Psychotic symptoms in narcolepsy: phenomenology and a comparison with schizophrenia.
OBJECTIVE
Patients with narcolepsy often experience pervasive hypnagogic hallucinations, sometimes even leading to confusion with schizophrenia. We aimed to provide a detailed qualitative description of hypnagogic hallucinations and other "psychotic" symptoms in patients with narcolepsy and contrast these with schizophrenia patients and healthy controls. We also compared the prevalence of formal psychotic disorders between narcolepsy patients and controls.


METHODS
We used SCAN 2.1 interviews to compare psychotic symptoms between 60 patients with narcolepsy, 102 with schizophrenia and 120 matched population controls. In addition, qualitative data was collected to enable a detailed description of hypnagogic hallucinations in narcolepsy.


RESULTS
There were clear differences in the pattern of hallucinatory experiences in narcolepsy vs. schizophrenia patients. Narcoleptics reported multisensory "holistic" hallucinations rather than the predominantly verbal-auditory sensory mode of schizophrenia patients. Psychotic symptoms such as delusions were not more frequent in narcolepsy compared to population controls. In addition, the prevalence of formal psychotic disorders was not increased in patients with narcolepsy. Almost half of narcoleptics reported moderate interference with functioning due to hypnagogic hallucinations, mostly due to related anxiety.


CONCLUSIONS
Hypnagogic hallucinations in narcolepsy can be differentiated on a phenomenological basis from hallucinations in schizophrenia which is useful in differential diagnostic dilemmas.
Fortuyn
Hal A Droogleever
HA
Department of Psychiatry, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands. h.droogleever-fortuyn@psy.umcn.nl
Lappenschaar
G A
GA
Nienhuis
Fokko J
FJ
Furer
Joop W
JW
Hodiamont
Paul P
PP
Rijnders
Cees A
CA
Lammers
Gert Jan
GJ
Renier
Willy O
WO
Buitelaar
Jan K
JK
Overeem
Sebastiaan
S
D000328:Adult; D003430:Cross-Sectional Studies; D003702:Delusions / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D006212:Hallucinations / Q000175:diagnosis / Q000453:epidemiology; D006801:Humans; D008297:Male; D009290:Narcolepsy / Q000453:epidemiology*; D015995:Prevalence; D011618:Psychotic Disorders / Q000175:diagnosis* / Q000453:epidemiology*; D012559:Schizophrenia / Q000175:diagnosis* / Q000453:epidemiology*