Although we know that mild cognitive impairment is a transitional stage between normal aging and Alzheimer's disease, changes in brain networks during this transformation have yet to be studied.
Dr. Jie Xiang and colleagues from Taiyuan University of Technology, China constructed brain networks using resting-state functional MRI data that were extracted from four populations (normal controls, patients with early mild cognitive impairment, patients with late mild cognitive impairment, and patients with Alzheimer's disease) using the Alzheimer's Disease Neuroimaging Initiative data set.
The researchers analyzed the characteristics of resting-state functional neural networks, and to observe mild cognitive impairment at different stages before the transformation to Alzheimer's disease.
Results showed that as cognitive deficits increased across the four groups, the shortest path in the resting-state functional network gradually increased, while clustering coefficients gradually decreased. This evidence indicates that dementia is associated with a decline of brain network efficiency. In addition, the changes in functional networks revealed the progressive deterioration of network function across brain regions from healthy elderly adults to those with mild cognitive impairment and Alzheimer's disease.
The alterations of node attributes in brain regions may reflect the cognitive functions in brain regions, and we speculate that early impairments in memory, hearing, and language function can eventually lead to diffuse brain injury and other cognitive impairments.
This study was published in Neural Regeneration Research (Vol. 8, No. 30, 2013).