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Anxiety Disorders / PTSD

Prophylactic Ketamine Attenuates Learned Fear

January 27, 2017 / Anxiety Disorders / PTSD, Depressive Disorders, Ketamine, Neuroscience, Papers, Psychology, Publications / By / , , , , , ,

Abstract

Ketamine has been reported to be an efficacious antidepressant for major depressive disorder (MDD) and posttraumatic stress disorder (PTSD). Most recently, ketamine has also been shown to be prophylactic against stress-induced depressive-like behavior in mice. It remains unknown, however, when ketamine should be administered relative to a stressor in order to maximize its antidepressant and/or prophylactic effects. Moreover, it is unknown if ketamine can be prophylactic against subsequent stressors. We systematically administered ketamine at different time points relative to a fear experience in order to determine when ketamine is most effective at reducing fear expression or preventing fear reactivation. Using a contextual fear conditioning (CFC) paradigm, mice were administered a single dose of saline or ketamine (30 mg kg−1) at varying time points before or after CFC. Mice administered prophylactic ketamine 1 week, but not 1 month or 1 h before CFC, exhibited reduced freezing behavior when compared with mice administered saline. In contrast, ketamine administration following CFC or during extinction did not alter subsequent fear expression. However, ketamine administered before reinstatement increased the number of rearing bouts in an open field, possibly suggesting an increase in attentiveness. These data indicate that ketamine can buffer a fear response when given a week before as prophylactic, but not when given immediately before or after a stress-inducing episode. Thus, ketamine may be most useful in the clinic if administered in a prophylactic fashion 1 week before a stressor in order to protect against heightened fear responses to aversive stimuli.

McGowan, J. C., LaGamma, C. T., Lim, S. C., Tsitsiklis, M., Neria, Y., Brachman, R. A., & Denny, C. A. (2017). Prophylactic Ketamine Attenuates Learned Fear. Neuropsychopharmacology. 10.1038/npp.2017.19
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Clinical potential of psilocybin as a treatment for mental health conditions

January 1, 2017 / Anxiety Disorders / PTSD, Depressive Disorders, Mushrooms / Psilocybin, Papers, Psychology, Publications, Substance Use Disorder / By / ,

Abstract

Psilocybin, a classic hallucinogen, is a chemical produced by more than 100 species of mushrooms worldwide. It has high affinity for several serotonin receptors, including 5-HT1A, 5-HT2A, and 5-HT2C, located in numerous areas of the brain, including the cerebral cortex and thalamus. With legislation introduced in 1992, more work is being done to further understand the implications of psilocybin use in a number of disease states. Certain mental health disease states and symptoms have been studied, including depressed mood, anxiety disorders, obsessive-compulsive disorder, alcohol use disorder, and tobacco use disorder. This article provides an in-depth review of the study design and results of psilocybin in each of these conditions and discusses the clinical potential for use.

Daniel, J., & Haberman, M. (2017). Clinical potential of psilocybin as a treatment for mental health conditions. Mental Health Clinician, 7(1), 24-28. 10.9740/mhc.2017.01.024

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Ketamine accelerates fear extinction via mTORC1 signaling

December 30, 2016 / Anxiety Disorders / PTSD, Ketamine, Neuroscience, Papers, Psychology, Publications / By / , , , ,

Abstract

Impaired fear extinction contributes to the persistence of post-traumatic stress disorder (PTSD), and can be utilized for the study of novel therapeutic agents. Glutamate plays an important role in the formation of traumatic memories, and in the pathophysiology and treatment of PTSD, highlighting several possible drug targets. Recent clinical studies demonstrate that infusion of ketamine, a glutamate NMDA receptor antagonist, rapidly and significantly reduces symptom severity in PTSD patients. In the present study, we examine the mechanisms underlying the actions of ketamine in a rodent model of fear conditioning, extinction, and renewal. Rats received ketamine or saline 24 h after fear conditioning and were then subjected to extinction-training on each of the following three days. Ketamine administration enhanced extinction on the second day of training (i.e., reduced freezing behavior to cue) and produced a long-lasting reduction in freezing on exposure to cue plus context 8 days later. Additionally, ketamine and extinction exposure increased levels of mTORC1 in the medial prefrontal cortex (mPFC), a region involved in the acquisition and retrieval of extinction, and infusion of the selective mTORC1 inhibitor rapamycin into the mPFC blocked the effects of ketamine on extinction. Ketamine plus extinction also increased cFos in the mPFC and administration of a glutamate-AMPA receptor antagonist blocked the effects of ketamine. These results support the hypothesis that ketamine produces long-lasting mTORC1/protein synthesis and activity dependent effects on neuronal circuits that enhance the expression of extinction and could represent a novel approach for the treatment of PTSD.

Girgenti, M. J., Ghosal, S., LoPresto, D., Taylor, J. R., & Duman, R. S. (2017). Ketamine accelerates fear extinction via mTORC1 signaling. Neurobiology of Disease, 100, 1-8. 10.1016/j.nbd.2016.12.026
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Psilocybin: promising results in double-blind trials require confirmation by real-world evidence

December 6, 2016 / Anxiety Disorders / PTSD, Depressive Disorders, Mushrooms / Psilocybin, Papers, Psychology, Publications / By / ,

Breckenridge, A., & Grobbee, D. E. (2016). Psilocybin: promising results in double-blind trials require confirmation by real-world evidence. Journal of psychopharmacology (Oxford, England), 30(12), 1218. 10.1177/0269881116675784
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Psilocybin for depression and anxiety associated with life-threatening illnesses

December 6, 2016 / Anxiety Disorders / PTSD, Depressive Disorders, Mushrooms / Psilocybin, Papers, Psychology, Publications / By / , ,

Abstract

Life-threatening and terminal illnesses are accompanied by substantial stressors that encumber both patients and their families. Faced with a life-threatening diagnosis such as late-stage cancer, these factors can compound the existential crisis of impending mortality and produce or exacerbate major depressive and anxiety symptoms (Silverstone, 1990; Vergo et al., 2016). Addressing depression and anxiety in the unique context of life-threatening illnesses has been a significant problem for palliative psychiatric care. In this regard, two recent studies suggest that the one-time use of the naturally derived psychoactive compound psilocybin could have the potential to alleviate these symptoms for up to six months.

McCorvy, J. D., Olsen, R. H., & Roth, B. L. (2016). Psilocybin for depression and anxiety associated with life-threatening illnesses. Journal of psychopharmacology (Oxford, England), 30(12), 1209. 10.1177/0269881116675771
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The role of psychedelics in palliative care reconsidered: A case for psilocybin

December 1, 2016 / Anxiety Disorders / PTSD, Mushrooms / Psilocybin, Papers, Psychology, Publications / By / , , , ,

Kelmendi, B., Corlett, P., Ranganathan, M., D’Souza, C., & Krystal, J. H. (2016). The role of psychedelics in palliative care reconsidered: A case for psilocybin. Journal of psychopharmacology (Oxford, England), 30(12), 1212. 10.1177/0269881116675781
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