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Psychology

The Psychedelic State Induced by Ayahuasca Modulates the Activity and Connectivity of the Default Mode Network

February 18, 2015 / Ayahuasca, Neuroscience, Papers, Psychology, Publications / By / , , , , , ,

Abstract

The experiences induced by psychedelics share a wide variety of subjective features, related to the complex changes in perception and cognition induced by this class of drugs. A remarkable increase in introspection is at the core of these altered states of consciousness. Self-oriented mental activity has been consistently linked to the Default Mode Network (DMN), a set of brain regions more active during rest than during the execution of a goal-directed task. Here we used fMRI technique to inspect the DMN during the psychedelic state induced by Ayahuasca in ten experienced subjects. Ayahuasca is a potion traditionally used by Amazonian Amerindians composed by a mixture of compounds that increase monoaminergic transmission. In particular, we examined whether Ayahuasca changes the activity and connectivity of the DMN and the connection between the DMN and the task-positive network (TPN). Ayahuasca caused a significant decrease in activity through most parts of the DMN, including its most consistent hubs: the Posterior Cingulate Cortex (PCC)/Precuneus and the medial Prefrontal Cortex (mPFC). Functional connectivity within the PCC/Precuneus decreased after Ayahuasca intake. No significant change was observed in the DMN-TPN orthogonality. Altogether, our results support the notion that the altered state of consciousness induced by Ayahuasca, like those induced by psilocybin (another serotonergic psychedelic), meditation and sleep, is linked to the modulation of the activity and the connectivity of the DMN.

Palhano-Fontes, F., Andrade, K. C., Tofoli, L. F., Santos, A. C., Crippa, J., Hallak, J. A., … Araujo, D. B. (2015). The Psychedelic State Induced by Ayahuasca Modulates the Activity and Connectivity of the Default Mode Network. PLoS One. https://dx.doi.org/10.1371/journal.pone.0118143
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The subjective experience of acute, experimentally-induced Salvia divinorum inebriation

February 17, 2015 / Neuroscience, Papers, Psychology, Publications, Salvia / Salvinorin A / By / , , ,

Abstract

This study examined the overall psychological effects of inebriation facilitated by the naturally-occurring plant hallucinogen Salvia divinorum using a double-blind, randomized, placebo-controlled trial. Thirty healthy individuals self-administered Salvia divinorum via combustion and inhalation in a quiet, comfortable research setting. Experimental sessions, post-session interviews, and 8-week follow-up meetings were audio recorded and transcribed to provide the primary qualitative material analyzed here. Additionally, post-session responses to the Hallucinogen Rating Scale provided a quantitative groundwork for mixed-methods discussion. Qualitative data underwent thematic content analysis, being coded independently by three researchers before being collaboratively integrated to provide the final results. Three main themes and 10 subthemes of acute intoxication emerged, encompassing the qualities of the experience, perceptual alterations, and cognitive-affective shifts. The experience was described as having rapid onset and being intense and unique. Participants reported marked changes in auditory, visual, and interoceptive sensory input; losing normal awareness of themselves and their surroundings; and an assortment of delusional phenomena. Additionally, the abuse potential of Salvia divinorum was examined post hoc. These findings are discussed in light of previous research, and provide an initial framework for greater understanding of the subjective effects of Salvia divinorum, an emerging drug of abuse.

Addy, P. H., Garcia-Romeu, A., Metzger, M., & Wade, J. (2015). The subjective experience of acute, experimentally-induced Salvia divinorum inebriation. Journal of Psychopharmacology. https://dx.doi.org/10.1177/0269881115570081
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Regulation of neural responses to emotion perception by ketamine in individuals with treatment-resistant major depressive disorder

February 17, 2015 / Depressive Disorders, Ketamine, Neuroscience, Papers, Psychology, Publications / By / , , , , , ,

Abstract

The glutamate N-methyl-D-aspartate receptor antagonist ketamine has demonstrated antidepressant effects in individuals with treatment-resistant major depressive disorder (TRD) within 24 h of a single dose. The current study utilized functional magnetic resonance imaging (fMRI) and two separate emotion perception tasks to examine the neural effects of ketamine in patients with TRD. One task used happy and neutral facial expressions; the other used sad and neutral facial expressions. Twenty patients with TRD free of concomitant antidepressant medication underwent fMRI at baseline and 24 h following administration of a single intravenous dose of ketamine (0.5 mg kg−1). Adequate data were available for 18 patients for each task. Twenty age- and sex-matched healthy volunteers were scanned at one time point for baseline comparison. Whole-brain, voxel-wise analyses were conducted controlling for a family-wise error rate (FWE) of P<0.05. Compared with healthy volunteers, TRD patients showed reduced neural responses to positive faces within the right caudate. Following ketamine, neural responses to positive faces were selectively increased within a similar region of right caudate. Connectivity analyses showed that greater connectivity of the right caudate during positive emotion perception was associated with improvement in depression severity following ketamine. No main effect of group was observed for the sad faces task. Our results indicate that ketamine specifically enhances neural responses to positive emotion within the right caudate in depressed individuals in a pattern that appears to reverse baseline deficits and that connectivity of this region may be important for the antidepressant effects of ketamine.

Murrough, J. W., Collins, K. A., Fields, J., DeWilde, K. E., Phillips, M. L., Mathew, S. J., … & Iosifescu, D. V. (2015). Regulation of neural responses to emotion perception by ketamine in individuals with treatment-resistant major depressive disorder. Translational psychiatry, 5(2). https://dx.doi.org/10.1038/tp.2015.10
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Neural correlates of change in major depressive disorder anhedonia following open-label ketamine

February 17, 2015 / Depressive Disorders, Ketamine, Neuroscience, Papers, Psychology, Publications / By / , , , , ,

Abstract

Anhedonia is a cardinal symptom of major depression and is often refractory to standard treatment, yet no approved medication for this specific symptom exists. In this exploratory re-analysis, we assessed whether administration of rapid-acting antidepressant ketamine was associated specifically with reduced anhedonia in medication-free treatment-refractory patients with major depressive disorder in an open-label investigation. Additionally, participants received either oral riluzole or placebo daily beginning 4 hours post-infusion. A subgroup of patients underwent fluorodeoxyglucose positron emission tomography scans at baseline (1–3 days pre-infusion) and 2 hours post-ketamine infusion. Anhedonia rapidly decreased following a single ketamine infusion; this was sustained for up to three days, but was not altered by riluzole. Reduced anhedonia correlated with increased glucose metabolism in the hippocampus and dorsal anterior cingulate cortex (dACC) and decreased metabolism in the inferior frontal gyrus and orbitofrontal cortex (OFC). The tentative relationship between change in anhedonia and glucose metabolism remained significant in dACC and OFC, and at trend level in the hippocampus, a result not anticipated, when controlling for change in total depression score. Results, however, remain tenuous due to the lack of a placebo control for ketamine. In addition to alleviating overall depressive symptoms, ketamine could possess anti-anhedonic potential in major depressive disorder, which speculatively, may be mediated by alterations in metabolic activity in the hippocampus, dACC and OFC.

Lally, N., Nugent, A. C., Luckenbaugh, D. A., Niciu, M. J., Roiser, J. P., & Zarate, C. A. (2015). Neural correlates of change in major depressive disorder anhedonia following open-label ketamine. Journal of Psychopharmacology. https://dx.doi.org/10.1177/0269881114568041
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Peak experiences and the afterglow phenomenon: When and how do therapeutic effects of hallucinogens depend on psychedelic experiences?

February 9, 2015 / Anxiety Disorders / PTSD, Depressive Disorders, Headache Pain and Neurological Disorders, Ketamine, LSD, Mescaline / Cacti, Mushrooms / Psilocybin, Neuroscience, Papers, Psychology, Publications, Substance Use Disorder / By / , ,

Abstract

Interest in the therapeutic potential of psychedelic substances has recently resumed. During an early phase of human psychedelic research, their therapeutic application in different pathologies had been suggested, and the first evidence for efficacy was provided. The range of recent clinical applications of psychedelics spans from cluster headaches and obsessive-compulsive disorder to addiction and the treatment of fear and anxiety in patients suffering from terminal illness, indicating potentially different therapeutic mechanisms. A variety of approaches in psychotherapy emphasize subjective experiences, such as so-called peak experiences or afterglow phenomena, as differentially mediating therapeutic action. This review aims to re-evaluate earlier and recent concepts of how psychedelic substances may exert beneficial effects. After a short outline of neurophenomenological aspects, we discuss different approaches to how psychedelics are used in psychotherapy. Finally, we summarize evidence for the relationship between subjective experiences and therapeutic success. While the distinction between pharmacological and psychological action obviously cannot be clear-cut, they do appear to contribute differently from each other when their effects are compared with regard to pathologies.

Majić, T., Schmidt, T. T., & Gallinat, J. (2015). Peak experiences and the afterglow phenomenon: When and how do therapeutic effects of hallucinogens depend on psychedelic experiences? Journal of Psychopharmacology. https://dx.doi.org/10.1177/0269881114568040
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The Effect of Repeated Ketamine Infusion Over Facial Emotion Recognition in Treatment-Resistant Depression: A Preliminary Report

February 6, 2015 / Depressive Disorders, Ketamine, Papers, Psychology, Publications / By / , , , , ,

Abstract

In contrast to improvement in emotion recognition bias by traditional antidepressants, the authors report preliminary findings that changes in facial emotion recognition are not associated with response of depressive symptoms after repeated ketamine infusions or relapse during follow-up in treatment-resistant depression.

Shiroma, P. R., Albott, C. S., Johns, B., Thuras, P., Wels, J., & Lim, K. O. (2015). The Effect of Repeated Ketamine Infusion Over Facial Emotion Recognition in Treatment-Resistant Depression: A Preliminary Report. The Journal of Neuropsychiatry and Clinical Neurosciences. http://dx.doi.org/10.1176/appi.neuropsych.14100243
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New World Tryptamine Hallucinogens and the Neuroscience of Ayahuasca

February 6, 2015 / Ayahuasca, Biology & Ethnobotany, DMT, Mushrooms / Psilocybin, Neuroscience, Papers, Psychology, Publications / By / ,

Abstract

New World indigenous peoples are noted for their sophisticated use of psychedelic plants in shamanic and ethnomedical practices. The use of psychedelic plant preparations among New World tribes is far more prevalent than in the Old World. Yet, although these preparations are botanically diverse, almost all are chemically similar in that their active principles are tryptamine derivatives, either DMT or related constituents. Part 1 of this paper provides an ethnopharmacological overview of the major tryptamine-containing New World hallucinogens.

McKenna, D., & Riba, J. (2015). New World Tryptamine Hallucinogens and the Neuroscience of Ayahuasca. Current Topics in Behavioral Neuroscience. https://dx.doi.org/10.1007/7854_2015_368

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Drug models of schizophrenia

February 5, 2015 / Ketamine, LSD, Mushrooms / Psilocybin, Neuroscience, Papers, Psychology, Psychotic Disorders, Publications, Salvia / Salvinorin A / By / , ,

Abstract

Schizophrenia is a complex mental health disorder with positive, negative and cognitive symptom domains. Approximately one third of patients are resistant to currently available medication. New therapeutic targets and a better understanding of the basic biological processes that drive pathogenesis are needed in order to develop therapies that will improve quality of life for these patients. Several drugs that act on neurotransmitter systems in the brain have been suggested to model aspects of schizophrenia in animals and in man. In this paper, we selectively review findings from dopaminergic, glutamatergic, serotonergic, cannabinoid, GABA, cholinergic and kappa opioid pharmacological drug models to evaluate their similarity to schizophrenia. Understanding the interactions between these different neurotransmitter systems and their relationship with symptoms will be an important step towards building a coherent hypothesis for the pathogenesis of schizophrenia.

Steeds, H., Carhart-Harris, R. L., & Stone, J. M. (2014). Drug models of schizophrenia. Therapeutic Advances in Psychopharmacology. https://dx.doi.org/10.1177/2045125314557797
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Preliminary analysis of positive and negative syndrome scale in ketamine-associated psychosis in comparison with schizophrenia

February 1, 2015 / Ketamine, Neuroscience, Papers, Psychology, Psychotic Disorders, Publications / By / , , , , , ,

Abstract

Objective

Studies of the effects of the N-methyl-d–aspartate (NMDA) glutamate receptor antagonist, ketamine, have suggested similarities to the symptoms of schizophrenia. Our primary goal was to evaluate the dimensions of the Positive and Negative Syndrome Scale (PANSS) in ketamine users (acute and chronic) compared to schizophrenia patients (early and chronic stages).

Method

We conducted exploratory factor analysis for the PANSS from four groups: 135 healthy subject administrated ketamine or saline, 187 inpatients of ketamine abuse; 154 inpatients of early course schizophrenia and 522 inpatients of chronic schizophrenia. Principal component factor analyses were conducted to identify the factor structure of the PANSS.

Results

Factor analysis yielded five factors for each group: positive, negative, cognitive, depressed, excitement or dissociation symptoms. The symptom dimensions in two schizophrenia groups were consistent with the established five-factor model (Wallwork et al., 2012). The factor structures across four groups were similar, with 19 of 30 symptoms loading on the same factor in at least 3 of 4 groups. The factors in the chronic ketamine group were more similar to the factors in the two schizophrenia groups rather than to the factors in the acute ketamine group. Symptom severities were significantly different across the groups (Kruskal–Wallis χ2(4) = 540.6, p < 0.0001). Symptoms in the two ketamine groups were milder than in the two schizophrenia groups (Cohen’s d = 0.7).

Conclusion

Our results provide the evidence of similarity in symptom dimensions between ketamine psychosis and schizophrenia psychosis. The interpretations should be cautious because of potential confounding factors.

Xu, K., Krystal, J. H., Ning, Y., He, H., Wang, D., Ke, X., … & Fan, N. (2015). Preliminary analysis of positive and negative syndrome scale in ketamine-associated psychosis in comparison with schizophrenia. Journal of psychiatric research, 61, 64-72. https://dx.doi.org/doi:10.1016/j.jpsychires.2014.12.012
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Antidepressant actions of ketamine: from molecular mechanisms to clinical practice

February 1, 2015 / Depressive Disorders, Ketamine, Neuroscience, Papers, Psychology, Publications / By / ,

Abstract

In the past decade the emergence of glutamate N-methyl-d-aspartate (NMDA) receptor blockers such as ketamine as fast-acting antidepressants fostered a major conceptual advance by demonstrating the possibility of a rapid antidepressant response. This discovery brings unique mechanistic insight into antidepressant action, as there is a substantial amount of basic knowledge on glutamatergic neurotransmission and how blockade of NMDA receptors may elicit plasticity. The combination of this basic knowledge base and the growing clinical findings will facilitate the development of novel fast acting antidepressants.

Monteggia, L. M., & Zarate, C. (2015). Antidepressant actions of ketamine: from molecular mechanisms to clinical practice. Current opinion in neurobiology, 30, 139-143. https://dx.doi.org/doi:10.1016/j.conb.2014.12.004
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