br Discussion Results from this general

Discussion Results from this general health status measure suggest that narcolepsy substantially impairs function, psychosocial more than physical. The impact of this disease on patients׳ daily lives may be underappreciated because the relatively preserved physical function gives others the impression that patients with narcolepsy are healthy or do not have a serious disease. Among patients with cataplexy, the impairment of function was greater. On the other hand, among patients with HLA DQB1⁎0602 positivity, the impairment of function was less. Whether cataplexy and HLA status identify subtypes of narcolepsy with possibly different etiologies remains to be determined. Recent publications have raised questions about the importance of cataplexy. In one, partial loss of hypocretin (orexin) available was documented on neuropathologic examination in narcolepsy without cataplexy [15]. In another, a subset of patients with hypersomnia who did not meet criteria for narcolepsy had the same genetic profile described in patients with narcolepsy with cataplexy, namely positivity for HLA DQB1⁎0602 and T-cell receptor alpha (TCRA) locus [16]. The ESS and the UNS focus on clinical features. The ESS assesses sleepiness, while the UNS includes questions about cataplexy, perhaps explaining why correlations with the SIP were stronger for UNS than the ESS. Although these scales were correlated with the SIP, the correlation was not perfect suggesting that the SIP may be capturing other information about the impact of the disease on a person׳s function and providing a richer description of narcolepsy׳s profile. The SIP also allows comparison across diseases, although caution is needed because of the differences in populations studied. The mean overall SIP score in these patients was 10.3. The comparable figure was 3.6 in a general population; 15.6 in a clinic-based series of patients with rheumatoid arthritis [10]; and 16.8 in a clinic-based series of patients with Parkinson׳s disease [8]. The Psychosocial Dimension score was 13.2 with narcolepsy, 11.3 with rheumatoid arthritis, 19.4 with Parkinson׳s disease. Many of the items endorsed in the SIP could be anticipated based on the key clinical feature of excessive daytime sleepiness. Less easily explained is that over a third of patients endorsed sexual and memory dysfunction. Sexual dysfunction has been noted previously [17] but not emphasized in descriptions of the disease. Although memory has been found to be preserved on neuropsychological testing, despite complaints of memory problems, executive function may be impaired in patients with narcolepsy [18]. Whether these dysfunctions relate to sleep deprivation, some direct effect of narcolepsy, or some medication side effect cannot be determined by sperm study, but the issue of cause deserves further consideration. Interventions aimed at improving these dysfunctions may improve the quality of life for patients with narcolepsy. Although the study was population-based, we did not recruit all patients with physician-diagnosed narcolepsy into the full study so the responses of those who participated may have differed from those who did not participate. We did not perform standardized sleep studies in all patients, but the region׳s sleep medicine experts made most of the diagnoses [12], and our results were similar when restricted to patients with cataplexy. We also did not have biological specimens beyond DNA in these patients, such as hypocretin-1 levels in the cerebrospinal fluid. This study was cross-sectional, and longitudinal studies would be needed to judge the responsiveness of the SIP to changes judged important by the patients and providers.
Financial support The National Institute of Neurological Disorders and Stroke funded this study (NS038523).
Declaration of interest
Acknowledgments
Introduction Parkinson׳s disease (PD) presents with classical motor manifestations that include tremor, rigidity, akinesia and postural instability [1,2]. Several non-motor abnormalities, including sleep alterations, such as, excessive daytime sleepiness (EDS), “sleep attacks” or episodes of sudden onset of sleep (SOS), insomnia, restless legs syndrome and rapid eye movement sleep behavior disorder (RBD) have been described [3,4]. Importantly, EDS and SOS episodes greatly affect patients and caregiver׳s routine and potentially increase the risk of accidents [5]. To date, these alterations remain a challenge to treatment as there is not enough evidence to make a recommendation for the management of these sleep-wake abnormalities [6]. Possibly, sleep and wake abnormalities contribute to the heterogeneous clinical manifestations of PD and to the common daytime oscillations of symptoms. Thus, modifying factors that influence EDS and SOS episodes may contribute to improve therapy.