title: Exercise Training and Functional Connectivity Changes in Mild Cognitive Impairment and Healthy Elders.
abstract: Effective interventions are needed to improve brain function in mild cognitive impairment (MCI), an early stage of Alzheimer's disease (AD). The posterior cingulate cortex (PCC)/precuneus is a hub of the default mode network (DMN) and is preferentially vulnerable to disruption of functional connectivity in MCI and AD.
  
  
  
  We investigated whether 12 weeks of aerobic exercise could enhance functional connectivity of the PCC/precuneus in MCI and healthy elders.
  
  
  
  Sixteen MCI and 16 healthy elders (age range = 60-88) engaged in a supervised 12-week walking exercise intervention. Functional MRI was acquired at rest; the PCC/precuneus was used as a seed for correlated brain activity maps.
  
  
  
  A linear mixed effects model revealed a significant interaction in the right parietal lobe: the MCI group showed increased connectivity while the healthy elders showed decreased connectivity. In addition, both groups showed increased connectivity with the left postcentral gyrus. Comparing pre to post intervention changes within each group, the MCI group showed increased connectivity in 10 regions spanning frontal, parietal, temporal and insular lobes, and the cerebellum. Healthy elders did not demonstrate any significant connectivity changes.
  
  
  
  The observed results show increased functional connectivity of the PCC/precuneus in individuals with MCI after 12 weeks of moderate intensity walking exercise training. The protective effects of exercise training on cognition may be realized through the enhancement of neural recruitment mechanisms, which may possibly increase cognitive reserve. Whether these effects of exercise training may delay further cognitive decline in patients diagnosed with MCI remains to be demonstrated.
authors.affiliation: University of Maryland, College Park, MD, USA.
authors.forename: Theresa J
authors.initials: TJ
authors.lastname: Chirles
authors.affiliation: Marquette University, Milwaukee, WI, USA.
authors.forename: Katherine
authors.initials: K
authors.lastname: Reiter
authors.affiliation: University of Maryland, College Park, MD, USA.
authors.forename: Lauren R
authors.initials: LR
authors.lastname: Weiss
authors.affiliation: University of Maryland, College Park, MD, USA.
authors.forename: Alfonso J
authors.initials: AJ
authors.lastname: Alfini
authors.affiliation: Marquette University, Milwaukee, WI, USA.|Medical College of Wisconsin, Milwaukee, WI, USA.
authors.forename: Kristy A
authors.initials: KA
authors.lastname: Nielson
authors.affiliation: University of Maryland, College Park, MD, USA.
authors.forename: J Carson
authors.initials: JC
authors.lastname: Smith
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D060825:Cognitive Dysfunction / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000534:rehabilitation*; D015444:Exercise; D005080:Exercise Test; D005260:Female; D006179:Gyrus Cinguli / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D011569:Psychiatric Status Rating Scales
chemical_list: D010100:Oxygen
keywords: Aging; Alzheimer’s disease; cognitive disorders; connectivity; default mode network; exercise intervention; neural plasticity; posterior cingulate; precuneus; resting state functional MRI