J Agric Med Community Health.  2013 Jun;38(2):97-107.

Evaluation of Cognitive Functions in Patients with Narcolepsy

Affiliations
  • 1Department of Neuropsychiatry, Chonnam National University Hospital, Korea.
  • 2Department of Neuropsychiatry, Chonnam National University Medical School, Korea.
  • 3Department of Medical Education, Chonnam National University Medical School, Korea. ekcmedu@chonnam.ac.kr

Abstract


OBJECTIVE
This study aimed to evaluate attention, memory and executive function in patients with narcolepsy.
METHODS
This study included 23 narcoleptic patients whose diagnosis were confirmed by the International Classification of Sleep Disorders(ICSD) at Chonnam National University Hospital Sleep Disorders Clinic or an other hospital in Korea, from 2005 to 2008, as well as 23 normal controls. All participants were given an IQ test for Korean-Wechsler Adult Intelligence Scale and several neuropsychological function tests (the d2 test for attention function, the Rey Complex Figure Test for nonverbal memory, the Korean-California Verbal Learning Test [K-CVLT] for verbal memory, and the Wisconsin Card Sorting Test for executive function). Clinical features of narcoleptic patients, including the frequency of excessive daytime sleepiness, cataplexy, sleep paralysis and hypnagogic hallucination, were investigated by a structured clinical interview administered by a neuropsychiatist. Excessive daytime sleepiness was evaluated by the Epworth sleepiness scale.
RESULTS
Characteristic symptoms of narcolepsy observed in this study included excessive daytime sleepiness (n=23, 100.0%), cataplexy (n=19, 82.6%), hypnagogic hallucination (n=5, 21.7%) and sleep paralysis (n=12, 52.2%). In nocturnal polysomnographic findings, stage 2 sleep and REM latency were found to be significantly decreased in narcoleptic patients compared with the control group, and were accompanied by significant increases in stage 1 sleep. Narcoleptic patients had lower scores than the control group on total number, Total Number-Total Error, Concentration Performance and Fluctuation Rate on the d2 test, which measures attention. Also, there were significant differences between the performance of patient and control groups on the B list of the K-CVLT, which measures verbal memory.
CONCLUSION
Narcoleptic patients showed decreased attention and verbal memory performance compared to the control group; however, in many areas, narcoleptic patients still demonstrated normal cognitive function.

Keyword

Narcolepsy; Cognitive aspects; Attention; Memory; Executive function

MeSH Terms

Adult
Cataplexy
Executive Function
Hallucinations
Humans
Intelligence
Korea
Memory
Narcolepsy
Sleep Paralysis
Sleep Wake Disorders
Verbal Learning
Wisconsin
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