HPPD – A Very Brief Summary based on Halpern, Lerner & Passie (2016)
Hallucinogen Persisting Perceptual Disorder (HPPD) is included in the DSM-5 as a clinical diagnosis and psychedelics are only one of the few known probable causes of HPPD. Symptoms have been found to occur in otherwise healthy normal populations. There are two recognized classifications of HPPD: Type 1, which are brief “flashbacks,” and Type 2 claimed to be chronic, waxing, and waning over months to years. It therefore might be valuable to reformulate how HPPD is defined according to symptoms, commonly including: difficulty with light accommodation, difficulty concentrating, halos/auras, floaters, difficulty communicating, afterimages, trails, tinnitus, visual snow, head pressure, ghosted afterimage, and swaying/moving stationary objects.
HPPD is more common in recreational users than in clinical populations, where it is virtually non-existent (Johnson 2008). Some factors were found predicting occurrence of HPPD, including pre-existing tinnitus, “floaters,” and trouble concentrating, but most importantly, anxiety and panic reactions during the experience. This has led to speculation on hallucinogen-induced PTSD symptomatology as a useful model for HPPD. An alternative view proposes HPPD may represent a worsening of pre-existing visual sensitivity.
Cannabis, MDMA, stimulants, and antipsychotics have been reported to potentially worsen symptoms of Type 2 HPPD, while psychotherapy, sedative-hypnotics, opioids (and opioid antagonists), clonidine, and sunglasses have been reported to potentially ameliorate symptoms. Not mentioned in this review is the potential for Lion’s Mane often anecdotally credited for treating symptoms of HPPD. Reducing the frequency and duration of the panic reactions during the experience reduce the likelihood of developing symptoms of HPPD. Regular mindfulness meditation practice appears to negatively predict anxious and panic reactions during the psychedelic state, as does the presence of a trusted, calming, non-judgemental guide.