resonates with it. Indeed, it is extraordinary how many people use this terminology, without prompting. One subject said her ‘body was resonating … like a string on a violin’; another felt a new kind of ‘resonance’ with herself, feeling ‘more in touch with … myself that’s connected to everyone and everything’ [66]. Another felt his
“physical body trying to vibrate in unity with the cosmos … and, frustratingly, I felt like a guy who couldn’t dance … but the universe accepted it.” [67]
Further supporting this hypothesis is the extraordinary (though often neglected) significance attributed to music during the psilocybin experience, usually framed in the same terms of embodied resonance. It does not seem to be metaphorical.
“Music was really how everything was conveyed to me … everything that I experienced did not really happen in the English language, it kind of happened through the music.” [68]
“‘Listen’ doesn’t begin to describe what transpired between me and the vibrations of air … even to call it ‘music’ is to diminish what now began to flow, which was nothing less than the stream of human consciousness, something in which one might glean the very meaning of life.” [69; non-clinical setting]
Even more tellingly, Kaelen et al. found that the nature of the music experience in PAT—specifically, its ‘personal resonance’—was significantly predictive of reductions in depression. [70]
Discussion
This has been an exploration into the aspects of the psilocybin experience which may make it an effective treatment for many people with depression. I have focused on three key themes common and significant to both: connection, possibility, and the body. I maintain that depression consists of a single fundamental, existential change which can be talked of in terms of all three, and that psilocybin can be thought of in the same terms. While it would clearly be simplistic to call psilocybin the opposite of depression, I do suggest the following hypothesis: depression is the detunement of the resonant mind-body to the affordances of the world; at least in some cases where it is effective as a treatment, the psilocybin experience acts as a retuning of the resonant mind-body.
Implications
This model suggests that it is a mistake to assert, as Fuchs and Ratcliffe do, that the disconnection in depression is essentially interpersonal. Reports from those for whom treatment was effective—corroborated by long-term measures of nature relatedness and personality trait openness—stress important increases in feelings of connection to oneself and the natural world. Importantly,
“describing their depression, the patients had not spontaneously referred to feeling disconnected from nature. It seems rather they had not realized that they were missing it/disconnected from it until reminded of its value during and after their experience with psilocybin.” [71]
The loss of awareness of one’s connection to nature could therefore be an under-appreciated feature of depression.
My hypothesis lends support to other non-mechanistic treatments (such as yoga, dance therapy, mindfulness-based CBT and nature therapy) which could also target the mind-body’s resonance. Meditation, in particular, seems to have a synergistic effect with psilocybin [72]; indeed, considering the importance of the specifics of PAT and the limited experimentation until now, it is conceivable that PAT for depression could be even more effective. Bespoke treatments could combine, say, talking therapy, meditation, yoga, and psilocybin with a curated playlist. This last detail may prove especially fruitful, as music may be particularly important in retuning the resonant mind-body.
More speculatively, it could lend credence to the conviction of so many in the field that psychedelics—working antithetically to the shortcomings of the conventional approach [73]—can be the vanguard of a revolution in mental health. A new paradigm could be on the horizon wherein, as urged by Fuchs, mental illness will be treated not as a ‘state in the head’ but ‘regarded as alterations of the patient’s lived body, lived space, and being-with-others … an altered way of being in the world’ [74]. Moreover, the fact that psychedelics seem to be potentially effective in treating such a wide range of disorders—depression, anxiety, and OCD [75], PTSD [76], tobacco [77] and alcohol [78] addiction, and more—suggests that they may address a nuclear factor of all psychological dis-ease.
Limitations
First, I have used testimonies provided at various times relative to the experience, and have not explicitly differentiated acute from longer term effects (partly because it is often not obvious from the sources). Some standardization in both respects would be valuable. Second, many phenomenological features of both experiences have been omitted, as have the therapy sessions integral to PAT. It is beyond the scope of this paper to provide such a comprehensive account. Third, I have had to generalize and largely disregard the heterogeneity of both experiences. Fourth and finally, many of the testimonies used involve individuals with depression and terminal cancer: I have not addressed the influence of this variable, particularly pertaining to the sense of possibility.
• • •
POSTSCRIPT
This article was written three years ago and inevitably reflects some personal and collective ignorance compared to our current understanding of psychedelics. Were I to write this today, I would pay more attention to the role of setting and to the occurrence of challenging experiences and adverse events, and be slightly less enthusiastic about the big effect sizes seen in trials.
This paper was originally published in Psychedelic Press, and is available to view with a full list of references here.
Montgomery C (2021) Why might psilocybin-assisted therapy be effective in treating depression? An investigation from the philosophical school of phenomenology. Psychedelic Press, 34. 57–77