Alzheimer Hastalığında Olağan Durum Ağı Bağlantısallığı

2019; 30(4): 279-286
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Default Mode Network Connectivity in Alzheimer’s Disease

Objective: Alzheimer’s Disease (AD) is a neurodegenerative condition
characterized by functional and structural changes in the brain that are
increasingly better visualized with the advances in new brain imaging
techniques. Connectivity changes under the resting state condition
especially in the internal connectivity network, named as the default
mode network (DMN), are observed in AD. This paper aimed to
investigate and discuss the findings on DMN connectivity.
Method: The studies carried out by functional magnetic resonance
imaging (fMRI), using the two most widely applied techniques, the
seed-based method and independent component analysis (ICA), have
been investigated.
Results: Studies generally indicate a progressive impairment in DMN
connectivity during the course of AD. It has been also stated that DMN
subsystems show differential connectivity patterns in the preclinical
and prodromal stages of AD. There is also evidence suggesting that
impairment in DMN connectivity could be associated with different
connectivity patterns in other networks. Furthermore, findings point
towards a relationship between DMN and AD-related neuropathology
and genetic risk factors.
Conclusion: It may be proposed that AD is a generalized disconnection
syndrome that causes functional impairments in resting state networks,
particularly in DMN. In addition to this, AD-related functional
connectivity changes observed in preclinical cases and risk carriers
might be a potential bio-marker for AD.
Key Words: Alzheimer’s disease, magnetic resonance imaging, functional neuroimaging