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Psychology

Psilocybin – Summary of knowledge and new perspectives

December 17, 2013 / Anxiety Disorders / PTSD, Depressive Disorders, Headache Pain and Neurological Disorders, Mushrooms / Psilocybin, Neuroscience, Papers, Pharmacology & Chemistry, Psychology, Psychotic Disorders, Publications, Substance Use Disorder / By / , ,

Abstract

Psilocybin, a psychoactive alkaloid contained in hallucinogenic mushrooms, is nowadays given a lot of attention in the scientific community as a research tool for modeling psychosis as well as due to its potential therapeutic effects. However, it is also a very popular and frequently abused natural hallucinogen. This review summarizes all the past and recent knowledge on psilocybin. It briefly deals with its history, discusses the pharmacokinetics and pharmacodynamics, and compares its action in humans and animals. It attempts to describe the mechanism of psychedelic effects and objectify its action using modern imaging and psychometric methods. Finally, it describes its therapeutic and abuse potential.

Tylš, F., Páleníček, T., & Horáček, J. (2014). Psilocybin – Summary of knowledge and new perspectives. European Neuropsychopharmacology, 24, 342-365. http://dx.doi.org/10.1016/j.euroneuro.2013.12.006

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Ibogaine: a review

December 4, 2013 / Anthropology & Sociology, Biology & Ethnobotany, Iboga / Ibogaine, Papers, Pharmacology & Chemistry, Psychology, Publications, Substance Use Disorder / By /

Publisher Summary

The chapter discusses ibogaine, which is a naturally occurring plant alkaloid with a history of use as a medicinal and ceremonial agent in West Central Africa and has been alleged to be effective in the treatment of drug abuse. The National Institute on Drug Abuse (NIDA) has given significant support to animal research, and the U.S. Food and Drug Administration (FDA) has approved Phase I studies in humans. The chapter discusses the first International Conference on Ibogaine. A major focus of the Conference was the possible mechanism(s) of action of ibogaine. Another important focus of the Conference was to discuss human experience with ibogaine and preclinical and clinical evidence of efficacy and safety. The Conference also featured presentations related to the sociological and anthropological aspects of the sacramental context of the use of iboga in Africa and the distinctive ibogaine subculture of the U.S and Europe. Ibogaine is the most abundant alkaloid in the root bark of the Apocynaceous shrub Tabernanthe iboga, which grows in West Central Africa. The chapter presents a timeline that outlines the historical events relating to the development of ibogaine as a treatment for drug dependence. Ibogaine and serotonin both contain an indole ring in their structure, and ibogaine has been shown to bind to the serotonin transporter and to increase serotonin levels in the nucleus accumbens (NAc). Stereotypy is a methodologic issue that might explain some of the disparate results regarding ibogaine’s interaction with the locomotor response to cocaine.

Alper, K. R. (2001). Ibogaine: a review. The alkaloids: Chemistry and Biology, 56, 1-38. http://dx.doi.org/10.1016/S0099-9598(01)56005-8
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Dimethyltryptamine (DMT): Prevalence, user characteristics and abuse liability in a large global sample

November 27, 2013 / DMT, Papers, Psychology, Publications, Substance Use Disorder / By / , ,

Abstract

This paper presents original research on prevalence, user characteristics and effect profile of N,N-dimethyltryptamine (DMT), a potent hallucinogenic which acts primarily through the serotonergic system. Data were obtained from the Global Drug Survey (an anonymous online survey of people, many of whom have used drugs) conducted between November and December 2012 with 22,289 responses. Lifetime prevalence of DMT use was 8.9% (n=1980) and past year prevalence use was 5.0% (n=1123). We explored the effect profile of DMT in 472 participants who identified DMT as the last new drug they had tried for the first time and compared it with ratings provided by other respondents on psilocybin (magic mushrooms), LSD and ketamine. DMT was most often smoked and offered a strong, intense, short-lived psychedelic high with relatively few negative effects or “come down”. It had a larger proportion of new users compared with the other substances (24%), suggesting its popularity may increase. Overall, DMT seems to have a very desirable effect profile indicating a high abuse liability that maybe offset by a low urge to use more.

Winstock, A. R., Kaar, S., & Borschmann, R. (2013). Dimethyltryptamine (DMT): Prevalence, user characteristics and abuse liability in a large global sample. Journal of Psychopharmacology, 28(1), 49.54. https://dx.doi.org/10.1177/0269881113513852

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Reviewing the ketamine model for schizophrenia

November 20, 2013 / Ketamine, Neuroscience, Papers, Psychology, Psychotic Disorders, Publications / By / ,

Abstract

The observation that antagonists of the N-methyl-D-aspartate receptor (NMDAR), such as phencyclidine (PCP) and ketamine, transiently induce symptoms of acute schizophrenia had led to a paradigm shift from dopaminergic to glutamatergic dysfunction in pharmacological models of schizophrenia. The glutamate hypothesis can explain negative and cognitive symptoms of schizophrenia better than the dopamine hypothesis, and has the potential to explain dopamine dysfunction itself. The pharmacological and psychomimetic effects of ketamine, which is safer for human subjects than phencyclidine, are herein reviewed. Ketamine binds to a variety of receptors, but principally acts at the NMDAR, and convergent genetic and molecular evidence point to NMDAR hypofunction in schizophrenia. Furthermore, NMDAR hypofunction can explain connectional and oscillatory abnormalities in schizophrenia in terms of both weakened excitation of inhibitory γ-aminobutyric acidergic (GABAergic) interneurons that synchronize cortical networks and disinhibition of principal cells. Individuals with prenatal NMDAR aberrations might experience the onset of schizophrenia towards the completion of synaptic pruning in adolescence, when network connectivity drops below a critical value. We conclude that ketamine challenge is useful for studying the positive, negative, and cognitive symptoms, dopaminergic and GABAergic dysfunction, age of onset, functional dysconnectivity,and abnormal cortical oscillations observed in acute schizophrenia.

Frohlich, J., & van Horn, J. D. (2014). Reviewing the ketamine model for schizophrenia. Journal of Psychopharmacology, 28(4), 287-302. http://dx.doi.org/10.1177/0269881113512909
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Ketamine as the prototype glutamatergic antidepressant: pharmacodynamic actions, and a systematic review and meta-analysis of efficacy

October 22, 2013 / Depressive Disorders, Ketamine, Papers, Psychology, Publications / By / , , , ,

Abstract

The burden of depressive disorders and the frequent inadequacy of their current pharmacological treatments are well established. The anaesthetic and hallucinogenic drug ketamine has provoked much interest over the past decade or so as an extremely rapidly acting antidepressant that does not modify ‘classical’ monoaminergic receptors. Current evidence has shown several ways through which it might exert therapeutic antidepressant actions: blockade of glutamatergic NMDA receptors and relative upregulation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) subtypes may alter cortical connectivity patterns; through intracellular changes in protein expression, including the proteins mammalian target of rapamycin (mTOR) and brain-derived neurotrophic factor (BDNF); and alteration of intracellular signalling cascades. The clinical evidence demonstrates rapid improvements in mood and suicidal thinking in most participants, although study numbers have generally been small and many trials are unblinded and methodologically weak. There is a small body of work to suggest ketamine might also augment electroconvulsive therapy and potentially have a role as a surgical anaesthetic in depressed patients. A major problem is that the effects of ketamine appear temporary, disappearing after days to weeks (although longer benefits have been sustained in some), and attempts to circumvent this through pharmacological augmentation have been disappointing thus far. These exciting data are providing new insights into neurobiological models of depression, and potentially opening up a new class of antidepressants, but there are significant practical and ethical issues about any future mainstream clinical role it might have.

Caddy, C., Giaroli, G., White, T. P., Sukhwinder, S. S. & Tracy, D. K. (2014). Ketamine as the prototype glutamatergic antidepressant: pharmacodynamic actions, and a systematic review and meta-analysis of efficacy. Therapeutic Advances in Psychopharmacology, 4(2), 75-79. http://dx.doi.org/10.1177/2045125313507739
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Serotonergic hyperactivity as a potential factor in developmental, acquired and drug-induced synesthesia

October 21, 2013 / LSD, Mescaline / Cacti, Mushrooms / Psilocybin, Neuroscience, Papers, Psychology, Publications / By /

Abstract

Though synesthesia research has seen a huge growth in recent decades, and tremendous progress has been made in terms of understanding the mechanism and cause of synesthesia, we are still left mostly in the dark when it comes to the mechanistic commonalities (if any) among developmental, acquired and drug-induced synesthesia. We know that many forms of synesthesia involve aberrant structural or functional brain connectivity. Proposed mechanisms include direct projection and disinhibited feedback mechanisms, in which information from two otherwise structurally or functionally separate brain regions mix. We also know that synesthesia sometimes runs in families. However, it is unclear what causes its onset. Studies of psychedelic drugs, such as psilocybin, LSD and mescaline, reveal that exposure to these drugs can induce synesthesia. One neurotransmitter suspected to be central to the perceptual changes is serotonin. Excessive serotonin in the brain may cause many of the characteristics of psychedelic intoxication. Excessive serotonin levels may also play a role in synesthesia acquired after brain injury. In brain injury sudden cell death floods local brain regions with serotonin and glutamate. This neurotransmitter flooding could perhaps result in unusual feature binding. Finally, developmental synesthesia that occurs in individuals with autism may be a result of alterations in the serotonergic system, leading to a blockage of regular gating mechanisms. I conclude on these grounds that one commonality among at least some cases of acquired, developmental and drug-induced synesthesia may be the presence of excessive levels of serotonin, which increases the excitability and connectedness of sensory brain regions.

Brogaard, B. (2013). Serotonergic hyperactivity as a potential factor in developmental, acquired and drug-induced synesthesia. Frontiers in Human Neuroscience, 7, 1-13. http://dx.doi.org/10.3389/fnhum.2013.00657
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The induction of synaesthesia with chemical agents: a systematic review

October 17, 2013 / Ayahuasca, DMT, Iboga / Ibogaine, Ketamine, LSD, MDMA, Mescaline / Cacti, Mushrooms / Psilocybin, Papers, Psychology, Publications, Salvia / Salvinorin A / By / ,

Abstract

Despite the general consensus that synaesthesia emerges at an early developmental stage and is only rarely acquired during adulthood, the transient induction of synaesthesia with chemical agents has been frequently reported in research on different psychoactive substances. Nevertheless, these effects remain poorly understood and have not been systematically incorporated. Here we review the known published studies in which chemical agents were observed to elicit synaesthesia. Across studies there is consistent evidence that serotonin agonists elicit transient experiences of synaesthesia. Despite convergent results across studies, studies investigating the induction of synaesthesia with chemical agents have numerous methodological limitations and little experimental research has been conducted. Cumulatively, these studies implicate the serotonergic system in synaesthesia and have implications for the neurochemical mechanisms underlying this phenomenon but methodological limitations in this research area preclude making firm conclusions regarding whether chemical agents can induce genuine synaesthesia.

Luke, D. P., & Terhune, D. B. (2013). The induction of synaesthesia with chemical agents: a systematic review. Frontiers in Psychology, 4, 1-11. http://dx.doi.org/10.3389/fpsyg.2013.00753
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Pharmacological enhancement of exposure-based treatment in PTSD: a qualitative review

October 17, 2013 / Anxiety Disorders / PTSD, MDMA, Papers, Psychology, Publications / By / , ,

Abstract

There is a good amount of evidence that exposure therapy is an effective treatment for posttraumatic stress disorder (PTSD). Notwithstanding its efficacy, there is room for improvement, since a large proportion of patients does not benefit from treatment. Recently, an interesting new direction in the improvement of exposure therapy efficacy for PTSD emerged. Basic research found evidence of the pharmacological enhancement of the underlying learning and memory processes of exposure therapy. The current review aims to give an overview of clinical studies on pharmacological enhancement of exposure-based treatment for PTSD. The working mechanisms, efficacy studies in PTSD patients, and clinical utility of four different pharmacological enhancers will be discussed: d-cycloserine, MDMA, hydrocortisone, and propranolol.

de Kleine, R. A., Rothbaum, B. O., & van Minnen, A. (2013). Pharmacological enhancement of exposure-based treatment in PTSD: a qualitative review. European Journal of Psychotraumatoly, 17(4), 1-15. http://dx.doi.org/10.3402/ejpt.v4i0.21626
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MDMA enhances emotional empathy and prosocial behavior

October 4, 2013 / Anxiety Disorders / PTSD, MDMA, Neuroscience, Papers, Psychology, Publications / By / , , , , , ,

Abstract

3,4-Methylenedioxymethamphetamine (MDMA, ‘ecstasy’) releases serotonin and norepinephrine. MDMA is reported to produce empathogenic and prosocial feelings. It is unknown whether MDMA in fact alters empathic concern and prosocial behavior. We investigated the acute effects of MDMA using the Multifaceted Empathy Test (MET), dynamic Face Emotion Recognition Task (FERT) and Social Value Orientation (SVO) test. We also assessed effects of MDMA on plasma levels of hormones involved in social behavior using a placebo-controlled, double-blind, random-order, cross-over design in 32 healthy volunteers (16 women). MDMA enhanced explicit and implicit emotional empathy in the MET and increased prosocial behavior in the SVO test in men. MDMA did not alter cognitive empathy in the MET but impaired the identification of negative emotions, including fearful, angry and sad faces, in the FERT, particularly in women. MDMA increased plasma levels of cortisol and prolactin, which are markers of serotonergic and noradrenergic activity, and of oxytocin, which has been associated with prosocial behavior. In summary, MDMA sex-specifically altered the recognition of emotions, emotional empathy and prosociality. These effects likely enhance sociability when MDMA is used recreationally and may be useful when MDMA is administered in conjunction with psychotherapy in patients with social dysfunction or post-traumatic stress disorder.

Hysek, C. M., Schmid, Y., Simmler, L. D., Domes, G., Heinrichs, M., Eisenegger, C., … Liechti, M. E. (2013). MDMA enhances emotional empathy and prosocial behavior. Social Cognitive & Affective Neuroscience, 9(11), 1645-1652. http://dx.doi.org/10.1093/scan/nst161
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Effective interventions in the problematic use of alcohol and other drugs

October 1, 2013 / LSD, Papers, Psychology, Publications, Substance Use Disorder / By / , , , ,

Abstract

OBJECTIVE:
Synthesize and assess the available scientific evidence from the period 2008-2012 on interventions of demonstrated efficacy in the treatment and rehabilitation of adolescents and adults engaged in the problematic use of alcohol and other substances.

METHODS:
A systematic review was undertaken with search and analysis of national and international literature on the subject in Spanish and English in the main international databases: PubMed/MEDLINE, LILACS, Embase, PsycINFO, SciELO, the databases of the York University Centre for Reviews and Dissemination (DARE, ETS Database), the Cochrane Library, and other sources of gray literature. The search criteria included randomized clinical trials and systematic reviews but excluded observational studies, qualitative studies, and articles of poor methodological quality.

RESULTS:
The final sample consisted of 69 studies. The psychosocial interventions shown to be effective were cognitive behavioral therapy, family interventions, self-help interventions using the Internet, couples behavioral therapy, community strengthening and family training, telephone monitoring and support, and integrated therapy for substance abuse disorder with anxiety and depression comorbidity. Pharmacological interventions of demonstrated effectiveness were acamprosate, lysergic acid diethylamide (LSD), and benzodiazepines in problematic alcohol use, as well as maintenance therapy with high-dose opioids.

CONCLUSIONS:
The demonstrated effectiveness of psychosocial and pharmacological interventions is slight but significant. However, strongly multidisciplinary interventions that use a cognitive behavioral approach and the involvement of people close to the consumer, as well as some of the specific pharmacological interventions, have been shown to yield the best results in terms of indicators of abstinence and prevention of relapses.

Lefio L. Á., Villarroel S.R., Rebolledo C., Zamorano P., & Rivas K. (2013). Effective interventions in the problematic use of alcohol and other drugs. Revista Panamericana de Salud Pública, 34(4), 257-266.
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