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Abstract

Psychedelic drugs are creating ripples in psychiatry as evidence accumulates of their therapeutic potential. An important question remains unresolved however: how are psychedelics effective? We propose that a sense of connectedness is key, provide some preliminary evidence to support this, and suggest a roadmap for testing it further.
COMMENTARY
Psychedelics and connectedness
R. L. Carhart-Harris
1
&D. Erritzoe
1
&E. Haijen
1
&M. Kaelen
1
&R. Watts
1
Received: 18 June 2017 /Accepted: 19 July 2017
#Springer-Verlag GmbH Germany 2017
Abstract Psychedelic drugs are creating ripples in psychiatry
as evidence accumulates of their therapeutic potential. An
important question remains unresolved however: how are psy-
chedelics effective? We propose that a sense of connectedness
is key, provide some preliminary evidence to support this, and
suggest a roadmap for testing it further.
We are in the midst of a cultural zeitgeist with regard to psy-
chedelic drugs such as psilocybin, LSD and DMT (ayahuasca)
(Carhart-Harris and Goodwin 2017). April 2017 featured the
largest ever conference on the topic, Psychedelic Science,in
Oakland, California, attended by 3000 people from over 40
different countries. Among the 175+ speakers were Tom Insel
(former director of the National Institute for Mental Health)
and Paul Summergrad (past president of the American
Psychiatric Association), speaking enthusiastically and en-
couragingly about the field, symbolic in some sense of its
present main-streaming(Carhart-Harris and Goodwin
2017).
The theme of connectedness was pervasive at Psychedelic
Science, featuring consistently among speakerspresentations.
To our knowledge, the concept was first given clear emphasis
in psychedelic therapy by Watts et al. 2017, in a qualitative
research paper linked to our recent psilocybin for treatment-
resistant depression (TRD) clinical trial (Carhart-Harris et al.
2016)see also (Belser et al. 2017). In 6-month follow-up
interviews, participants were asked: Did this treatment work
for you, and if so how?and responses were analysed for
consistent themes (Watts et al. 2017). Of the 17 patients who
endorsed the treatmentseffectiveness,all made reference to
one particular mediating factor: a renewed sense of connection
or connectedness. This factor was found to have three distin-
guishable aspects: connection to (1) self,(2)others and (3) the
world in general (Watts et al. 2017). For many, the sense of
connectedness featured acutely, during the treatment session
itself, but just as commonly, it endured for several weeks to
months afterwards, as can be seen here from a participant who
remained in remission for 3-months post-treatment:
This connection, its just a lovely feelingthis sense of
connectedness, we are all interconnected.(male, aged
52)
Asenseofdisconnection is a feature of many major psy-
chiatric disorders, particularly depression (Karp 2017), and a
sense of connection or connectedness is considered a key me-
diator of psychological well-being (Cervinka et al. 2012;Lee
et al. 2008), as well as a factor underlying recovery of mental
health (Leamy et al. 2011). One of the most curious aspects of
the growing literature on the therapeutic potential of psyche-
delics is the seeming general nature of their therapeutic appli-
cability (Carhart-Harris and Goodwin 2017), i.e. they have
shown promise not just for the treatment of depression but
for addictions, anxiety and obsessive-compulsive disorder
(Carhart-Harris and Goodwin 2017). This raises the question
of whether psychedelic therapy targets a core factor underly-
ing mental health. We believe that it does, and that
connectedness is the key (Watts et al. 2017).
Like any construct in psychology, connectedness requires
validation work. Validated measures of social connectedness
(Lee and Robbins 1995)andconnectedness to nature
(Mayer and Frantz 2004) already exist. We recently showed
*R. Watts
ros.watts@yahoo.co.uk
1
Psychedelic Research Group, Centre for Psychiatry, Department of
Medicine, Imperial College London, W12 0NN, London, UK
Psychopharmacology
DOI 10.1007/s00213-017-4701-y
that feelings of connectedness to nature are increased post-
psilocybin (Lyons et al. 2017, under review)and see also
(Forstmann and Sagioglou 2017)and correlate with the ex-
tent of past psychedelic drug-use and intensity of ego-disso-
lutionexperienced under a psychedelic (Nour et al. 2017).
There already exist ample behavioural indices of connection
to othersand worldin various guises, and new measures
could be easily devised and developed.
We are presently collecting longitudinal data on social con-
nectedness in individuals who plan a psychedelic experience
and provide web-based survey data on the process. Figure 1
displays some relevant preliminary data from this project,
showing increased social connectedness and psychological
well-being 2 weeks after an experience, plus the significant
positive relationship between them. These data were collected
from a sample of over 200 people. Future work, featuring
mediation modelling could determine whether aspects of the
acute psychedelic experience such as ego-dissolution(Nour
et al. 2016), mystical experience(Barrett et al. 2015)and
awe(Piff et al. 2015) mediate the long-term positive effects
of psychedelics and whether increased connectedness is a
principal component of post-psychedelic therapeutic
changeas we suspect (Watts et al. 2017).
As noted above, connectedness,asitwasdescribedbypa-
tients in our TRD trial, encompassed not just connection to
others (i.e. social connectedness) and the world in general
(e.g. connectedness to nature) but also connection to the self
(Watts et al. 2017). Post-treatment, participants referred to feel-
ing reconnected to past values, pleasures and hobbies as well as
feeling more integrated, embodied and at peace with them-
selves and their often troubled backgrounds. It is a working
hypothesis of ours that connection-to-self is a bedrock from
which connection to others and the world can follow most
naturally. Another hypothesis is that positive therapeutic out-
comes could be jeopardised if the primary connection-to-self
stage is leap-frogged, e.g. due to incomplete psychological
integration (Richards 2015).
Yesterday I was clever, so I wanted to change the world.
Today I am wise, so I am changing myself.(Jalaluddin
Rumi)
Arelevantscaleformeasuringconnection-to-self might be
the quiet ego scale(Wayment et al. 2015). However, we feel
there is much scope for a new connectedness scale that can
incorporate the three sub-factors identified in our recent qual-
itative analysis (Watts et al. 2017), namely connection-to-self,
others and world in general. The scales mentioned above
could serve as tools to test convergent validity; measures of
well-being and psychiatric symptoms could serve as tests of
clinical usefulness and comparator drugs could be incorporat-
ed to test the hypothesis that there is a selective relationship
between psychedelics and connectedness that does not exist
for other psychoactive drugs such as alcohol (chronic and
excessive use especially), stimulants and conventional psychi-
atric medications such as the selective serotonin reuptake in-
hibitors (SSRIs). It is notable in this regard that many patients
in our TRD trial felt that the process and effect of being pre-
scribed conventional treatments merely reinforced their sense
Fig. 1 Measures collected before and 2 weeks after a planned
psychedelic drug experience, as part of a longitudinal web-based survey
project that will be reported on in detail in future publications (https://
www.psychedelicsurvey.com). Well-being was measured with the
Warwick Edinburgh Well-being Scale (Tennant et al. 2007) and scores
range from 14 to 70; social connectedness was measured with the Social
Connectedness Scale (Lee and Robbins 1995) and scores range from 8 to
48. Significant increases in both measures were seen post-psychedelic
(n=204,**p<0.01,pairedttest), and there was a significant positive
relationship between their respective change scores (r=0.387,p<0.01)
Psychopharmacology
of disconnection (Watts et al. 2017). Moreover, stimulant use
has been associated with hubris and individualism and alcohol
use with a lack of concern for nature and the environment
(Nour et al. 2017).
We ar e mindf ul o f the scien ti fical ly d elica te a ssoci at io n
between psychedelics and mystical experience.Despite
previously expressed concerns regarding this construct
(Carhart-Harris and Goodwin 2017), psychedelic-induced
mystical experiences have been found to predict long-
term increases in psychological well-being (Griffiths
et al. 2006) as well as clinical improvements after psyche-
delic therapy (Carhart-Harris and Goodwin 2017). Given
the apparent positive mediational value of such experiences, it
seems pertinent to better understand where their value lies,
and again, we suspect that connectedness may be the key.
Writing in 1960, philosopher Walter Stace referred to the
unitive experience(a sense of onenessor unity)asthe core
hallmark of the mystical experience. Items pertaining to a sense
of onenessform a major part of leading measures of mystical
experience, including the recently validated mystical experi-
ence questionnaire (MEQ)(Barrett et al. 2015). The unitive
experience is closely related to the construct of connectedness.
We re centl y fo un d that sc or esofpsychedelic-inducedunitive
experience correlate highly with scores of ego-dissolution
(Nour et al. 2016). Conceptually, one can consider the ego as
a counter-force to connectedness. Consider for example, an
item from our recently developed ego-inflationmeasure,
scores on which correlated positively with cocaine-use and
negatively with psychedelic-use (Nour et al. 2016): Ifeltmore
important or special than others.Notehowthiscontrastswith
items from the following: (1) our ego-dissolution inventoryor
EDI (Nour et al. 2016): Ifeltfarlessabsorbedbymyown
issues and concerns;(
2) the MEQ: Freedom from the limita-
tions of your personal self and feeling a unity or bond with what
was felt to be greater than your personal self^;(3)theconnect-
edness to nature scale (Mayer and Frantz 2004): Ioftenfeela
sense of oneness with the natural world around meand a
small selfmeasure used in research on awe:Ifeelthepres-
ence of something greater than myself(Piff et al. 2015).
Part of our focus within the Psychedelic Research Group at
Imperial College London has been to better understand the
brain mechanisms of psychedelics, including their putative
therapeutic actions, and while brain imaging adds a perceived
sophistication to psychedelic research, psychological mecha-
nisms are at least as importantoffering a level of explanation
that is closer to the lived-experience, broadly accessible and
also potentially most useful, e.g. in terms of cost-effectively
predicting treatment effectiveness (Carrillo et al. 2017).
Human brain imagings special appeal lies in its ability to
open the black box’—revealing insights about major un-
knownsbut imaging findings can also be misused, e.g. in
terms of excessive reverse inference (Poldrack 2006)and
neuro-realism(Racine et al. 2010). Even so, we recognise
that the healthy demystification process that is presently taking
place in psychedelic research relies in no small part on the
identification of biological substrates of high-level subjective
experiences, and we have no doubt that both an acute and
enduring sense of connectedness have identifiable biological
substrates.
Our work on the neural correlates of ego-dissolutionmay
be considered part of a progressive initiative to demystify the
psychedelic experience (Tagliazucchi et al. 2016;Nouretal.
2016). Like ego-dissolution and entropy(Carhart-Harris
et al. 2014), connectedness is particularly appealing as a con-
struct because it carries meaning in both mechanistic and sub-
jective sense. Our finding of increased global functional con-
nectivity in the psychedelic brainand its relationship to ego-
dissolution (Tagliazucchi et al. 2016) may be considered a
candidate neural correlate of the unitive experiencei.e.
connectedness in its acute form. How this relates to longer-
term feelings of connectedness,however,isperhapsamore
challenging question. Does the unitive experience leave a last-
ing memory trace, analogous to the overview effectexperi-
enced by some astronauts (White 1987)characterised by a
sense of aweand perceived smallness in the presence of
vastness (Piff et al. 2015) or does the psychedelic experiences
cause lasting anatomical and/or functional brain changes?
These possibilities need not be mutually exclusive, and only
properly supported empirical research can advance and even-
tually resolve these matters. We hope that mainstream funding
bodies be broadminded and brave enough to see the possibil-
ities here, as the potential rewards for science and society may
be great.
Finally, it seems remarkable that we can discuss high-level
constructs such as connectednesswhile knowing psyche-
delicsaction at the molecular level. For example, we know
that psychedelics initiate their signature subjective effects via
serotonin 2A-receptor agonism (Carhart-Harris and Nutt
2017). Since psychedelics hijackan existing system, it is
natural to ask what evolutionary role that system has played
throughout our speciesdevelopmentand whether under-
standing this may shed light on our understanding of the func-
tioning of brain serotonin more generally. Relevant questions
have recently been explored (Carhart-Harris and Nutt 2017).
In brief, we have proposed that brain serotonin 2A receptor
signalling mediates a state of rapid plasticity that is conducive
to major change (e.g. in outlook and/or behaviour)when
such change feels necessary (e.g. to aid mental or physical
survival). Such a function may be related to humansunique
capacity for adaptability.
Moving forward, we intend to develop an operational defi-
nition of connectedness that incorporates not just connectedness
in the subjective sense but also its biological basis and various
behavioural manifestations. Crucially, such a definition should
be meaningful and useful not just in the context of psyche-
delicsbut universally.
Psychopharmacology
Acknowledgements RLC-H is supported by the Alex Mosley
Charitable Trust. RW is supported by Compass Pathways.
Author contributions RW conceived of the notion and importance of
connectedness through her follow-up to our recent psilocybin for TRD
trial. RCH wrote this paper with feedback from RW, DE and MK. MK
and EH provided the data for Fig. 1, and EH made the figure. DE pro-
vided intellectual input regarding the central construct plus editorial ad-
vice. All authors read and approved the final manuscript.
Compliance with ethical standards
Conflicts of interest The authors declare that they have no conflicts of
interest.
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Psychopharmacology
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The psychedelic experience (including psychedelic-induced ego dissolution) can effect lasting change in a person's attitudes and beliefs. Here, we aimed to investigate the association between naturalistic psychedelic use and personality, political perspectives, and nature relatedness using an anonymous internet survey. Participants (N = 893) provided information about their naturalistic psychedelic, cocaine, and alcohol use, and answered questions relating to personality traits of openness and conscientiousness (Ten-Item Personality Inventory), nature relatedness (Nature-Relatedness Scale), and political attitudes (one-item liberalism-conservatism measure and five-item libertarian-authoritarian measure). Participants also rated the degree of ego dissolution experienced during their "most intense" recalled psychedelic experience (Ego-Dissolution Inventory). Multivariate linear regression analysis indicated that lifetime psychedelic use (but not lifetime cocaine use or weekly alcohol consumption) positively predicted liberal political views, openness and nature relatedness, and negatively predicted authoritarian political views, after accounting for potential confounding variables. Ego dissolution experienced during a participant's "most intense" psychedelic experience positively predicted liberal political views, openness and nature relatedness, and negatively predicted authoritarian political views. Further work is needed to investigate the nature of the relationship between the peak psychedelic experience and openness to new experiences, egalitarian political views, and concern for the environment.