Dual cases of type 1 narcolepsy with schizophrenia and other psychotic disorders.

OBJECTIVE: Cases of narcolepsy in association with psychotic features have been reported but never fully characterized. These patients present diagnostic and treatment challenges and may shed new light on immune associations in schizophrenia.
METHOD: Our case series was gathered at two narcolepsy specialty centers over a 9-year period. A questionnaire was created to improve diagnosis of schizophrenia or another psychotic disorder in patients with narcolepsy. Pathophysiological investigations included full HLA Class I and II typing, testing for known systemic and intracellular/synaptic neuronal antibodies, recently described neuronal surface antibodies, and immunocytochemistry on brain sections to detect new antigens.
RESULTS: Ten cases were identified, one with schizoaffective disorder, one with delusional disorder, two with schizophreniform disorder, and 6 with schizophrenia. In all cases, narcolepsy manifested first in childhood or adolescence, followed by psychotic symptoms after a variable interval. These patients had auditory hallucinations, which was the most differentiating clinical feature in comparison to narcolepsy patients without psychosis. Narcolepsy therapy may have played a role in triggering psychotic symptoms but these did not reverse with changes in narcolepsy medications. Response to antipsychotic treatment was variable. Pathophysiological studies did not reveal any known autoantibodies or unusual brain immunostaining pattern. No strong HLA association outside of HLA DQB1*06:02 was found, although increased DRB3*03 and DPA1*02:01 was notable.
CONCLUSION: Narcolepsy can occur in association with schizophrenia, with significant diagnostic and therapeutic challenges. Dual cases maybe under diagnosed, as onset is unusually early, often in childhood. Narcolepsy and psychosis may share an autoimmune pathology; thus, further investigations in larger samples are warranted.