title: Higher risk of progression to dementia in mild cognitive impairment cases who revert to normal.
abstract: OBJECTIVE
  To estimate rates of progression from mild cognitive impairment (MCI) to dementia and of reversion from MCI to being cognitively normal (CN) in a population-based cohort.
  
  
  METHODS
  Participants (n = 534, aged 70 years and older) enrolled in the prospective Mayo Clinic Study of Aging were evaluated at baseline and every 15 months to identify incident MCI or dementia.
  
  
  RESULTS
  Over a median follow-up of 5.1 years, 153 of 534 participants (28.7%) with prevalent or incident MCI progressed to dementia (71.3 per 1,000 person-years). The cumulative incidence of dementia was 5.4% at 1 year, 16.1% at 2, 23.4% at 3, 31.1% at 4, and 42.5% at 5 years. The risk of dementia was elevated in MCI cases (hazard ratio [HR] 23.2, p < 0.001) compared with CN subjects. Thirty-eight percent (n = 201) of MCI participants reverted to CN (175.0/1,000 person-years), but 65% subsequently developed MCI or dementia; the HR was 6.6 (p < 0.001) compared with CN subjects. The risk of reversion was reduced in subjects with an APOE ε4 allele (HR 0.53, p < 0.001), higher Clinical Dementia Rating Scale-Sum of Boxes (HR 0.56, p < 0.001), and poorer cognitive function (HR 0.56, p < 0.001). The risk was also reduced in subjects with amnestic MCI (HR 0.70, p = 0.02) and multidomain MCI (HR 0.61, p = 0.003).
  
  
  CONCLUSIONS
  MCI cases, including those who revert to CN, have a high risk of progressing to dementia. This suggests that diagnosis of MCI at any time has prognostic value.
authors.affiliation: From the Divisions of Epidemiology (R.O.R., M.M.M., Y.E.G., W.A.R., R.C.P) and Biomedical Statistics and Informatics (R.H.C. V.S.P., T.J.H.C.), Department of Health Sciences Research; Department of Neurology (R.O.R., D.S.K., B.F.B., R.C.P.); Department of Psychiatry and Psychology (R.J.I.); and Division of Primary Care Internal Medicine, Department of Internal Medicine (E.G.T), Mayo Clinic, Rochester, MN; and Departments of Psychiatry & Psychology and Neurology (Y.E.G.), Mayo Clinic, Scottsdale, AZ.
authors.forename: Rosebud O
authors.initials: RO
authors.lastname: Roberts
authors.forename: David S
authors.initials: DS
authors.lastname: Knopman
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Mielke
authors.forename: Ruth H
authors.initials: RH
authors.lastname: Cha
authors.forename: V Shane
authors.initials: VS
authors.lastname: Pankratz
authors.forename: Teresa J H
authors.initials: TJ
authors.lastname: Christianson
authors.forename: Yonas E
authors.initials: YE
authors.lastname: Geda
authors.forename: Bradley F
authors.initials: BF
authors.lastname: Boeve
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Ivnik
authors.forename: Eric G
authors.initials: EG
authors.lastname: Tangalos
authors.forename: Walter A
authors.initials: WA
authors.lastname: Rocca
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Petersen
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001057:Apolipoproteins E / Q000235:genetics; D060825:Cognitive Dysfunction / Q000453:epidemiology* / Q000503:physiopathology*; D015331:Cohort Studies; D018672:Community Health Planning; D003704:Dementia / Q000175:diagnosis / Q000453:epidemiology*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011569:Psychiatric Status Rating Scales; D012307:Risk Factors
chemical_list: D001057:Apolipoproteins E