title: Effects of education on the progression of early- versus late-stage mild cognitive impairment.
abstract: BACKGROUND
  Highly educated participants with normal cognition show lower incidence of Alzheimer's disease (AD) than poorly educated participants, whereas longitudinal studies involving AD have reported that higher education is associated with more rapid cognitive decline. We aimed to evaluate whether highly educated amnestic mild cognitive impairment (aMCI) participants show more rapid cognitive decline than those with lower levels of education.
  
  
  METHODS
  A total of 249 aMCI patients enrolled from 31 memory clinics using the standard assessment and diagnostic processes were followed with neuropsychological evaluation (duration 17.2 ± 8.8 months). According to baseline performances on memory tests, participants were divided into early-stage aMCI (-1.5 to -1.0 standard deviation (SD)) and late-stage aMCI (below -1.5 SD) groups. Risk of AD conversion and changes in neuropsychological performances according to the level of education were evaluated.
  
  
  RESULTS
  Sixty-two patients converted to AD over a mean follow-up of 1.43 years. The risk of AD conversion was higher in late-stage aMCI than early-stage aMCI. Cox proportional hazard models showed that aMCI participants, and late-stage aMCI participants in particular, with higher levels of education had a higher risk of AD conversion than those with lower levels of education. Late-stage aMCI participants with higher education showed faster cognitive decline in language, memory, and Clinical Dementia Rating Sum of Boxes (CDR-SOB) scores. On the contrary, early-stage aMCI participants with higher education showed slower cognitive decline in MMSE and CDR-SOB scores.
  
  
  CONCLUSIONS
  Our findings suggest that the protective effects of education against cognitive decline remain in early-stage aMCI and disappear in late-stage aMCI.
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Byoung Seok
authors.initials: BS
authors.lastname: Ye
authors.forename: Sang Won
authors.initials: SW
authors.lastname: Seo
authors.forename: Hanna
authors.initials: H
authors.lastname: Cho
authors.forename: Seong Yoon
authors.initials: SY
authors.lastname: Kim
authors.forename: Jung-Sun
authors.initials: JS
authors.lastname: Lee
authors.forename: Eun-Joo
authors.initials: EJ
authors.lastname: Kim
authors.forename: Yunhwan
authors.initials: Y
authors.lastname: Lee
authors.forename: Joung Hwan
authors.initials: JH
authors.lastname: Back
authors.forename: Chang Hyung
authors.initials: CH
authors.lastname: Hong
authors.forename: Seong Hye
authors.initials: SH
authors.lastname: Choi
authors.forename: Kyung Won
authors.initials: KW
authors.lastname: Park
authors.forename: Bon D
authors.initials: BD
authors.lastname: Ku
authors.forename: So Young
authors.initials: SY
authors.lastname: Moon
authors.forename: Sangyun
authors.initials: S
authors.lastname: Kim
authors.forename: Seol-Heui
authors.initials: SH
authors.lastname: Han
authors.forename: Jae-Hong
authors.initials: JH
authors.lastname: Lee
authors.forename: Hae-Kwan
authors.initials: HK
authors.lastname: Cheong
authors.forename: Duk L
authors.initials: DL
authors.lastname: Na
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000523:psychology; D000647:Amnesia / Q000523:psychology*; D003072:Cognition Disorders / Q000175:diagnosis / Q000523:psychology*; D060825:Cognitive Dysfunction / Q000175:diagnosis / Q000523:psychology*; D018450:Disease Progression; D004522:Educational Status; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D009483:Neuropsychological Tests; D016016:Proportional Hazards Models; D011569:Psychiatric Status Rating Scales; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D013997:Time Factors