The aim of this study was to investigate the influence of age on the manifestation of narcolepsy symptoms and cognitive difficulties in patients with narcolepsy.
Methods
A total of 321 participants were included in the study: 157 were patients with narcolepsy from two Sleep Disorders Clinics and 164 were control participants. Narcoleptic patients were evaluated and diagnosed at the Sleep Disorders Clinic. All participants were interviewed by telephone using the Sleep-EVAL System. The interview comprised, among else, a detailed evaluation of narcolepsy symptoms and of cognitive difficulties.
Results
The first manifestation of the disease appeared early in life for most narcoleptic patients: 54.1% had their first symptom before the age of 20 years. Daytime sleepiness was the first symptom to appear in 65.5% of cases. In narcoleptics 60 years or older, cataplexy was more likely to be the first symptom to appear (47.4%) compared with other narcoleptic patients (21.4%; P<.05). Reported cognitive difficulties (attention–concentration, praxis, delay recall, orientation for persons, temporal orientation, and prospective memory) were higher in narcoleptic patients compared with the controls. The severity of daytime sleepiness and the presence of a major depressive disorder partly explained the cognitive difficulties. However, attention–concentration deficits and difficulties in prospective memory remained significant. Age was unrelated to cognitive difficulties in narcoleptics patients.
Conclusions
The first manifestation of narcolepsy appears early in life. Reported cognitive difficulties are important in narcoleptic patients and are only partly explained by age, severity of daytime sleepiness, and major depressive disorder.
aStanford Sleep Epidemiology Research Center, School of Medicine, Stanford University, Stanford, CA, USA
bSleep Disorders Center, Università Vita e Salute San Raffaele, Milan, Italy
cInstitute of Clinical Neurology, University of Bologna, Bologna, Italy
dSleep Medicine Centre, State University and Istituto Ortopedico Galeazzi, Milano, Italy
Corresponding author. Stanford Sleep Epidemiology Research Center, School of Medicine, Stanford University, Suite 102, 3430 W. Bayshore Road, Palo Alto, CA 94303, USA. Tel.: +1 650 494 1137; fax: +1 650 947 9813, +1 650 493 1225
ABSTRACT