science

Hallucinogen persisting perception disorder

Hallucinogen persisting perception disorder is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Hallucinogen persisting perception disorder rather than just read about it. In short: Hallucinogen persisting perception disorder (HPPD) is a non-psychotic disorder in which a person experiences lasting or persistent visual hallucinations or perceptual distortions after using drugs such as psychedelics, dissociatives, deliriants, entactogens, and cannabinoids. Symptoms may include visual snow, trails and after images (palinopsia), light fractals on flat surfaces, intensified colors, altered motion pe…

Key takeaways

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Reference excerpt

Hallucinogen persisting perception disorder (HPPD) is a non-psychotic disorder in which a person experiences lasting or persistent visual hallucinations or perceptual distortions after using drugs such as psychedelics, dissociatives, deliriants, entactogens, and cannabinoids. Symptoms may include visual snow, trails and after images (palinopsia), light fractals on flat surfaces, intensified colors, altered motion perception, pareidolia, micropsia, and macropsia. Floaters and visual snow may occur in other conditions. For the diagnosis, other psychological, psychiatric, and neurological conditions must be ruled out, and they must cause distress in everyday life. In the DSM-5 it is diagnostic code 292.89 (F16.983). In the ICD-10, the diagnosis code F16.7 corresponds most closely. It is rarely recognized by hallucinogen users and psychiatrists, and is differentiated from hallucinogen-induced psychotic disorder in that it does not involve paranoia, insomnia, changes in thinking, or delusions, and relates to lasting visual changes only. It is divided into two types, 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 associated mental disorders. Some people report symptoms after their first use of drugs (most notably LSD). There is little information on effective treatments. The underlying mechanisms are not well understood. One hypothesis suggests that anxiety may amplify existing visual disturbances and potentially trigger these visual phenomena. Many report that their visual distortions become more pronounced or even emerge during periods of heightened anxiety or stress.

Symptoms Typical symptoms of the disorder include halos or auras surrounding objects, trails following objects in motion, difficulty distinguishing between colors, apparent shifts in the hue of a given item, the illusion of movement in a static setting, visual snow, distortions in the dimensions of a perceived object, intensified hypnagogic and hypnopompic hallucinations, monocular double vision, seeing an excessive amount of eye floaters, the morphing of multiple objects into one texture, and blue field entoptic phenomenon. 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. Visual aberrations can occur periodically in healthy individuals – e.g., afterimages after staring at a light, noticing floaters inside the eye, blue field entoptic phenomenon, or seeing specks of light in a darkened room. However, in people with HPPD, symptoms seem typically to be worse, but complications come from the additional roles played by anxiety and fixation. Indeed, anxiety has been implicated in visual perceptual effects similar to HPPD, and authors have recognized the crucial role of attending to underlying anxiety and panic in recovering from the disorder. There is some uncertainty about to what degree visual snow constitutes a true HPPD symptom. There are individuals who have never used a drug which could have caused the onset, but yet experience the same grainy vision reported by those with HPPD, like people with the closely-linked neurological disorder known as visual snow syndrome. There are a few potential reasons for this, the most obvious of which is the theory that the drug usage may exaggerate the intensity of visual snow. At the same time, beyond the characteristic visual snow symptom, there is considerable overlap between the conditions, including after-images, palinopsia, tinnitus, dissociation, and free-floating anxiety, leading some to suggest that HPPD shares a strong relationship with visual snow syndrome. Visual snow syndrome is defined as lacking any known cause and is specifically distinguished from HPPD in its nosology, yet further research may clarify the relationship. HPPD usually has a visual manifestation, but some hallucinogenic and psychiatric drugs affect the auditory sense and can produce tinnitus-like symptoms as a side effect, and there are many anecdotal reports of people getting tinnitus with their HPPD. A significant number of those reporting HPPD also describe comorbid depersonalization-derealization and anxiety disorders. Anxiety, PTSD and panic can promote depersonalization-derealization and visual disturbances, and vice versa, so these features may run in multidirectional relationships. Abraham suggested that all three can arise from a broader mechanism of disinhibition in sensory perception, affect and sense-of-self occasioned by psychedelic experience. It is not uncommon for depersonalization-derealization to be the most distressing symptom of the condition. According to a 2016 review, there are two theorized subtypes of the condition. Type 1 HPPD is where people experience random, brief flashbacks. Type 2 HPPD entails experiencing persistent changes to vision, which may vary in intensity. This model has faced scrutiny, however, due to "flashbacks" often being considered a separate condition and not always a perceptual one.

Causes

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Illustrations

Hallucinogen persisting perception disorder illustration

Worked examples

Example 1 — a first encounter with Hallucinogen persisting perception disorder

Start with the simplest possible case. Write down what Hallucinogen persisting perception disorder claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Hallucinogen persisting perception disorder before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Hallucinogen persisting perception disorder ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Hallucinogen persisting perception disorder

In research: Hallucinogen persisting perception disorder appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Hallucinogen persisting perception disorder in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Hallucinogen persisting perception disorder is common in secondary-school and first-year university syllabi. It links to neighbouring topics Drug culture, Effects of psychoactive drugs, Hallucinations, so understanding it makes those chapters shorter.
In everyday life: Look for Hallucinogen persisting perception disorder outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Hallucinogen persisting perception disorder in 20 minutes

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Close the page and write down what Hallucinogen persisting perception disorder means in your own words.
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Frequently asked questions

What is Hallucinogen persisting perception disorder in simple terms?

Why does Hallucinogen persisting perception disorder matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Hallucinogen persisting perception disorder?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Hallucinogen persisting perception disorder.