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Abstract: Two schizophrenic patients, who had a prior history of LSD abuse and who had previously developed EPS with classic antipsychotics, were successfully treated with risperidone. They both reported short episodes of transient visual disturbances, which appeared immediately after starting treatment with risperidone. This imagery resembled visual disturbances previously experienced as "flashbacks" related to prior LSD consumption. Risperidone administration was continued and the visual disturbances gradually wore off. During a six-month follow-up period, there was no recurrence of visual disturbances. This phenomenon may be interpreted as a benign, short-term and self-limiting side effect which does not contraindicate the use of risperidone or interfere with treatment. Conclusions based on two case reports should be taken with appropriate caution.
Introduction
The co-morbidity of schizophrenia and substance related disorders is well documented (1). The recognition and understanding of this coexistence is of importance in the management of these primarily schizophrenic patients (2).
On occasion, previous or current users of hallucinogens may experience a recurrence of some of the symptoms which previously appeared during intoxication, in the absence of recent intake (3,4,5). This disorder, hallucination persisting perception disorder (HPPD) according to DSM-IV, is a condition in which the re-experiencing of one or more perceptual symptoms causes significant distress or impairment in social, occupational or other important areas of functioning (6).
There are reports on the worsening of the HPPD symptomatology experienced by nonschizophrenic patients after the administration of the novel agent risperidone (7, 8). These observations raise questions regarding the effects of risperidone when used in the treatment of schizophrenic patients who complain of concurrent LSD-related recurrent visual phenomena.
Case 1
A. was a 25-year-old single male with paranoid schizophrenia (6). He began using cannabis at the age of 18, and consumed LSD infrequently at the age 22. He had pleasant and funny hallucinogenic experiences as a consequence of these "good trips." He occasionally experienced spontaneous visual phenomena, mainly trails of light or shadows following moving objects, intensified colors, or illusions of movement when looking down. They lasted fractions of a second, and were partly controllable. He described these recurrences as benign and pleasant in nature. He complained, however, that he was also experiencing "very long trips" and "very long flashbacks." Something was apparently going wrong. He...