Jump to content

Recommended Posts


"Characterization, Frequency and Severity of Visual Phenomenology in Adults with Hallucinogen Persisting Perception Disorder"

Name and address of the principal investigator
David S. Kozin, 

Site where the study will be performed: Online. The study will be carried out at the office of the principal investigator with 256-bit SSL encrypted server access.


Hallucinogen Persisting Perception Disorder (HPPD) is a persisting, post-substance use disorder characterized by the diagnostic criterion of “the re-experiencing, 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 colors, intensified colors, trails of images of moving objects, positive afterimages, halos around objects, macropsia, and micropsia.” (DSM-5 (update definition)). Abraham (1993) completed the most complete characterization of symptoms Additionally, individuals reporting HPPD and anecdotal evidence from online support message boards suggest that a prominent portion of this population presents symptoms of depersonalization disorder and derealization without clinical memory or identity alterations typically present in other dissociative disorders (Simeon & Kozin et al, unpublished data). The course of HPPD with the most significant distress is typically chronic and continuous (Lerner  et al. 2002 & online descriptions), however the DSM-5 (update definition) does not differentiate between the chronic and transient forms of perceptual disturbances as independent diagnostic entities (APA 2004).

HPPD often lasts for years and often individuals with significant symptom severity with have the disorder for over 30 years and likely will not end until the end of their lives. The triggering of the visual symptoms does not always occur immediately after the precipitant drug, but has been been reported to be associated either with trauma (self-reports) or a non-hallucinogenic drug is the precipitant, or increases symptoms (Alcántra, (1998), Favazza & Domino (1969), Lauterbach et al (2000) , Lerner et al (2002), Markel et al (1994), Morehead & Morehead (1997), Scott (1971), & Solhkhah (2000), unpublished online reports). 

Dr. Roger Davis and David Kozin created a complete set of visual simulators for the symptoms described in Abraham’s 1983 symptom list. Davis and Kozin used images from individuals from an online HPPD community and completed a one week session where each visual simulator we presented to a live audience of individuals from the HPPD online community to constantly discuss with Davis and Kozin regarding the accuracy of each image. Ultimately, we need a catalogue of HPPD visual disturbances and these simulators are able to be included as tools within the survey. This could help develop an online catalogue where each "plate" in the represents a reference point through which patients can explain their vision to mental health professionals and other doctors. Unfortunately, at this point we we do not have a systematic and objective result from participants on their responses to these images.  Eventually, the entire catalog of simulators could be distributed online for clinical consumption for doctors to help them understand HPPD perceptual disturbances, acquainting them with the disorder, and perhaps averting tragedies where, for example, HPPD patients are misdiagnosed with schizophrenia and given antipsychotic drugs that can worsen the disorder.

It is the goal of this survey to descriptively and systematically study in greater depth the frequency, duration, and severity of the visual symptoms of HPPD, the relationship between illicit and non-illicit drug use and HPPD-like symptoms, investigate other additional possible psychopathologies with valid instruments and/or self-report, and to investigate the differences between chronic and transient subtypes. 

In light of the DSM-V’s goal of a dimensional approach to diagnosis, and also to not make the mistake of the DSM-III and IV to sacrifice validity over stability (personal communications with APA Task Force members during the ISSTD conference), a study that helps identify and improve diagnostic precision for these persisting drug-induced experiences, either transient or chronic, will help with choosing treatments and improving and clarifying research with improved definitions to match the variability in these disorders. This will improve the validity of the diagnosis, and lead to proper treatments associated with each subtype. 

Mood, anxiety and personality disorders are often comorbid with HPPD, but none have been examined to predict symptom severity. The most common proximal precipitants of the disorder are hallucinogens (specifically HPPD), however non-hallucinogens have been reported to cause similar symptoms. These will be investigated by allowing non-hallucinogen users to participate if they match the visual symptom criteria and including a standard scale to measure mood and anxiety. Axis II disorders will unlikely be able to be examined within the time-frame anticipated for this study.

Reports from online forums for people with HPPD (such as the forum at http://www.hppdonline.com) and clinical experience suggests that: 1) The current DSM-5 (update definition) diagnosis for HPPD encompassed two disorders that have distinctly different etiologies and treatment responses, the clinical community lacks awareness of the complexity of this disorder (indicated by textbooks often referring only to the transient “flashback” type [examples are available]), and researchers reporting HPPD case studies often fail to mention chronic HPPD, and although treatments listed in the literature may be successful for flashback type, they are not proven to be successful in the chronic type – this could lead to unnecessary medication treatments for individuals with HPPD and increased cost of their health care. Potential subjects for this study, unsolicited and written in a public forum, often report on the message board or personal communication that the DSM-5 (update definition)’s inclusiveness of the phrase “flashbacks” in the name of the diagnosis as well as the often mis-use of the word in the literature has resulted in the clinician treating a chronic HPPD patient as one with temporary flashbacks resulting in the patient leaving therapy and not returning and feeling discouraged.

Research Objectives and Hypothesis

The purpose of this study is to investigate if the current definition of Hallucinogen Persisting Perception Disorder, excluding the criterion of the DSM-5 (update definition) requiring hallucinogen use, to produce multiple groups and to characterize the symptoms, comorbid disorders, and serve as the largest systematic study of HPPD participants to date. The study will gather accounts of people with vision problems not caused from hallucinogens and to investigate visual symptoms from drugs that have been reported in the literature. The hypothesis is that the current diagnosis truly encompasses two distinct sub types, and dimensional scales measuring the frequency, severity, and treatment responses will create two clusters within the current diagnosis.

Study Design and Research Methods

This survey will be posted on the internet, and we expect to recruit 200 participants over a 6-month period. Only individuals over the age of 18 will be eligible to take part. To expedite IRB review, one method would be to make the survey anonymous and protect the privacy of the participants by not inquiring about any identifying demographics, such as name, date of birth, address, or phone numbers, nor submission of e-mail addresses. However, including an initial phone interview, which could be done without recording personal data, could be set-up with the current survey software to have an initial interview over the phone and providing a unique “token” to an individual to ensure non-repeaters and help increase the potential that the participants do fit within our qualifications of having visual symptoms to those defined in HPPD. In this latter format, a participant will be able to take part in the study by contacting the laboratory by phone or e-mail, and afterwards the participant receive a token which will be activated after one day. When the 24 hours from the receipt of the token have elapsed, participants will be able to enter the survey page, enter their token information, and begin the survey. Upon completion of the survey, each token will no longer be useable and the participants will be debriefed. 

Subjects will be recruited through HPPD related websites , other Internet forums related to drug-use, potentially advertised, and will require the participant to complete an online consent form.

Subjects will submit an online consent statement and questionnaire with questions on

1. Demographic information

2. A list of questions structured to diagnose HPPD based on DSM-5 (update definition) criteria

3. Drug History, past and current.

4. Using dimensional scales to rate frequency, duration, and severity of visual symptoms. questions will inquire about the disorder in-depth based on the information collected both in the literature and also using language collected from the community from the on-line support message board (Symptoms Descriptions and Stories from public forum are listed below).

 6. Effects of treatments with self-reported measures of their effectiveness using the standard 7-point ical Global Impression – Improvement Scale (CGI-I)

8. The Sheehan Disability Scale will be administered. If the participant answers questions consistent with the DES, then they will be branched to take the Cambridge Depersonalization Scale.

 7. Allow for a free-text description of symptoms and story for clinical narratives.  

8. Include vision simulators and images for judging accuracy of these items.

Regarding the survey design and my discussions with Roger Davis, in terms of the psychometrics, we would consider using the  Rasch
model to derive the scales with the goal of leading to uni-dimensional scales with a good distribution of item difficulties, this will be
necessary to quantify the disorder well at every point along its severity. We don't want to end up with scales that measure the  disorder only at the more severe levels. Once we reach this point, we'll have a set of scales that could potentially be used in a next step for validation to be used by the individual clinician to assess  an HPPD patient and be used by a researcher who wants to further investigate the syndrome (creating a uniform HPPD diagnosis versus the current variants of language in the literature where clinicians are using the same words to imply different syndromes). I believe this would be a reasonable first step, and also would produce a publication that allows for an updated review of HPPD. I realize that the DSM-III and  IV sacrificed validity for reliability. In my opinion, moving back towards empirical research, it could be  useful  in discussing the possibility for suggesting (aligned with Lerner's publication and what we see online and in clinical settings) the consideration of lobbying for two subtypes of HPPD: transient flashbacks and continuous/chronic. Although I realize the knowledgeable clinician should consider this diagnosis correctly, we  have seen in the literature the amount of flashback case studies, undifferentiated from chronic HPPD, eventually find homes in the pages of medical web sites and textbooks that characterize HPPD solely based on HPPD of the flashback variety. I have read many stories from  HPPD'rs where this has caused considerable difficulty when trying to explain  to the clinician the suffering caused from full-time perceptual disturbances and needing treatment to deal with their concern for its potential permanence; this often goes invalidated by the clinician because of the word "Flashbacks" associated with HPPD in the DSM-5.

The database of responses will be stored indefinitely in a locked filing cabinet. Data extracted will be stored in an SPSS data file, MySQL db, and Excel spreadsheet file saved on computers in the locked office of the principal investigator (same location). 

Women and minorities will be included. Based on registration, members of online support message boards for HPPD are more often males, so we anticipate considerably greater participation among males (HPPDonline.com statistics). Subjects will not be audio- or videotaped. Subjects will not receive any payment for participation. 

There are no potential risks to the subjects from participation in this study except for potential loss of confidentiality regarding their medical condition, which we minimize by keeping medical records in a locked filing cabinet in a locked office in a locked building. There are no direct benefits to the individual subject, nor is compensation provided for participation; however, the subject and society may benefit indirectly if this study leads to greater understanding of HPPD.

Descriptive statistics, two-sample comparisons between transient and chronic cases, and an exploratory factor analysis will be used to evaluate data collated from the survey. Dr. Roger Davis has agreed to help with question and study design and pilot testing the study with students in his graduate-level class on “Methodology  of Psychometric Instrument Design”.

Anticipated Results and Potential Pitfalls

We expect the results will yield two psychometrically valid, clinically meaningful, and possibly conceptually discrete underlying dimensions of Hallucinogen Persisting Perception Disorder. Therefore, the derived frequency and symptom sets are well suited for a prospective field trial study using an adapted structured interview in an effort to derive clinically useful diagnostic criteria for HPPD for the DSM-V. We may also find evidence of positive and negative treatment self-reports dependent on subtype (for instance, greater efficacy of clonazepam for symptom reduction in chronic sub-type over periodic.) Pitfalls include that the survey precludes face-to-face diagnostics for Axis I disorders and is retrospective in nature,; however, methodological shortcomings are well recognized and characteristic of Internet-based surveys with self-referral. However, selection bias is minimized by including and advertising on targeted web sites to include individuals reporting to fit in the diagnosis and including questions designed to target individuals likely to be exaggerating symptoms, and possible inclusion of other validated scales. Additionally, using the initial phone inclusion method could help reduce common problems with online surveys. A prior online survey yielded strikingly similar results on standardized scales compared to those including diagnositics (Simeon & Kozin et al 2008 & Simeon & Kozin et al 2009)

Discussion of Next Steps

If  acute and chronic types do form two distinct quantitatively valid subtypes, then two-sample comparisons between both groups and also between the hallucinogen-induced and non-hallucinogen induced groups will help will provide evidence for the difference between these groups and lead to an improved diagnosis that will follow in the spirit of the new DSM-V of designing diagnoses with the goal of ultimately benefiting the patient and lead to improved clarity of diagnosis for improved research. The study would score severity and frequency and seek a possible dimensional model for symptom descriptions, uncovering an effective HPPD symptom lexicon that should be shared with neurologists, ophthalmologists, and mental health professionals. Defining the perceptual disturbances with unified symptom descriptions within the disorder will improve the precision of the diagnosis and lead to improved treatment methods.

Link to comment

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.