Attentive and preattentive processing in narcolepsy as revealed by event-related potentials (ERPs)

Narcolepsy is a neurological disorder, characterised by excessive daytime sleepiness, sleep attacks, cataplexy and abnormal manifestations of rapid eye movement sleep. Recent studies suggest that neuropsychological impairments in narcolepsy may include memory and attention deficits due to a monoaminergic or cholinergic transmitter dysfunction. To explore the nature of cognitive problems, the P300 and mismatch negativity (MMN) event-related potentials were investigated in narcoleptic patients and matched controls. Narcoleptics showed significantly increased P300 amplitudes relative to controls, especially at frontal recording sites. While control subjects exhibited typically larger MMN over the right than the left hemisphere, in particular at frontal and central electrodes, narcoleptics did not show this asymmetry. These results are interpreted as possible alterations in cognitive preattentive and attentive processing associated with altered functioning of the prefrontal cortex in narcolepsy.