title: The timing of activity rhythms in patients with dementia is related to survival.
abstract: BACKGROUND
  Older adults with dementia often have disruptions in circadian rhythms, including disruptions of the rest-activity rhythm. These disruptions are a product of internal neuronal activity and external environmental influences, both of which are deficient in dementia. However, the consequences of disturbed rhythms are unknown. This study examined the relationship between rest-activity rhythms and death in patients with dementia.
  
  
  METHODS
  The authors recruited 149 older adults with dementia (104 women; mean age, 84.1 years) from nursing homes. Activity was recorded with wrist actigraphs from each participant for 3 days. Survival was determined by examining public death records. Cox proportional hazards models were used to determine which aspects of rest-activity rhythms were related to survival.
  
  
  RESULTS
  The timing of each participant's rest-activity rhythm compared with a sample of persons without dementia was related to survival, such that those who more closely resembled the persons without dementia lived longer.
  
  
  CONCLUSIONS
  Although rest-activity rhythms as a whole were not related to survival, the timing of the rhythm was. Patients with dementia appear to develop an abnormal timing of their rhythms, which is predictive of shorter survival. It may be possible to intervene with these patients to correct the timing of their rhythms and possibly prolong their lives.
authors.affiliation: SDSU/UCSD Joint Doctoral Program in Clinical Psychology, Department of Psychiatry, University of California, San Diego, USA.
authors.forename: Phil
authors.initials: P
authors.lastname: Gehrman
authors.forename: Matthew
authors.initials: M
authors.lastname: Marler
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Martin
authors.forename: Tamar
authors.initials: T
authors.lastname: Shochat
authors.forename: Jody
authors.initials: J
authors.lastname: Corey-Bloom
authors.forename: Sonia
authors.initials: S
authors.lastname: Ancoli-Israel
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000401:mortality* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008136:Longevity; D008297:Male; D008875:Middle Aged; D009068:Movement; D010507:Periodicity; D012146:Rest; D016019:Survival Analysis; D013997:Time Factors