Concept

Hallucinogen persisting perception disorder

Hallucinogen persisting perception disorder (HPPD) is a non-psychotic disorder in which a person experiences apparent lasting or persistent visual hallucinations or perceptual distortions after a previous use of drugs, including but not limited to psychedelics, dissociatives, entactogens, tetrahydrocannabinol (THC), and SSRIs. Despite being designated as a hallucinogen-specific disorder, the specific contributory role of psychedelic drugs is unknown. The hallucinations and perceptual changes consist of, but are not limited to, visual snow, trails and after images (palinopsia), light fractals on flat surfaces, intensified colors, altered motion perception, pareidolia, micropsia, and macropsia. People who have never previously taken drugs have also reported some symptoms associated with HPPD (such as floaters and visual snow). HPPD is a DSM-5 diagnosis with diagnostic code 292.89 (F16.983). For the diagnosis to be made, other psychological, psychiatric, or neurological conditions must be ruled out and it must cause distress in everyday life. In the ICD-10, the diagnosis code F16.7 corresponds most closely to the clinical picture. HPPD is rarely recognized amongst both hallucinogen users and psychiatrists, and is often misdiagnosed as a substance-induced psychosis. Newer research makes a distinction between HPPD I and HPPD II. The more drastic cases, as seen in HPPD II, are believed to be caused by the use of psychedelics as well as comorbid mental disorders. Some people who have this disorder report that they developed symptoms of HPPD after their first use of such drugs (most notably LSD). Because research regarding HPPD is currently lacking, there is little information on effective treatments, its aetiology and relationship to other disorders, and precise mechanism. In 1898, the English physician and intellectual Havelock Ellis reported a heightened sensitivity to what he described as "the more delicate phenomena of light and shade and color" for a prolonged period of time after he was exposed to the hallucinogenic drug mescaline.

Official source

https://en.wikipedia.org/wiki/Hallucinogen_persisting_perception_disorder

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related lectures (1)

Understanding Parkinson's Disease: Symptoms and Treatments Log in to Mediaspace to watch this video

Explores Parkinson's disease, covering symptoms, treatments, cognitive impairments, and hallucinations.

Graph Chat

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.

Official source

https://en.wikipedia.org/wiki/Hallucinogen_persisting_perception_disorder

About this result

Related lectures (1)

Understanding Parkinson's Disease: Symptoms and Treatments Log in to Mediaspace to watch this video

Explores Parkinson's disease, covering symptoms, treatments, cognitive impairments, and hallucinations.

Related publications (6)

Dopaminergic therapy selectively amplifies hallucination susceptibility in patients with Parkinson's disease with cortico-striatal hyperconnectivity

Dopamine replacement therapy (DRT) alleviates motor symptoms in Parkinson's disease (PD) but can trigger hallucinations in a subset of patients, yet the neural basis of this selective vulnerability is unknown. Hallucinations are among the most disabling non-motor symptoms of PD, linked to social isolation, dementia and institutionalization. Using a validated robotic paradigm to induce and quantify hallucinations in real-time, combined with resting-state fMRI in a crossover On/Off DRT design, we studied pati

openRxiv2026

Modelling Thematic Structure in Clinical Dialogues for Interpretable Depression Detection

Detecting depression from clinical interviews requires models that capture discourse-level thematic structure rather than relying solely on lexical features. We propose Topic-GCN, a heterogeneous graph convolutional network that jointly encodes word, latent topic, and document nodes, enabling explicit modelling of topic–document associations for interview-level classification. The learned topic nodes surface interpretable symptom-relevant clusters whose class-conditional relevance can be mapped to establish

Springer Nature Switzerland2026

Presence Hallucination Induction through Robotically Mediated Somatomotor Conflicts: a pooled analysis of 26 experiments

Hallucinations are significant symptoms in psychiatric and neurodegenerative diseases, that may indicate advanced disease progression or worse disease forms. They are also frequent in healthy individuals, especially elderly or bereaved. Despite their relevance, studying hallucinations in controlled laboratory conditions remains challenging given the limited procedures inducing clinically relevant hallucinations. We have previously developed a robotics-based protocol capable of inducing a specific clinically

bioRxiv2025

Related people (17)

Jevita Potheegadoo

As a clinical neuropsychologist, I appreciate working with clinical populations, as I constantly learn a lot from the patients, enriching my knowledge not only on the illness but also on clinical and research practice. I graduated from the University of Strasbourg (France), and obtained a Master's degree in clinical neuropsychology in 2005 from the University of Caen Basse-Normandie (France). I integrated the Psychiatry Department of the University Hospitals of Strasbourg as a neuropsychologist and pursued both clinical and research work on schizophrenia (INSERM unit). I investigated autobiographical memory impairment and self disorders in patients with schizophrenia, and obtained a Ph.D. in neuroscience (University of Strasbourg) in 2014. I joined the Blanke Lab (LNCO) as scientific collaborator in 2016.

Wulfram Gerstner

Wulfram Gerstner is Director of the Laboratory of Computational Neuroscience LCN at the EPFL. His research in computational neuroscience concentrates on models of spiking neurons and spike-timing dependent plasticity, on the problem of neuronal coding in single neurons and populations, as well as on the link between biologically plausible learning rules and behavioral manifestations of learning. He teaches courses for Physicists, Computer Scientists, Mathematicians, and Life Scientists at the EPFL. After studies of Physics in Tübingen and at the Ludwig-Maximilians-University Munich (Master 1989), Wulfram Gerstner spent a year as a visiting researcher in Berkeley. He received his PhD in theoretical physics from the Technical University Munich in 1993 with a thesis on associative memory and dynamics in networks of spiking neurons. After short postdoctoral stays at Brandeis University and the Technical University of Munich, he joined the EPFL in 1996 as assistant professor. Promoted to Associate Professor with tenure in February 2001, he is since August 2006 a full professor with double appointment in the School of Computer and Communication Sciences and the School of Life Sciences. Wulfram Gerstner has been invited speaker at numerous international conferences and workshops. He has served on the editorial board of the Journal of Neuroscience, Network: Computation in Neural Systems', Journal of Computational Neuroscience', and `Science'.

Aude Billard

Expertise RoboticsMachine LearningArtificial IntelligenceHuman-Robot InteractionMechatronicsDynamical Systems ControlComputational Neuroscience Aude Billard is full professor and head of the LASA laboratory at the School of Engineering at the Swiss Institute of Technology Lausanne (EPFL), and the Director of the Swiss Innovation Booster on Robotics. Dr. Billard acts as the President of the IEEE Robotics and Automation Society (RAS), after serving in several roles in the administrative and executive committe

Ayberk Ozkirli

Dr. Ayberk Ozkirli is a vision neuroscientist whose research investigates how spatiotemporal context influences visual perception.He completed his PhD in Neuroscience at the Laboratory of Psychophysics at EPFL in 2025, under the supervision of Prof. Michael Herzog and Prof. David Pascucci. He holds an M.Sc. in Bioengineering from EPFL (Switzerland) and a B.Sc. in Electrical and Electronics Engineering from Bilkent University (Turkey).His expertise spans neuroimaging, statistics, experimental design, neural

Michele Di Ponzio

Yunjoung Cho

Touradj Ebrahimi

Touradj EBRAHIMI received his M.Sc. and Ph.D., both in Electrical Engineering, from the Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland, in 1989 and 1992 respectively. In 1993, he was a research engineer at the Corporate Research Laboratories of Sony Corporation in Tokyo, where he conducted research on advanced video compression techniques for storage applications. In 1994, he served as a research consultant at AT&T Bell Laboratories working on very low bitrate video coding. He is currently Professor at EPFL heading its Multimedia Signal Processing Group. He is also the Convenor of JPEG standardization Committee. He was also adjunct Professor with the Center of Quantifiable Quality of Service at Norwegian University of Science and Technology (NTNU)from 2008 to 2012. Prof. Ebrahimi has been the recipient of various distinctions and awards, such as the IEEE and Swiss national ASE award, the SNF-PROFILE grant for advanced researchers, Four ISO-Certificates for key contributions to MPEG-4 and JPEG 2000, and the best paper award of IEEE Trans. on Consumer Electronics . He became a Fellow of the international society for optical engineering (SPIE) in 2003. Prof. Ebrahimi has initiated more than two dozen National, European and International cooperation projects with leading companies and research institutes around the world. He is a co-founder of Genista SA, a high-tech start-up company in the field of multimedia quality metrics. In 2002, he founded Emitall SA, start-up active in the area of media security and surveillance. In 2005, he founded EMITALL Surveillance SA, a start-up active in the field of privacy and protection. He is or has been associate Editor with various IEEE, SPIE, and EURASIP journals, such as IEEE Signal Processing Magazine, IEEE Trans. on Image Processing, IEEE Trans. on Multimedia, EURASIP Image Communication Journal, EURASIP Journal of Applied Signal Processing, SPIE Optical Engineering Magazine. Prof. Ebrahimi is a member of Scientific Advisory Board of various start-up and established companies in the general field of Information Technology. He has served as Scientific Expert and Evaluator for Research Funding Agencies such as those of European Commission, The Greek Ministry of Development, The Austrian National Foundation for Scientific Research, The Portuguese Science Foundation, as well as a number of Venture Capital Companies active in the field of Information Technologies and Communication Systems. His research interests include still, moving, and 3D image processing and coding, visual information security (rights protection, watermarking, authentication, data integrity, steganography), new media, and human computer interfaces (smart vision, brain computer interface). He is the author or the co-author of more than 200 research publications, and holds 14 patents. Prof. Ebrahimi is a member of IEEE, SPIE, ACM and IS&T. See the URL below for more details: http://mmspl.epfl.ch

Mahmut Sami Arpa

Francesca De Simone

I am a Post-doctoral fellow in the Signal Processing Laboratory (LTS4) EPFL, Lausanne, Switzerland, since November 2015. From January 2015 to October 2015 I worked as Senior Security Engineer, anti-piracy video streaming expert at Kudelski Group, Cheseaux-sur-Lausanne, Switzerland. Before that, from November 2012 to December 2014 I was Post-doctoral fellow in the Multimedia Signal Processing Lab at Institut Mines Telecom ParisTech, Paris, France, working with Dr. Frederic Dufaux. I received the Ph.D. degree in computer and information science from Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, in 2012 and M.S. degree in electrical engineering from University of Roma Tre, Rome, Italy, in 2006. My research interests concern omnidirectional imaging, multimedia quality assessment, image and video coding, video streaming, human attention modeling, highy dynamic range imaging, image and video representation and analysis, psychophysics, statistics. You can find an updated list of my publications at Google Scholar.

Pascal Frossard

Teaching & PhD PhD Students Yiming Qin, Alba Carballo Castro, Elisa Messori, Ke Wang, Sevda Ögüt, Tuna Alikasifoglu, William Cappelletti, Manuel Madeira, Mahdi Amiri, Ortal Yona Senouf, Vasiliki Rizou, Cem Bilaloglu, Abdellah Rahmani, Amel Abdelraheem, Jérémy Jean Philippe Baffou, Adam Hazimeh, Vincent Jung, Yike Zhao Past EPFL PhD Students Dan Jurca, Jean-Paul Wagner, Ivana Radulovic, Ivana Tosic, Effrosyni Kokiopoulou, Zafer Arican, Vijayaraghavan Thirumalai, Tamara Tosic, Eirina Bourtsoulatze, Elif Vur

Related units (4)

Foundation Bertarelli Chair in Cognitive Neuroprosthetics

Laboratory of Integrated Performance in Design

Medical Image Processing Laboratory

Related concepts (6)

Hallucinogen

Hallucinogens are a large and diverse class of psychoactive drugs that can produce altered states of consciousness characterized by major alterations in thought, mood, and perception as well as other changes. Most hallucinogens can be categorized as either being psychedelics, dissociatives, or deliriants. The word hallucinogen is derived from the word hallucination. The term hallucinate dates back to around 1595–1605, and is derived from the Latin hallūcinātus, the past participle of (h)allūcināri, meaning "to wander in the mind.

Visual snow syndrome

Visual snow syndrome (VSS) is an uncommon neurological condition in which the primary symptom is that affected individuals see persistent flickering white, black, transparent, or coloured dots across the whole visual field. Other common symptoms are palinopsia, enhanced entoptic phenomena, photophobia, and tension headaches. The condition is typically always present and has no known cure, as viable treatments are still under research. Astigmatism, although not presumed connected to these visual disturbances, is a common comorbidity.

Optical illusion

In visual perception, an optical illusion (also called a visual illusion) is an illusion caused by the visual system and characterized by a visual percept that arguably appears to differ from reality. Illusions come in a wide variety; their categorization is difficult because the underlying cause is often not clear but a classification proposed by Richard Gregory is useful as an orientation. According to that, there are three main classes: physical, physiological, and cognitive illusions, and in each class there are four kinds: Ambiguities, distortions, paradoxes, and fictions.