Talk:Hallucinogen persisting perception disorder

From PsychonautWiki
Jump to navigation Jump to search

Hallucinogen persisting perception disorder (abbreviated as HPPD) is a psychiatric disorder characterized by the persisting presence of sensory disturbances, most commonly visual, that resemble those that are produced by the use of hallucinogenic substances. HPPD exists in two forms; type 1, which details brief “flashbacks,” and type 2, which is claimed to be chronic, waxing and waning over months to years.[1] Previous use of hallucinogens is necessary, but not sufficient, for diagnosis of HPPD, and the symptoms cannot be due to another medical condition. Clinically meaningful impairment in everyday functioning and/or suffering are required for its diagnosis.

Requirements for formal diagnosis

The DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) is the 2013 update to the American Psychiatric Association's (APA) classification and diagnostic tool. In the United States, the DSM serves as a universal authority for psychiatric diagnoses. The requirements for formally being diagnosed with HPPD in the DSM include:[2]

(A) "The reexperiencing, following cessation of use of a hallucinogen, of one or more of the perceptual symptoms that were experienced while intoxicated with the hallucinogen (e.g., geometric hallucinations, false perceptions of movement in the peripheral visual fields, flashes of color, intensified colors, trails of images of moving objects, positive afterimages, halos around objects, macropsia, and micropsia)"

(B) "The symptoms in Criterion A cause clinically significant distress or impairment in social, occupational, or other important areas of functioning"

(C) "The symptoms are not due to a general medical condition (e.g., anatomical lesions and infections of the brain, and visual epilepsies) and are not better accounted for by another mental disorder (e.g., delirium, dementia, and schizophrenia) or hypnopompic hallucinations"

While many hallucinogen users report experiencing persisting perceptual effects (minor visual distortions following the use of substances like LSD, 2C-B and psilocybin mushrooms), this does not necessarily mean they have HPPD. They may merely be experiencing persisting hallucinogenic effects (such as mild visual drifting or intensified colors) which may not have any significant impact on their lives otherwise. It is only when these persisting hallucinations become disruptive enough to cause "clinically significant distress" or "impairment in social, occupational, or other important areas of functioning" that one's experience of persisting hallucinations qualify as a formal diagnosis for HPPD.


HPPD noise simulation, often referred to as visual snow

Typical symptoms of HPPD include,

  • Halos or auras surrounding objects
  • Trails following objects in motion (tracers)
  • Difficulty distinguishing between colors
  • Apparent shifts in the hue (color) of a given item
  • The illusion of movement in a static setting
  • Air assuming a grainy or textured quality (visual snow or static, not to be confused with normal "blue field entoptic phenomenon"), distortions in the dimensions of a perceived object, and a heightened awareness of floaters.

The visual alterations experienced by those with HPPD are not homogeneous, and there appear to be individual differences in both the number and intensity of symptoms.[citation needed] Visual aberrations can occur periodically in healthy individuals – e.g. after images after staring at a light, noticing floaters inside the eye, or seeing specks of light in a darkened room. However, in people with HPPD, symptoms are typically persistent enough that the individual cannot ignore them. [citation needed]

There is some uncertainty about to what degree visual snow constitutes a real HPPD symptom. Many individuals have never used a substance which could have caused the onset, but yet experience the same grainy vision reported by HPPD sufferers. There are a few potential reasons for this, the most obvious of which being the theory that the drug usage may exaggerate the intensity of visual snow. Another theory is that instead, there may be no change in the severity or magnitude of the visual snow, but perhaps the drug usage opens visual pathways that result in the individual becoming more aware of any visual disturbances that may have simply not been noticed before the incidence of substance use.

As for root cause of visual snow, some theories suggest that it is the result of thermal noise in the visual cortex or the "Optic Pathway" encompassing photoreceptor cells on the retina, the optic nerve, and the optic chiasm, [3] as eye tests for individuals who experience visual snow often reveal that physically, the eye is perfectly normal, and in many cases, the individual still maintains 20/20 vision.

HPPD usually has a visual manifestation. Drugs affecting the auditory sense, like diisopropyltryptamine (DiPT), may produce auditory disturbances, though there are few known cases. Some hallucinogenic substances can produce temporary tinnitus-like symptoms as a side effect.[4][5]

It also should be noted that the visuals do not constitute true hallucinations in the clinical sense of the word. People with HPPD recognize the visuals to be illusory or pseudohallucinations, and thus maintain the ability to distinguish what is real (in contrast to some mental illnesses such as schizophrenia).[6]


The first formal description of “a repetition of the acute phase of the experience days or even weeks after the initial doses” emerged from a study of LSD-assisted psychotherapy (Sandison and Whitelaw 1957). Around 1970, the term “flashback” began to appear in the literature; as in Heaton and Victor (1976): “A flashback is the transient recurrence of psychedelic drug symptoms after the pharmacologic effects of such drugs have worn off and a period of relative normalcy has occurred.”


  • Halpern, J. H., & Pope, H. G. (2003). Hallucinogen persisting perception disorder: what do we know after 50 years?. Drug and Alcohol Dependence, 69(2), 109-119.
  • Halpern, J. H., Lerner, A. G., & Passie, T. (2016). A review of hallucinogen persisting perception disorder (HPPD) and an exploratory study of subjects claiming symptoms of HPPD. Curr Top Behav Neurosci. 2016 Nov 8. [Epub ahead of print]

External links


  1. Halpern, J. H., Lerner, A. G., & Passie, T. (2016). A review of hallucinogen persisting perception disorder (HPPD) and an exploratory study of subjects claiming symptoms of HPPD. Curr Top Behav Neurosci. 2016 Nov 8. [Epub ahead of print]
  2. American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders: DSM-5. Washington, D.C: American Psychiatric Association.
  3. Baylor, D. A., Matthews, G., & Yau, K. W. (1980). Two components of dark electrical noise in toad retinal rod outer segments. The Journal of Physiology, 309, 591.
  4. Shulgin, A., & Shulgin, A. (1991).Erowid Online Books: "TIHKAL" - #36 - 5-MeO-DET. Retrieved April 14, 2017.
  5. Erowid. (2003). Erowid Experience Vaults: DiPT - More Tripping & Revelations - 26540. Retrieved from
  6. Moskvitin, J. (1974). Essay on the origin of thought. Athens: Ohio University Press.