P.3.024 - Visual hallucinations and lifetime use of hallucinogen perception persisting disorder associated recreational drugs: results from a large online survey

Abstract

Introduction Hallucinogen perception persisting disorder (HPPD) can be defined as the re-experience of altered visual perceptions after use of psychedelic drugs [1,2]. Despite estimated high percentages of recreational use of psychedelic drugs, research data on HPPD are scarcely available [1,2]. Considering the recent emergence of studies on psychedelic drugs as a treatment option for various psychiatric disorders, proper assessment of potentially harmful side effects, such as HPPD, is necessary [3]. This study aims to investigate the association between lifetime use of HPPD-associated drugs and the presence and burden of visual hallucinations in a large general population sample. Methods We used data from a large online survey on hallucinations in the general Dutch population, https://zieikspoken.nl, collected between September 26th, 2016 and May 23rd, 2017. All participants (n=10.289) were aged 14 or over. We assessed lifetime use of 11 commonly used recreational drugs in the Netherlands, out of which LSD, psilocybin, 2-CB and MDMA were considered HPPD-associated based on previous reports [1-4]. Visual hallucinations were assessed using the Questionnaire for Psychotic Experiences (QPE). Presence of visual hallucinations was categorized as follows: never experienced, ever experienced, experienced in past month, experienced in past week. Associations between lifetime use of HPPD-associated drugs and presence and phenomenology of visual hallucinations were calculated using Pearson’s chi-square tests in SPSS. Results A total of 2.175 subjects (21.1% of all participants) indicated having used HPPD-associated drugs at least once in their lifetime. In subjects who had never experienced visual hallucinations, the percentage of lifetime HPPD-associated drug use (18.8%) was significantly lower than in the groups who had experienced visual hallucinations in their lifetime but not recently (23.0%), in the past month (25.2%) or the past week (24.9%). Nevertheless, lifetime use of HPPD-associated drugs did not differ between the groups of subjects with visual hallucinations (ever/past month/past week). Within the group of subjects with visual hallucinations in the past week or month, lifetime HPPD-associated drug users did not differ from non-users in terms of experiencing a significant burden from their visual hallucinations (25.2% vs. 24.1%, respectively; OR 0.9 (95%-CI 0.7-1.2)) or having visual hallucinations with a significant impact on their daily functioning (25.1% vs 23.0%; OR 0.9 (95%CI 0.6 -1.4)). Discussion Our results indicate that lifetime exposure to HPPD-associated drugs is associated with a slight but significant increase in presence of visual hallucinations. However, the experienced burden of current visual hallucinations and their impact on daily functioning does not differ between the exposed and unexposed group. Our study is limited to cross-sectional data not specifically focused on HPPD-like perceptual disturbances. Despite this, our results are in line with previous studies, in which the presence of chronic, burdensome perceptual disturbances after psychedelic drug use is considered a rare phenomenon, whose occurrence relies on an overall vulnerability based on the combined presence of several risk factors, rather than on the lifetime exposure to HPPD-associated drugs alone [1-4]. With regard to future studies on psychedelic drugs, we still recommend to be careful by thoroughly measuring HPPD-like symptoms over time, and studying potentially contributive factors.