Phenotyping apathy in individuals with Alzheimer disease using functional principal component analysis

Am J Geriatr Psychiatry. 2013 Apr;21(4):391-7. doi: 10.1016/j.jagp.2012.12.012. Epub 2013 Feb 6.


Objectives: To determine if there is a specific pattern of gross motor activity associated with apathy in individuals with Alzheimer disease (AD).

Design: Examination of ad libitum 24-hour ambulatory gross motor activity patterns.

Setting: Community-dwelling, outpatient.

Participants: Ninety-two individuals with AD, 35 of whom had apathy.

Measurements: 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Actigraphy
  • Aged
  • Aged, 80 and over
  • Alzheimer Disease / complications
  • Alzheimer Disease / physiopathology*
  • Alzheimer Disease / psychology*
  • Apathy*
  • Circadian Rhythm / physiology
  • Depression / complications
  • Depression / physiopathology
  • Depression / psychology
  • Female
  • Humans
  • Male
  • Motor Activity / physiology
  • Principal Component Analysis*
  • Sleep