title: Phenotyping apathy in individuals with Alzheimer disease using functional principal component analysis.
abstract: OBJECTIVE
  To determine if there is a specific pattern of gross motor activity associated with apathy in individuals with Alzheimer disease (AD).
  
  
  METHODS
  Examination of ad libitum 24-hour ambulatory gross motor activity patterns.
  
  
  METHODS
  Community-dwelling, outpatient.
  
  
  METHODS
  Ninety-two individuals with AD, 35 of whom had apathy.
  
  
  METHODS
  Wrist actigraphy data were collected and examined using functional principal component analysis (fPCA).
  
  
  RESULTS
  Individuals with apathy have a different pattern of gross motor activity than those without apathy (first fPCA component, p <0.0001, t = 5.73, df = 90, t test) such that there is a pronounced decline in early afternoon activity in those with apathy. This change in activity is independent of depression (p = 0.68, F[1, 89] = 0.05, analysis of variance). The decline in activity is consistent with an increase in napping. Those with apathy also have an early wake and bedtime (second fPCA component, t = 2.53, df = 90, p <0.05, t test).
  
  
  CONCLUSIONS
  There is a signature activity pattern in individuals with apathy and AD that is distinct from those without apathy and those with depression. Actigraphy may be a useful adjunctive measurement in the clinical diagnosis of apathy in the context of AD.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Stanford University, Palo Alto, CA; Psychiatry Service, Veterans Affairs Palo Alto Health Care System, Palo Alto, CA. Electronic address: jzeitzer@stanford.edu.
authors.forename: Jamie M
authors.initials: JM
authors.lastname: Zeitzer
authors.forename: Renaud
authors.initials: R
authors.lastname: David
authors.forename: Leah
authors.initials: L
authors.lastname: Friedman
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Mulin
authors.forename: René
authors.initials: R
authors.lastname: Garcia
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.forename: Jerome A
authors.initials: JA
authors.lastname: Yesavage
authors.forename: Philippe H
authors.initials: PH
authors.lastname: Robert
authors.forename: William
authors.initials: W
authors.lastname: Shannon
mesh_terms: D056044:Actigraphy; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000150:complications / Q000503:physiopathology* / Q000523:psychology*; D057565:Apathy; D002940:Circadian Rhythm / Q000502:physiology; D003863:Depression / Q000150:complications / Q000503:physiopathology / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology; D025341:Principal Component Analysis; D012890:Sleep