title: The role of carotid intima-media thickness in predicting longitudinal cognitive function in an older adult cohort.
abstract: OBJECTIVE
  Carotid atherosclerosis is a risk factor for cerebrovascular disease in older adults. Although age-related cognitive decline has been associated with cerebrovascular disease, not much is known about the consequences of carotid atherosclerosis on longitudinal cognitive function. This study examines the longitudinal relationship between atherosclerosis and cognition in a sample of non-demented older subjects using baseline measurements of carotid intima media thickness (CIMT) and annual cognitive measures of executive function (EXEC) and verbal memory (MEM).
  
  
  METHODS
  Baseline measurements included CIMT derived from B-mode carotid artery ultrasound, structural T1-weighted images of white matter hypointensities (WMH), white matter lesions (WML), and cerebral infarct. Hypertension, low-density lipoprotein (LDL), diabetes, and waist to hip ratios (WHR) were included as covariates in our models to control for cerebrovascular risks and central adiposity. Annual composite scores of EXEC and MEM functions were derived from item response theory. Linear mixed models were used to model longitudinal cognitive change.
  
  
  RESULTS
  A significant inverse relationship was found between baseline CIMT and annual EXEC score, but not annual MEM score. Subjects included in the highest 4th quartile of CIMT showed a rate of annual decline in EXEC score that was significant relative to subjects in lower quartile groups (p<0.01). The relationship between the 4th quartile of CIMT and annual EXEC score remained significant after independently adjusting for imaging measures of white matter injury and cerebral infarct.
  
  
  CONCLUSIONS
  Older adult subjects with the highest index of CIMT showed an annual decline in EXEC scores that was significant relative to subjects with lower quartile measurements of CIMT, independent of our measures of white matter injury and cerebral infarct. Our findings suggest that elevated measures of CIMT may mark an atherosclerotic state, resulting in a decline in executive function and not memory in non-demented older adults.
authors.affiliation: Memory and Aging Center, San Francisco, Calif., USA.
authors.forename: Darvis T
authors.initials: DT
authors.lastname: Frazier
authors.forename: Talia
authors.initials: T
authors.lastname: Seider
authors.forename: Brianne M
authors.initials: BM
authors.lastname: Bettcher
authors.forename: Wendy J
authors.initials: WJ
authors.lastname: Mack
authors.forename: Laura
authors.initials: L
authors.lastname: Jastrzab
authors.forename: Linda
authors.initials: L
authors.lastname: Chao
authors.forename: Michael W
authors.initials: MW
authors.lastname: Weiner
authors.forename: Charles
authors.initials: C
authors.lastname: DeCarli
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Reed
authors.forename: Dan
authors.initials: D
authors.lastname: Mungas
authors.forename: Helena C
authors.initials: HC
authors.lastname: Chui
authors.forename: Joel H
authors.initials: JH
authors.lastname: Kramer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging / Q000453:epidemiology*; D059168:Carotid Intima-Media Thickness; D003071:Cognition; D003072:Cognition Disorders / Q000453:epidemiology* / Q000473:pathology; D056344:Executive Function; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests; D011446:Prospective Studies; D066127:White Matter / Q000473:pathology*