title: The characterization of biological rhythms in mild cognitive impairment.
abstract: BACKGROUND
  Patients with dementia, especially Alzheimer's disease, present several circadian impairments related to an accelerated perturbation of their biological clock that is caused by the illness itself and not merely age-related. Thus, the objective of this work was to elucidate whether these circadian system alterations were already present in patients with mild cognitive impairment (MCI), as compared to healthy age-matched subjects.
  
  
  METHODS
  40 subjects (21 patients diagnosed with MCI, 74.1 ± 1.5 y.o., and 19 healthy subjects, 71.7 ± 1.4 y.o.) were subjected to ambulatory monitoring, recording wrist skin temperature, motor activity, body position, and the integrated variable TAP (including temperature, activity, and position) for one week. Nonparametrical analyses were then applied.
  
  
  RESULTS
  MCI patients exhibited a significant phase advance with respect to the healthy group for the following phase markers: temperature M5 (mean ± SEM: 04:20 ± 00:21 versus 02:52 ± 00:21) and L10 (14:35 ± 00:27 versus 13:24 ± 00:16) and TAP L5 (04:18 ± 00:14 versus 02:55 ± 00:30) and M10 (14:30 ± 00:18 versus 13:28 ± 00:23).
  
  
  CONCLUSIONS
  These results suggest that significant advances in the biological clock begin to occur in MCI patients, evidenced by an accelerated aging of the circadian clock, as compared to a healthy population of the same age.
authors.affiliation: Chronobiology Laboratory, Department of Physiology, Faculty of Biology, University of Murcia, Campus de Espinardo, Espinardo, 30100 Murcia, Spain.
authors.forename: Elisabet
authors.identifier: 0000-0002-4795-8860
authors.initials: E
authors.lastname: Ortiz-Tudela
authors.affiliation: Chronobiology Laboratory, Department of Physiology, Faculty of Biology, University of Murcia, Campus de Espinardo, Espinardo, 30100 Murcia, Spain.
authors.forename: Antonio
authors.identifier: 0000-0002-8213-3370
authors.initials: A
authors.lastname: Martinez-Nicolas
authors.affiliation: Department of Basic Psychology, Universidad Nacional de Educación a Distancia (UNED), 28040 Madrid, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Díaz-Mardomingo
authors.affiliation: Department of Basic Psychology, Universidad Nacional de Educación a Distancia (UNED), 28040 Madrid, Spain.
authors.forename: Sara
authors.initials: S
authors.lastname: García-Herranz
authors.affiliation: Department of Psychobiology, Universidad Nacional de Educación a Distancia (UNED), 28040 Madrid, Spain.
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Pereda-Pérez
authors.affiliation: Department of Psychobiology, Universidad Nacional de Educación a Distancia (UNED), 28040 Madrid, Spain.
authors.forename: Azucena
authors.identifier: 0000-0003-0821-7805
authors.initials: A
authors.lastname: Valencia
authors.affiliation: Department of Basic Psychology, Universidad Nacional de Educación a Distancia (UNED), 28040 Madrid, Spain.
authors.forename: Herminia
authors.initials: H
authors.lastname: Peraita
authors.affiliation: Department of Psychobiology, Universidad Nacional de Educación a Distancia (UNED), 28040 Madrid, Spain.
authors.forename: César
authors.initials: C
authors.lastname: Venero
authors.affiliation: Chronobiology Laboratory, Department of Physiology, Faculty of Biology, University of Murcia, Campus de Espinardo, Espinardo, 30100 Murcia, Spain.
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: Madrid
authors.affiliation: Chronobiology Laboratory, Department of Physiology, Faculty of Biology, University of Murcia, Campus de Espinardo, Espinardo, 30100 Murcia, Spain.
authors.forename: Maria Angeles
authors.initials: MA
authors.lastname: Rol
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D002940:Circadian Rhythm; D060825:Cognitive Dysfunction / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D018709:Statistics, Nonparametric