title: Working memory deficit in patients with restless legs syndrome: an event-related potential study.
abstract: OBJECTIVE
  The aim of this study was to investigate whether there is a working memory (WM) deficit in restless legs syndrome (RLS) patients, by studying the Sternberg WM task of event-related potential (ERP).
  
  
  METHODS
  Thirteen drug-naive RLS patients and 13 healthy age-matched controls with no sleep disturbances participated in the present study. P300 ERP was recorded during Sternberg WM task using digits as mnemonic items. P300 amplitudes and reaction times were compared between groups (RLS vs. control) considering brain regions (frontal, central, and parietal) and memory load sizes (two, three, and four) as within-subject factors. Clinical and sleep-related variables were correlated with P300 amplitude.
  
  
  RESULTS
  The reaction time in RLS patients was significantly longer than controls over all memory load sizes. The P300 amplitude at parietal regions in RLS patients was significantly lower than in controls regardless of memory load sizes, which was significantly negatively correlated with duration of RLS history in RLS patients.
  
  
  CONCLUSIONS
  Our study suggests that patients with severe RLS have WM deficits. Furthermore, negative correlation of P300 amplitudes with the duration of RLS illness suggests that cerebral cortical dysfunction in RLS patients results from repeated RLS symptom attacks.
authors.affiliation: Department of Neurology, Korea University Medical Center Anam Hospital, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Sung Min
authors.initials: SM
authors.lastname: Kim
authors.affiliation: Department of Biomedical Engineering, College of Health Science, Yonsei University, Wonju, South Korea.
authors.forename: Jeong Woo
authors.initials: JW
authors.lastname: Choi
authors.affiliation: Department of Neurology, Seoul National University College of Medicine, Seoul, South Korea.
authors.forename: Chany
authors.initials: C
authors.lastname: Lee
authors.affiliation: Department of Neurology, Seoul National University College of Medicine, Seoul, South Korea.
authors.forename: Byeong Uk
authors.initials: BU
authors.lastname: Lee
authors.affiliation: Department of Neurology, Korea University Medical Center Anam Hospital, Korea University College of Medicine, Seoul, South Korea.
authors.forename: Yong Seo
authors.initials: YS
authors.lastname: Koo
authors.affiliation: Department of Biomedical Engineering, College of Health Science, Yonsei University, Wonju, South Korea. Electronic address: khkim0604@yonsei.ac.kr.
authors.forename: Kyung Hwan
authors.initials: KH
authors.lastname: Kim
authors.affiliation: Department of Neurology, Seoul National University College of Medicine, Seoul, South Korea. Electronic address: jungky10@gmail.com.
authors.forename: Ki-Young
authors.initials: KY
authors.lastname: Jung
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000209:etiology / Q000503:physiopathology*; D008570:Memory, Short-Term / Q000502:physiology; D008875:Middle Aged; D017286:Polysomnography; D011930:Reaction Time / Q000502:physiology; D012148:Restless Legs Syndrome / Q000150:complications / Q000503:physiopathology*
keywords: Cognition disorders; Event-related potential; Frontal lobe; P300; Restless legs syndrome; Working memory