title: Hippocampal volume and memory in narcoleptics with cataplexy.
abstract: OBJECTIVE
  The objective of this study was to investigate the differences in hippocampal volume (HV) between narcoleptics and normal controls and determine if HV is associated with memory function in narcoleptics. Left and right HV and intracranial volumes (ICV) were manually measured and compared between two groups.
  
  
  METHODS
  The study consisted of 36 drug-naïve narcoleptics with cataplexy and 36 age- and sex-matched controls (mean age 29.0 years). All subjects underwent 1.6-mm-thick spoiled gradient recalled magnetic resonance imaging and took the Korean California Verbal Learning Test and the Rey Complex Figure Test to assess verbal and visual memory.
  
  
  RESULTS
  The mean ICV was not different between groups (1599.2 cm(3) in narcoleptics vs. 1623.5 cm(3) in controls, p = .450). Bilateral mean HVs were significantly smaller in narcoleptics (left, 2907.2mm(3) in narcoleptics vs. 3092.3mm(3) in controls, p = 0.005; right, 2990.8mm(3) in narcoleptics vs. 3184.3mm(3) in controls, p = 0.004). Significance of HV differences between groups remained after corrections were made for gender, age, and ICV. In narcoleptics, bilateral HV was positively correlated with mean sleep and REM sleep latencies in Multiple Sleep Latency Tests. Absolute memory scores were not different between groups and were not correlated with HV in narcoleptics.
  
  
  CONCLUSIONS
  Narcoleptics had smaller bilateral HVs compared to controls. HV had a significant relationship with sleep and REM sleep latencies. This study provides supportive evidence of the functional and anatomical deficits in medial temporal areas that are related to the severity of narcolepsy.
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Eun Yeon
authors.initials: EY
authors.lastname: Joo
authors.forename: Sun Hwa
authors.initials: SH
authors.lastname: Kim
authors.forename: Sung-Tae
authors.initials: ST
authors.lastname: Kim
authors.forename: Seung Bong
authors.initials: SB
authors.lastname: Hong
mesh_terms: D000328:Adult; D000339:Affect; D005260:Female; D007839:Functional Laterality; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory; D008569:Memory Disorders / Q000473:pathology*; D009290:Narcolepsy / Q000473:pathology*; D007319:Sleep Initiation and Maintenance Disorders / Q000473:pathology; D012895:Sleep, REM; D014706:Verbal Learning