title: Early dysfunction of functional connectivity in healthy elderly with subjective memory complaints.
abstract: It is still an open question whether subjective memory complaints (SMC) can actually be considered to be clinically relevant predictors for the development of an objective memory impairment and even dementia. There is growing evidence that suggests that SMC are associated with an increased risk of dementia and with the presence of biological correlates of early Alzheimer's disease. In this paper, in order to shed some light on this issue, we try to discern whether subjects with SMC showed a different profile of functional connectivity compared with subjects with mild cognitive impairment (MCI) and healthy elderly subjects. In the present study, we compare the degree of synchronization of brain signals recorded with magnetoencephalography between three groups of subjects (56 in total): 19 with MCI, 12 with SMC and 25 healthy controls during a memory task. Synchronization likelihood, an index based on the theory of nonlinear dynamical systems, was used to measure functional connectivity. Briefly, results show that subjects with SMC have a very similar pattern of connectivity to control group, but on average, they present a lower synchronization value. These results could indicate that SMC are representing an initial stage with a hypo-synchronization (in comparison with the control group) where the brain system is still not compensating for the failing memory networks, but behaving as controls when compared with the MCI subjects.
authors.affiliation: Laboratory of Cognitive and Computational Neuroscience, Centre for Biomedical Technology, Madrid, Spain. rbbreton@estumail.ucm.es
authors.forename: Ricardo
authors.initials: R
authors.lastname: Bajo
authors.forename: Nazareth P
authors.initials: NP
authors.lastname: Castellanos
authors.forename: Maria Eugenia
authors.initials: ME
authors.lastname: López
authors.forename: José María
authors.initials: JM
authors.lastname: Ruiz
authors.forename: Pedro
authors.initials: P
authors.lastname: Montejo
authors.forename: Mercedes
authors.initials: M
authors.lastname: Montenegro
authors.forename: Marcos
authors.initials: M
authors.lastname: Llanero
authors.forename: Pedro
authors.initials: P
authors.lastname: Gil
authors.forename: Raquel
authors.initials: R
authors.lastname: Yubero
authors.forename: Evgenia
authors.initials: E
authors.lastname: Baykova
authors.forename: Nuria
authors.initials: N
authors.lastname: Paul
authors.forename: Sara
authors.initials: S
authors.lastname: Aurtenetxe
authors.forename: Francisco
authors.initials: F
authors.lastname: Del Pozo
authors.forename: Fernando
authors.initials: F
authors.lastname: Maestu
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D001921:Brain / Q000503:physiopathology*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008568:Memory / Q000502:physiology*; D008569:Memory Disorders / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D009483:Neuropsychological Tests