Implications for psychedelic-assisted psychotherapy: a functional magnetic resonance imaging study with psilocybin

03/01/2012

in BF Scientific Publications,Psilocybin,Research

 Carhart-Harris RL,  Feilding A, Wise RG, Nutt DJ et al. British Journal of Psychiatry, 2012, 200(3):238–44.

This study, carried out as part of the Beckley-Imperial Psychedelic Research Programme, aimed to investigate the hypothesis that psilocybin facilitates access to personal memories and emotions by comparing the subjective and neural response to positive autobiographical memory recollection under psilocybin versus placebo. [1]

(See below for METHOD)

FINDINGS and IMPLICATIONS

  • Under psilocybin greater activations were seen in sensory cortical regions in the late phase of memory recollection. Under placebo, these regions showed deactivations.
  • Participants rated the memories as more vivid and visual under psilocybin.
It seems likely that the increased sensory cortex activation is linked to the increased visual imagery and vividness of recall under psilocybin. Increased activation during recall under psilocybin contrasts interestingly with its association with [deactivation in the resting state][2]. One theory to link these together is that the areas deactivated under psilocybin are crucial for controlling and integrating activity across the brain (the ‘default mode network'[3]). While these hub areas are unable to exert their influence, activity associated with sensory input or carrying out tasks will be less moderated [2].

 

  • Late phase right parahippocampal activations correlated positively with how emotional the memories were.
  • In a follow-up study the vividness of the memories correlated positively with their later subjective wellbeing.
The emotional positivity associated with the psychedelic experience, and its persistence, have been well documented previously by Griffiths et al. (2008). This study also suggests that psilocybin/the psychedelic experience may be useful as an aid to psychotherapy, either as a way to facilitate the recall of salient memories or in facilitating the development of positive cognitive/emotional biases as in cognitive behavioural therapy for depression.
FUTURE DIRECTIONS
The work carried out in this programme, and this study in particular – represent crucial pilot studies
The results of this and our other psilocybin research at Imperial have resulting in a grant of £550,000 from the Medical Research Council in order to investigate the potential efficacy of psilocybin in treating depression.
 METHOD
  • 15 healthy participants recollected positive autobiographical memories under the influence of psilocybin or placebo during fMRI scanning.
  • The two scanning sessions were carried out in balanced order (some participants received placebo first, others psilocybin) and separated by approximately seven days.
  • The participants were asked to generate at least 30 personal memories of specific positive autobiographical events. They were also asked to generate a cue sentence to prompt recall of each memory (which they were free to encrypt or code to keep confidential). Lastly, participants estimated their age when each recollected event took place, and rated the emotional potency of the memory.
  • Using this information, the memories were split into two sets of 15, balanced for recency and potency, and then randomly assigned to either the psilocybin or placebo conditions for each participant.
  • Psilocybin or placebo was administered intravenously. In the case of psilocybin, this ensures that a small dose rapidly induces its subjective and neural effects.
  • 3 different conditions were repeated 15 times in the same order during both scanning sessions:
    • Rest: Auditory tone followed by visual instruction ‘relax’ (presented for 6 seconds) then ‘close your eyes’. Another auditory tone 16s later signalled for participants to open their eyes. This gave an unbiased baseline, matched for sensory input (i.e. eyes closed) to compare recollection to.
    • Memory task: A memory cue sentence was presented (6s) before the instruction ‘close your eyes’. 16s was given for participants to recollect before another auditory tone, signalling for them to open their eyes.
    • Attention task: Visual instruction to ‘count the beeps’ (6s) followed by ‘close your eyes’ and onset of attention task (16s). The chosen task was a sequence of auditory tones of different pitch playing in left or right ear, with one extra tone in either left or right – participants had to identify which ear heard more tones. This task prevents carry over effects from memory trials into rest trials, by distracting participants from continued recollection.
  • Memory ratings (0-10 scale) of vividness, emotional intensity, valence and the extent to which the memory elicited visual imagery were given by participants (e.g. ‘How strong was the emotion you felt, with 10 being extremely intense?’) when they exited the scanner.
  • Follow-up ratings in subjective well-being and life satisfaction were taken two weeks later on scale of -3 (decreased very much) to +3 (increased very much) with 0 as ‘no change’.
REFERENCES
[1]Carhart Harris et al. (2012)  Implications for psychedelic-assisted psychotherapy: functional magnetic resonance imaging study with psilocybin British Journal of Psychiatry, 2012, 200(3):238–44.
[2] Carhart-Harris et al (2012) Neural correlates of the psychedelic state as determined by fMRI studies with psilocybin. Proceedings of the National Academy of the Sciences USA. 2012 Feb 7;109(6):2138-43. doi: 10.1073/pnas.1119598109. Epub 2012 Jan 23.
[3] http://en.wikipedia.org/wiki/Default_network / Raichle (2010)  Two views of Brain Function  Trends Cog Sci 2010 Apr; 14(4): 180-190

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