Synthetic Cannabis Substances (SPS) Use and Hallucinogen Persisting Perception Disorder (HPPD): Two Case Reports.

Hallucinogen Persistent Perceptual Disorder (HPPD) is a clinical syndrome characterized by the recurrence of distressing perceptual disturbances which previously emerged during primary hallucinogen intoxication, in the absence of recent use. Here we present two patients who developed HPPD following use of Synthetic Cannabis Substances (SCS), with no prior history of natural-occurring or synthetic hallucinogen use. Both cases had a prior history of cannabis dependence and current tobacco dependence. In both cases patients reported the presence of visual disturbances when smoking SCS and staring at stationary and moving objects. Both patients discontinued SCS use abruptly after suffering from a panic attack under the influence of SCS. Despite cessation of SCS, both patients continued to suffer from HPPD which was accompanied by significant anxiety. Following clonazepam treatment, both subjects reported significant improvement in symptoms and remained with a residual focal visual disturbance which was not accompanied by significant anxiety. To the best of our knowledge these are the first reports of HPPD following SCS use. In light of the increasing use of SCS, clinical psychiatrists should be aware of these perceptual side effects.