Table 3.

Observational studies and case reports comparing schizophrenic patients with HPPD (SCZ+HPPD) and schizophrenic patients without HPPD (SCZ) (* p > 0.05, ** p < 0.05).

Authors	Study	Number of Patients	Substances	Symptoms Description	Onset Perceptual Disorders	Recurrence of Perceptual Disorders	Treatment
Lev-Ran, 2015 [57]	Observational, cross-sectional, control study	80 hospitalized SCZ patient with past use of LSD 43 SCZ (DSM-IV-TR) 37 SCZ+HPPD (DSM-IV-TR) Onset of illness: 22.9 SCZ, 23.4 SCZ+HPPD *	Cannabis: 100% SCZ, 92% SCZ+HPPD * MDMA: 60% SCZ, 46% SCZ+HPPD * Opioids: 26% SCZ, 30% SCZ+HPPD 30% * Cocaine: 16% SCZ, 14% SCZ+HPPD * LSD initiation use: SCZ 17.9y, SCZ+HPPD 19.3y *	Adversive LSD experience (bad trip): 28% SCZ, 89% SCZ+HPPD ** PANSS: Positive symptoms: SCZ = SCZ+HPPD ** Negative symptoms: SCZ > SCZ+HPPD ** General psychopathology: SCZ > SCZ+HPPD ** Total score: SCZ > SCZ+HPPD **		Treatment ineffective in SCZ+HPPD	Antipsychotic medication
Lev-Ran, 2014 [58]	Observational	26 patients 14 SCZ (DSM-IV-TR)12 SCZ+HPPD (DSM-IV-TR) Demographic characteristic did not differ between the two groups	Past use of :LSD (100%) cannabis (100%) MDMA (7%) No differences between the two groups in age at onset of drug use and in number of incidences of hallucinogen use	67% SCZ+HPPD could distinguish HPPD symptoms from hallucination related to a psychotic state	9 SCZ+HPPD patients recognized precursory cues for perceptual distortion (7 substance-induced, 5 situational, and 2 mental cues)	12 patients experienced perceptual distortion (SCZ+HPPD)	Antipsychotic treatment. No significant differences in response to APS and adverse effects between the two groups
Lauterbach, 2000 [60]	Case report	1 psychotic patient	No reported substance abuse and hallucinogen exposure Risperidone Clonazepam Trazodone	HPPD-like symptoms: palinopsia, illusions, and visual disturbances	After risperidone treatment	Weekly recurrence. Remission in 48 h each time