Cited by 1,036Functional Brain Connectivity StudiesDementia and Cognitive Impairment ResearchAdvanced MRI Techniques and Applications

Selective changes of resting-state networks in individuals at risk for Alzheimer’s disease

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Sorg, Christian, Riedl, Valentin, Mühlau, Mark, Calhoun, Vince D., Eichele, Tom, Läer, Leonhard, Drzezga, Alexander, Förstl, Hans +3 more·2007·Proceedings of the National Academy of Sciences

Abstract

Alzheimer's disease (AD) is a neurodegenerative disorder that prominently affects cerebral connectivity. Assessing the functional connectivity at rest, recent functional MRI (fMRI) studies reported on the existence of resting-state networks (RSNs). RSNs are characterized by spatially coherent, spontaneous fluctuations in the blood oxygen level-dependent signal and are made up of regional patterns commonly involved in functions such as sensory, attention, or default mode processing. In AD, the default mode network (DMN) is affected by reduced functional connectivity and atrophy. In this work, we analyzed functional and structural MRI data from healthy elderly (n = 16) and patients with amnestic mild cognitive impairment (aMCI) (n = 24), a syndrome of high risk for developing AD. Two questions were addressed: (i) Are any RSNs altered in aMCI? (ii) Do changes in functional connectivity relate to possible structural changes? Independent component analysis of resting-state fMRI data identified eight spatially consistent RSNs. Only selected areas of the DMN and the executive attention network demonstrated reduced network-related activity in the patient group. Voxel-based morphometry revealed atrophy in both medial temporal lobes (MTL) of the patients. The functional connectivity between both hippocampi in the MTLs and the posterior cingulate of the DMN was present in healthy controls but absent in patients. We conclude that in individuals at risk for AD, a specific subset of RSNs is altered, likely representing effects of ongoing early neurodegeneration. We interpret our finding as a proof of principle, demonstrating that functional brain disorders can be characterized by functional-disconnectivity profiles of RSNs.

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Crossref · 10.1073/pnas.0708803104

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  • The default mode network shows reduced connectivity in early-stage Alzheimer's disease.

    “a functional network showing reduced connectivity in early-stage Alzheimer’s disease (Sorg et al., 2007; Chhatwal et al., 2013)”

    From White matter diffusion alterations precede symptom onset in autosomal dominant Alzheimer’s disease (2018) · cites this paper as Sorg et al., 2007

    The Abstract says the default mode network has reduced functional connectivity in AD, and the Results report diminished connectivity in patients with amnestic mild cognitive impairment. The study’s patients were at high risk for AD, however, rather than diagnosed with early-stage AD; its direct finding does not establish the claim for that population. (LLM, conf=0.84)

    Experimental — accuracy not yet measured
  • The dynamics of functional connectivity alteration, both spatial and temporal, differ from patterns observed in Alzheimer's disease patients.

    “The dynamics of alteration, both spatial and temporal, differ from patterns observed in AD patients, which is marked with early altered FC in the default mode network and aggravated FC in the transition from mild cognitive impairments to AD (Greicius et al., 2004;Rombouts et al., 2005;Sorg et al., 2007;Sheline et al., 2010a,b).”

    From Early Alterations in Functional Connectivity and White Matter Structure in a Transgenic Mouse Model of Cerebral Amyloidosis (2014) · cites this paper as Sorg et al., 2007

    The Abstract and Results report reduced default-mode-network functional connectivity in people with amnestic MCI, supporting the claim of early alteration. The study compares these patients with healthy controls, not with AD patients over time; the Results say a two-year follow-up was still underway. It therefore does not establish distinct spatial and temporal dynamics or worsening connectivity during the transition from MCI to AD. Page numbers are unavailable in our copy. (LLM, conf=0.85)

    Experimental — accuracy not yet measured
  • Default mode network connectivity was reported affected in subjects at risk of developing Alzheimer's disease, including patients with mild cognitive impairment, cognitively healthy elders with amyloid deposits, and midlife carriers of the APOE4 risk allele.

    “Additionally, DMN connectivity was reported affected in subjects at risk of developing AD including patients with mild cognitive impairment (Rombouts et al., 2005;Sorg et al., 2007), in cognitively healthy elders with amyloid deposits (Hedden et al., 2009;Sperling et al., 2009;Sheline et al., 2010b), and in midlife carriers of APO ␧4 risk allele (Sheline et al., 2010a;Canuet et al., 2012).”

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Authors
Sorg, C., Riedl, V., Mühlau, M., Calhoun, V. D., Eichele, T., Läer, L., Drzezga, A., Förstl, H., Kurz, A., Zimmer, C., & Wohlschläger, A. M.
Affiliations
  • Departments of *Psychiatry,
  • Munich Center for Neurosciences – Brain and Mind (DE)
  • Neurology,
  • University of New Mexico (US)
  • University of Bergen (NO)
  • Technical University of Munich (DE)
  • TUM Klinikum (DE)
Venue
Proceedings of the National Academy of Sciences
Published
2007-11-20
Volume
104
Issue
47
Pages
18760-18765
ISSN
  • 0027-8424 (ISSN-L)
  • 1091-6490
OpenAlex
W2007572953
Cited by
1,036
References
58
Citations by year
2026: 22 · 2025: 30 · 2024: 20 · 2023: 34 · 2022: 35 · 2021: 57 · 2020: 46 · 2019: 69 · 2018: 56 · 2017: 61 · 2016: 65 · 2015: 63 · 2014: 86 · 2013: 85 · 2012: 100
FWCI
20.48
Type
journal article
Language
en
Open access
Locations
  • Proceedings of the National Academy of Sciences (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • mediaTUM (Technical University of Munich) (submittedVersion)
Topics
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Functional Brain Connectivity Studies
  • Health Sciences › Medicine › Psychiatry and Mental health › Dementia and Cognitive Impairment Research
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Advanced MRI Techniques and Applications
Keywords
Alzheimer's disease, resting-state networks, amnestic mild cognitive impairment, default mode network, functional connectivity, structural connectivity, medial temporal lobe atrophy, hippocampal connectivity, posterior cingulate cortex, early neurodegeneration
MeSH terms
Aged, Aged, 80 and over, Alzheimer Disease, Cognition Disorders, Female, Health, Hippocampus, Humans, Magnetic Resonance Imaging, Male, Middle Aged, Nerve Net, Risk Factors

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