title: Fasting plasma insulin and the default mode network in women at risk for Alzheimer's disease.
abstract: Brain imaging studies in Alzheimer's disease research have demonstrated structural and functional perturbations in the hippocampus and default mode network (DMN). Additional evidence suggests risk for pathological brain aging in association with insulin resistance (IR). This study piloted investigation of associations of IR with DMN-hippocampal functional connectivity among postmenopausal women at risk for Alzheimer's disease. Twenty middle-aged women underwent resting state functional magnetic resonance imaging. Subjects were dichotomized relative to fasting plasma insulin levels (i.e., > 8 μIU/mL [n = 10] and < 8 μIU/mL [n = 10]), and functional connectivity analysis contrasted their respective blood oxygen level-dependent signal correlation between DMN and hippocampal regions. Higher-insulin women had significantly reduced positive associations between the medial prefrontal cortex and bilateral parahippocampal regions extending to the right hippocampus, and conversely, between the left and right hippocampus and medial prefrontal cortex. Neuropsychological data (all within normal ranges) also showed significant differences with respect to executive functioning and global intelligence. The results provide further evidence of deleterious effects of IR on the hippocampus and cognition. Further imaging studies of the IR-related perturbations in DMN-hippocampal functional connectivity are needed.
authors: Stanford Center for Neurosciences in Women's Health, Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 95305-5723, USA.
authors: Heather
authors: H
authors: Kenna
authors: Fumiko
authors: F
authors: Hoeft
authors: Ryan
authors: R
authors: Kelley
authors: Tonita
authors: T
authors: Wroolie
authors: Bevin
authors: B
authors: DeMuth
authors: Allan
authors: A
authors: Reiss
authors: Natalie
authors: N
authors: Rasgon
mesh_terms: D000544:Alzheimer Disease / Q000097:blood / Q000503:physiopathology; D001931:Brain Mapping; D056344:Executive Function; D005215:Fasting / Q000097:blood*; D005260:Female; D059907:Functional Neuroimaging; D006624:Hippocampus / Q000503:physiopathology*; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009434:Neural Pathways; D009483:Neuropsychological Tests; D010865:Pilot Projects; D017698:Postmenopause / Q000097:blood; D017397:Prefrontal Cortex / Q000503:physiopathology*; D012307:Risk Factors
chemical_list: D007328:Insulin