OPEN Foundation

Menu
Search
Close this search box.

Psychology

Functional Connectivity Measures After Psilocybin Inform a Novel Hypothesis of Early Psychosis

October 8, 2012 / Mushrooms / Psilocybin, Neuroscience, Papers, Psychology, Psychotic Disorders, Publications / By / , , , , , ,

Abstract

Psilocybin is a classic psychedelic and a candidate drug model of psychosis. This study measured the effects of psilocybin on resting-state network and thalamocortical functional connectivity (FC) using functional magnetic resonance imaging (fMRI). Fifteen healthy volunteers received intravenous infusions of psilocybin and placebo in 2 task-free resting-state scans. Primary analyses focused on changes in FC between the default-mode- (DMN) and task-positive network (TPN). Spontaneous activity in the DMN is orthogonal to spontaneous activity in the TPN, and it is well known that these networks support very differ -ent functions (ie, the DMN supports introspection, whereas the TPN supports externally focused attention). Here, inde -pendent components and seed-based FC analyses revealed increased DMN-TPN FC and so decreased DMN-TPN orthogonality after psilocybin. Increased DMN-TPN FC has been found in psychosis and meditatory states, which share some phenomenological similarities with the psy -chedelic state. Increased DMN-TPN FC has also been observed in sedation, as has decreased thalamocortical FC, but here we found preserved thalamocortical FC after psi -locybin. Thus, we propose that thalamocortical FC may be related to arousal, whereas DMN-TPN FC is related to the separateness of internally and externally focused states. We suggest that this orthogonality is compromised in early psychosis, explaining similarities between its phenomenol -ogy and that of the psychedelic state and supporting the utility of psilocybin as a model of early psychosis.

Carhart-Harris, R. L., Leech, R., Erritzoe, D., Williams, T. M.,  Stone, J. M.,  Evans, J., …. Nutt, D. J. (2012). Functional Connectivity Measures After Psilocybin Inform a Novel Hypothesis of Early Psychosis. Schizophrenia Bulletin, 39(6), 1343-1351. http://dx.doi.org/10.1093/schbul/sbs117
Link to full text

Personality, Psychopathology, Life Attitudes and Neuropsychological Performance among Ritual Users of Ayahuasca: A Longitudinal Study

August 8, 2012 / Ayahuasca, Neuroscience, Papers, Psychology, Publications / By / , , , , , ,

Abstract

Ayahuasca is an Amazonian psychoactive plant beverage containing the serotonergic 5-HT2A agonist N,N-dimethyltryptamine (DMT) and monoamine oxidase-inhibiting alkaloids (harmine, harmaline and tetrahydroharmine) that render it orally active. Ayahuasca ingestion is a central feature in several Brazilian syncretic churches that have expanded their activities to urban Brazil, Europe and North America. Members of these groups typically ingest ayahuasca at least twice per month. Prior research has shown that acute ayahuasca increases blood flow in prefrontal and temporal brain regions and that it elicits intense modifications in thought processes, perception and emotion. However, regular ayahuasca use does not seem to induce the pattern of addiction-related problems that characterize drugs of abuse. To study the impact of repeated ayahuasca use on general psychological well-being, mental health and cognition, here we assessed personality, psychopathology, life attitudes and neuropsychological performance in regular ayahuasca users (n = 127) and controls (n = 115) at baseline and 1 year later. Controls were actively participating in non-ayahuasca religions. Users showed higher Reward Dependence and Self-Transcendence and lower Harm Avoidance and Self-Directedness. They scored significantly lower on all psychopathology measures, showed better performance on the Stroop test, the Wisconsin Card Sorting Test and the Letter-Number Sequencing task from the WAIS-III, and better scores on the Frontal Systems Behavior Scale. Analysis of life attitudes showed higher scores on the Spiritual Orientation Inventory, the Purpose in Life Test and the Psychosocial Well-Being test. Despite the lower number of participants available at follow-up, overall differences with controls were maintained one year later. In conclusion, we found no evidence of psychological maladjustment, mental health deterioration or cognitive impairment in the ayahuasca-using group.

Bouso, J. C, González, D., Fondevila, S., Cutchet, M., Fernández, X., Barbosa, P. C. R., … Riba, J. (2012). Personality, Psychopathology, Life Attitudes and Neuropsychological Performance among Ritual Users of Ayahuasca: A Longitudinal Study. PLoS ONE 7(8), 1-13.  http://dx.doi.org/10.1371/journal.pone.0042421
Link to full text

Hypotheses regarding the mechanisms of ayahuasca in the treatment of addictions

August 2, 2012 / Ayahuasca, Papers, Psychology, Publications, Substance Use Disorder / By / ,

Abstract

Ayahuasca is a medicinal plant mixture utilized by indigenous peoples throughout the Amazon River basin for healing purposes. The “vine of the soul” or “vine of death,” as it is known in South America, contains a combination of monoamine oxidase inhibitors and N,N-dimethyltryptamine (DMT). When ingested together, these medicines produce profound alterations in consciousness. Increasingly, ayahuasca is being utilized to treat addictions. However, the mechanism of action by which ayahuasca treats addictions remains unclear. We offer four hypotheses to explain possible biochemical, physiological, psychological, and transcendent mechanisms by which ayahuasca may exert its anti-addiction effects.

Liester, M. B., & Prickett, J. I. (2012). Hypotheses regarding the mechanisms of ayahuasca in the treatment of addictions. Journal of psychoactive drugs, 44(3), 200-208. 10.1080/02791072.2012.704590
Link to full text

The NMDA antagonist ketamine and the 5-HT agonist psilocybin produce dissociable effects on structural encoding of emotional face expressions

July 27, 2012 / Anxiety Disorders / PTSD, Depressive Disorders, Ketamine, Mushrooms / Psilocybin, Neuroscience, Papers, Psychology, Publications / By / , , , ,

Abstract

Rationale
Both glutamate and serotonin (5-HT) play a key role in the pathophysiology of emotional biases. Recent studies indicate that the glutamate N-methyl-D-aspartate (NMDA) receptor antagonist ketamine and the 5-HT receptor agonist psilocybin are implicated in emotion processing. However, as yet, no study has systematically compared their contribution to emotional biases.

Objectives
This study used event-related potentials (ERPs) and signal detection theory to compare the effects of the NMDA (via S-ketamine) and 5-HT (via psilocybin) receptor system on non-conscious or conscious emotional face processing biases.

Methods
S-ketamine or psilocybin was administrated to two groups of healthy subjects in a double-blind within-subject placebo-controlled design. We behaviorally assessed objective thresholds for non-conscious discrimination in all drug conditions. Electrophysiological responses to fearful, happy, and neutral faces were subsequently recorded with the face-specific P100 and N170 ERP.

Results
Both S-ketamine and psilocybin impaired the encoding of fearful faces as expressed by a reduced N170 over parieto-occipital brain regions. In contrast, while S-ketamine also impaired the encoding of happy facial expressions, psilocybin had no effect on the N170 in response to happy faces.

Conclusion
This study demonstrates that the NMDA and 5-HT receptor systems differentially contribute to the structural encoding of emotional face expressions as expressed by the N170. These findings suggest that the assessment of early visual evoked responses might allow detecting pharmacologically induced changes in emotional processing biases and thus provides a framework to study the pathophysiology of dysfunctional emotional biases.

Schmidt, A., Kometer, M., Bachmann, R., Seifritz, E., & Vollenweider, F.X. (2012). The NMDA antagonist ketamine and the 5-HT agonist psilocybin produce dissociable effects on structural encoding of emotional face expressions. Psychopharmacology, 225(1), 227-239. http://dx.doi.org/doi:10.1007/s00213-012-2811-0
Link to full text

Research on psychedelic substances

July 6, 2012 / Humanities & Art, LSD, Papers, Psychology, Publications / By / ,

Introduction

The term ‘psychedelic ’ (i.e. mind-manifesting) was coined by Humphrey Osmond to characterize a grou p of substances that are capable of liberating human perception from cultural conditioning, providing an op ening to the transcendent qualities of being human. Osmond claimed that LSD and similar drugs may give people insightful experiences that enable them to better understand themselves and their relationships with the world. Psychedelic substances have the potential to show mindmanifesting properties under appropriate internally and externally supported conditions. They can offer lucid insights into one’s psychological make-up and functioning. They are also capable of inducing a spectrum of inner experiences, sometimes
referred to as ‘religious’ or ‘mystical’. Another commonly used term for these substances is ‘hallucinogens’, although this synonym is viewed as controversial because of the implication that they somehow cause hallucinations, which they do very rarely. Most psychedelic substances produce visual alterations of perceived objects and pseudohallucinations which are understood by the subject to be ‘illusionary’ in character […]
<br />
Brandt, S. D., & Passie, T. (2012). Research on psychedelic substances. Drug testing and analysis, 4(7-8), 539-542. https://dx.doi.org/10.1002/dta.1389
<br />
Link to full text

Health status of ayahuasca users.

July 4, 2012 / Ayahuasca, Papers, Psychology, Publications / By / , , ,

Abstract

Ayahuasca is a psychedelic brew originally used for magico-religious purposes by Amerindian populations of the western Amazon Basin. Throughout the last four decades, the use of ayahuasca spread towards major cities in all regions of Brazil and abroad. This trend has raised concerns that regular use of this N,N-dimethyltryptamine- and harmala-alkaloid-containing tea may lead to mental and physical health problems associated typically with drug abuse. To further elucidate the mental and physical health of ayahuasca users, we conducted a literature search in the international medical PubMed database. Inclusion criteria were evaluation of any related effect of ayahuasca use that occurred after the resolution of acute effects of the brew. Fifteen publications were related to emotional, cognitive, and physical health of ayahuasca users. The accumulated data suggest that ayahuasca use is safe and may even be, under certain conditions, beneficial. However, methodological bias of the reviewed studies might have contributed to the preponderance of beneficial effects and to the few adverse effects reported. The data up to now do not appear to allow for definitive conclusions to be drawn on the effects of ayahuasca use on mental and physical health, but some studies point in the direction of beneficial effects. Additional studies are suggested to provide further clarification.

Barbosa, P. C. R., Mizumoto, S., Bogenschutz, M. P., & Strassman, R. J. (2012). Health status of ayahuasca users. Drug testing and analysis, 4(7-8), 601-609. https://dx.doi.org/10.1002/dta.1383
Link to full text

Serotonergic Hallucinogens and Emerging Targets for Addiction Pharmacotherapies

June 1, 2012 / Mushrooms / Psilocybin, Neuroscience, Papers, Psychology, Publications, Substance Use Disorder / By /

Abstract

• Converging lines of evidence from pharmacologic, electrophysiologic, and behavioral
research in animals strongly suggest that activation of cortical 5-hydroxytryptamine-2A
receptors is the most critical step in initiating a cascade of biological events that accounts
for serotonergic hallucinogen (SH) psychoactive properties.
• Psilocybin produces hyperfrontality with divergent prefrontal–subcortical activation in such
a way as to increase cognitive and affective processing in the context of reduced gating
and reduced focus on external stimulus processing.
• In contrast to all other drugs of abuse, SHs are not considered to be capable of producing
sufficient reinforcing effects to cause dependence (addiction) syndromes.
• Given that SHs increase extracellular glutamate levels and activity in the prefrontal–
limbic circuitry, it is possible that a normalization in functional connectivity in this
network through a glutamate-dependent neuroplastic adaptation could produce an
anti-addictive effect.

Ross, S. (2012). Serotonergic hallucinogens and emerging targets for addiction pharmacotherapies. Psychiatric Clinics of North America, 35(2), 357-374. http://dx.doi.org/10.1016/j.psc.2012.04.002
Link to full text

Genuine and drug-induced synesthesia: a comparison

April 21, 2012 / Papers, Psychology, Publications / By / , , , , ,

Abstract

Despite some principal similarities, there is no systematic comparison between the different types of synesthesia (genuine, acquired and drug-induced). This comprehensive review compares the three principal types of synesthesia and focuses on their phenomenological features and their relation to different etiological models. Implications of this comparison for the validity of the different etiological models are discussed.

Comparison of the three forms of synesthesia show many more differences than similarities. This is in contrast to their representation in the literature, where they are discussed in many respects as being virtually similar. Noteworthy is the much broader spectrum and intensity with the typical drug-induced synesthesias compared to genuine and acquired synesthesias. A major implication of the phenomenological comparison in regard to the etiological models is that genuine and acquired synesthesias point to morphological substrates, while drug-induced synesthesia appears to be based on functional changes of brain activity.

Sinke, C., Halpern, J. H., Zedler, M., Neufeld, J., Emrich, H. M., & Passie, T. (2012). Genuine and drug-induced synesthesia: a comparison. Consciousness and cognition, 21(3), 1419-1434. http://dx.doi.org/10.1016/j.concog.2012.03.009
Link to full text

Lysergic acid diethylamide (LSD) for alcoholism: meta-analysis of randomized controlled trials

March 8, 2012 / LSD, Papers, Psychology, Publications, Substance Use Disorder / By / ,

Abstract

Assessments of lysergic acid diethylamide (LSD) in the treatment of alcoholism have not been based on quantitative meta-analysis. Hence, we performed a meta-analysis of randomized controlled trials in order to evaluate the clinical efficacy of LSD in the treatment of alcoholism. Two reviewers independently extracted the data, pooling the effects using odds ratios (ORs) by a generic inverse variance, random effects model. We identified six eligible trials, including 536 participants. There was evidence for a beneficial effect of LSD on alcohol misuse (OR, 1.96; 95% CI, 1.36–2.84; p = 0.0003). Between-trial heterogeneity for the treatment effects was negligible (I² = 0%). Secondary outcomes, risk of bias and limitations are discussed. A single dose of LSD, in the context of various alcoholism treatment programs, is associated with a decrease in alcohol misuse.

Krebs, T. S., & Johansen, P. Ø. (2012). Lysergic acid diethylamide (LSD) for alcoholism: meta-analysis of randomized controlled trials. Journal of Psychopharmacology, 26(2), 994-1002. http://dx.doi.org/10.1177/0269881112439253
Link to full text

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

March 1, 2012 / Mushrooms / Psilocybin, Papers, Psychology, Publications / By / , , , , , ,

Abstract

Background: Psilocybin is a classic psychedelic drug that has a history of use in psychotherapy. One of the rationales for its use was that it aids emotional insight by lowering psychological defences.

Aims: To test the hypothesis that psilocybin facilitates access to personal memories and emotions by comparing subjective and neural responses to positive autobiographical memories under psilocybin and placebo.

Method: Ten healthy participants received two functional magnetic resonance imaging scans (2 mg intravenous psilocybin v. intravenous saline), separated by approximately 7 days, during which they viewed two different sets of 15 positive autobiographical memory cues. Participants viewed each cue for 6 s and then closed their eyes for 16 s and imagined re-experiencing the event. Activations during this recollection period were compared with an equivalent period of eyes-closed rest. We split the recollection period into an early phase (first 8 s) and a late phase (last 8 s) for analysis.

Results: Robust activations to the memories were seen in limbic and striatal regions in the early phase and the medial prefrontal cortex in the late phase in both conditions (P<0.001, whole brain cluster correction), but there were additional visual and other sensory cortical activations in the late phase under psilocybin that were absent under placebo. Ratings of memory vividness and visual imagery were significantly higher after psilocybin (P<0.05) and there was a significant positive correlation between vividness and subjective well-being at follow-up (P<0.01).

Conclusions: Evidence that psilocybin enhances autobiographical recollection implies that it may be useful in psychotherapy either as a tool to facilitate the recall of salient memories or to reverse negative cognitive biases.

Carhart-Harris, R. L., Leech, R., Williams, T. M., Erritzoe, D., Abbasi, N., Bargiotas, T., … & Wise, R. G. (2012). Implications for psychedelic-assisted psychotherapy: functional magnetic resonance imaging study with psilocybin. The British Journal of Psychiatry, 200(3), 238-244. http://dx.doi.org/10.1192/bjp.bp.111.103309
Link to full text

Online Event - Psychedelic Care in Recreational Settings - 3 October 2024

REGISTER NOW
X

interested in becoming a trained psychedelic-assisted therapist?