Abstract
Objective: To describe a brief psychotic episode temporally associated with dose escalation of osmotic-release oral system methylphenidate (OROS MPH) in an adolescent with attention-deficit hyperactivity disorder (ADHD).

Methods: We report the clinical course of a 15-year-old female with ADHD who developed acute psychotic symptoms after OROS MPH was increased from 36 to 54 mg/day. Clinical findings, laboratory tests, cranial magnetic resonance imaging, family history, treatment course, and causality using the Naranjo Adverse Drug Reaction Probability Scale were evaluated.

Results: Psychotic symptoms, persecutory delusions, a thought-reading-like experience, brief grandiose delusions, insomnia, and disorganized behavior, emerged approximately 8–10 hours after the first 54 mg/day dose (~1.17 mg/kg/ day). There was no overdose and no sign of stimulant intoxication. Complete blood count, metabolic panel, and cranial magnetic resonance imaging were normal. Family history was notable for undocumented persecutory delusional beliefs in the paternal grandfather. MPH was discontinued and the symptoms resolved completely within 48 hours without antipsychotic treatment. The Naranjo score was 7, indicating a probable adverse drug reaction.

Conclusion: Psychotic symptoms may emerge abruptly after MPH dose escalation even within the therapeutic dose range. Careful dose titration, attention to possible vulnerability factors, and prompt discontinuation when psychotic symptoms occur are important.

Key words: ADHD, Case report, Family history, Methylphenidate, Psychosis