lecture 5 - Psychedelic drugs Flashcards
classic Psychedelics
LSD (lysergic acid diethylamide; made from lysergic acid found in rye ergot fungus)
- Psilocybin (found in ‘magic mushrooms’)
definitions
-psychedelic
-hallucinogen
-psychotomimetic
Psychedelic = ‘mind revealing’ . A type of drug that changes a persons perception of reality
- Hallucinogen = ‘causing hallucinations’
— psychedelics can cause hallucinations; more often, they cause distortions of perception - Psychotomimetic = ‘mimicking psychosis’
— they can trigger (new) or increase (existing) psychotic effects
(hallucinations, delusions)
— these effects can persist long-term
acute subjective affects of psychedelics
-effects the person taking them will notice
altered perception - increased vividness of colours; distortions
of apparent size of objects; synaesthesia (sensory cross over - read a word and have a certain flavour associate with it) ; illusions of movement; hallucinations, ranging from simple geometric patterns to complex images of objects & people
- Subjectively pleasant effects – incl. ‘loss of self’: feelings of ‘boundlessness’, ‘undifferentiated unity’; altered sense of time &
space; often described in mystical or religious terms - Subjectively unpleasant effects – incl. ‘loss of self’: ‘anxious ego
dissolution’ – frightening feelings of ‘depersonalization’ & ‘derealization’; ideas of reference & paranoia; fear, panic & dangerous behaviour
what is the mechanism for psychedelic effect
-how do they work according to structure (what is a shared structure)
indole ring structure
mechanism for psychedelic effect
-what does the shared indole ring structure suggest
Suggests psychedelic effects involve serotonin (5-HT) receptors, but…:
– simply increasing 5-HT activity throughout the brain (e.g., with
SSRI) doesn’t produce similar effects,
– and neither does simply reducing 5-HT activity (e.g., using ATD).
does increasing / decreasing 5HT activity (by ssris) produce similar results to psychedelics
simply increasing 5-HT activity throughout the brain (e.g., with
SSRI) doesn’t produce similar effects,
– and neither does simply reducing 5-HT activity (e.g., using ATD)
how many types of 5HT receptor is there
At least 14 distinct sub-types of serotonin (5-HT) receptor
Psychedelic drugs are 5HT ______ , but only for some 5HT receptor types (and could be antagonists for others)
Psychedelic drugs are 5-HT agonists, but only for some 5-HT
receptor types (& could be antagonists at others)
-they mimic the effects of serotonin
-these drugs interreact with serotonin receptors in a selective manner
what is the main site of agonistic action for 5HT 2A receptors
-explain how the disruption of these sites could be the bases for ‘psychedelic’ experiences
5-HT 2A receptors in prefrontal cortex & thalamus are main site of
agonistic action
-PFC = high-level cognition, conceptual thinking, sense of self
– thalamus = sensory ‘relay station’, with inputs from sense organs & outputs to sensory cortex
so,,Disruption of these systems could be basis for ‘psychedelic’
experiences (disrupted sense of self, alterations in perception,
synaesthesia
neural correlates of the psychedelic state
-what does psilocybin do to cortical and sub cortical brain areas
Psilocybin (v. placebo) significantly decreased neural activity
in a number of cortical (e.g. PFC) & sub-cortical (e.g. thalamus)
brain areas.
- Intensity of subjective experience correlated significantly with
observed reductions in neural activity (more intense the more decrease of the brain activity)
imaging studies show that psychedlic drugs do what to
-brain areas
-functional connectivity
imaging studies show that psychedelic drugs:
‒ reduce neural activity in brain areas involved in
maintaining a sense of self (the ‘default mode
network’);
‒ increase functional connectivity between brain areas
that usually don’t communicate much.
- Again, these neurophysiological changes correlate
with subjective intensity of experience
Griffiths et al 2006 study
-effects of a single dose of psilocybin
-who participated
-study design
-placebo?
-acute effects
-expectancy effects?
- a study he carried out to test the effects of a single dose of psilocybin in selected healthy, religious/spiritual volunteers
Volunteers were not general population: highly educated (majority
post-grad); healthy & low risk; religious/spiritual, interest in effects
of drugs & extensive self-reflection opportunity.
Used methylphenidate (stimulant; non-psychedelic) as “active
placebo” in a double-blind, within-subjects design.
- Acute effects of psilocybin (v. methylphenidate): changes in
perception (visual pseudo-hallucinations, synaesthesia) & cognition (sense of meaning, ideas of reference); highly labile mood
(alternating between intense joy, sadness & anxiety) - More participants reported mystical experiences and persisting
positive effects following psilocybin than following methylphenidate - BUT there were effects of methylphenidate too, suggesting
expectancy effects in both groups…
Griffiths et al 2006 study
-effects of a single dose of psilocybin
-after 7 hours
-after 2 months
-after 2 months self reported
- After seven hours, reports of a “complete” mystical experience:
– 61% following psilocybin
– 11% following methylphenidate - After two months, ratings of experience being “among top five
most spiritually significant experiences”:
– 38% following psilocybin
– 8% following methylphenidate - After two months, self-reported “moderate” increase in well-being
/ life satisfaction:
– 50% following psilocybin
– 17% following methylphenidate
Griffiths et al 2006 study
-effects of a single dose of psilocybin
-precautions taken to avoid negative effects
-what negative effects were still observed?
Stringent safety precautions (incl. screening of volunteers; clinician
involvement before, during, after) to avoid/manage potentially
dangerous negative drug effects.
Nevertheless:
– 11/36 volunteers reported strong/extreme fear following psilocybin
(none following methylphenidate); two compared it to being in a
war.
– 6/36 experienced ideas of reference/ paranoid thinking following
psilocybin.
“Blinding” to conditions may have been ineffective.
psychedelics in therapy
-what can the benefit?/ positive effects
Long & controversial history (N.B., LSD & psilocybin remain illegal in UK)
- There are (somewhat inconsistent) reports of possible positive effects for LSD- & psilocybin-assisted
psychotherapy in treating:
– addictions (including alcohol & tobacco),
– obsessive-compulsive disorder, and
– depression & anxiety in patients with life-threatening or terminal illnesses
- Currently very active area of research
