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Small-world networks and functional connectivity in Alzheimer's disease
Stam CJ, Jones BF, Nolte G, Breakspear M, Scheltens P.. Cerebral cortex (New York, N.Y. : 1991), 2006-02-01
Topic: Amyloid, tau and blood-test diagnosis
We investigated whether functional brain networks are abnormally organized in Alzheimer's disease (AD). To this end, graph theoretical analysis was applied to matrices of functional connectivity of beta band-filtered electroencephalography (EEG) channels, in 15 Alzheimer patients and 13 control subjects. Correlations between all pairwise combinations of EEG channels were determined with the synchronization likelihood. The resulting synchronization matrices were converted to graphs by applying a threshold, and cluster coefficients and path lengths were computed as a function of threshold or as a function of degree K. For a wide range of thresholds, the characteristic path length L was significantly longer in the Alzheimer patients, whereas the cluster coefficient C showed no significant changes. This pattern was still present when L and C were computed as a function of K. A longer path length with a relatively preserved cluster coefficient suggests a loss of complexity and a less optimal organization. The present study provides further support for the presence of "small-world" features in functional brain networks and demonstrates that AD is characterized by a loss of small-world network characteristics. Graph theoretical analysis may be a useful approach to study the complexity of patterns of interrelations between EEG channels.
Key findings
- For a wide range of thresholds, the characteristic path length L was significantly longer in the Alzheimer patients, whereas the cluster coefficient C showed no significant changes.
Why it matters
In 15 Alzheimer patients and 13 controls, this EEG study found a longer characteristic path length in the Alzheimer patients while the cluster coefficient showed no significant change, suggesting a loss of small-world network organization. It is a small study of brain network patterns and provides no information on treating, curing or preventing Alzheimer's disease.
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Study details
- Evidence strengthLow
How this study scored 55/100
Published in a peer-reviewed journal. Scored zero for study design, sample size, effect reported, studied in people and randomised / blinded because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Cerebral cortex (New York, N.Y. : 1991)) |
| Journal's citation record | 3 / 4 | Cerebral Cortex: journal h-index 345 (OpenAlex, 2026-10-29) |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 1 / 5 | 2007 — within 20 year(s) of the newest study here |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | 7 / 7 | Cited 1,285 times (OpenAlex, 2026-10-10) |
| Citations per year | 5 / 5 | 61.2 citations a year over 21 year(s) since 2007 |
| Impact for its field and year | 4 / 6 | Cited 18.6× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 3 / 6 | Cited by 17 other studies in this library |
| Still being cited | 3 / 4 | Cited 103 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 4 / 4 | Last-listed author Philip Scheltens: h-index 181 (OpenAlex, whole career) |
| Institution's track record | 3 / 3 | National Institutes of Health: institution h-index 2,723 (OpenAlex) |
| Multi-centre collaboration | 2 / 3 | OpenAlex lists 6 institution(s) in 4 countries |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 16452642) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Total | 55 / 100 | — |
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Read the original
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Cite this study APA, Vancouver, BibTeX · download .bib or .ris
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APA 7th
Stam, C. J., Jones, B. F., Nolte, G., Breakspear, M., & Scheltens, P. (2007). Small-world networks and functional connectivity in Alzheimer's disease. Cerebral cortex (New York, N.Y. : 1991). https://doi.org/10.1093/cercor/bhj127
Vancouver
Stam CJ, Jones BF, Nolte G, Breakspear M, Scheltens P. Small-world networks and functional connectivity in Alzheimer's disease. Cerebral cortex (New York, N.Y. : 1991). 2007. doi:10.1093/cercor/bhj127. PMID: 16452642.
BibTeX
@article{stam2007-16452642,
author = {Stam, C. J. and Jones, B. F. and Nolte, G. and Breakspear, M. and Scheltens, P.},
title = {{Small-world networks and functional connectivity in Alzheimer's disease}},
journal = {Cerebral cortex (New York, N.Y. : 1991)},
year = {2007},
doi = {10.1093/cercor/bhj127},
pmid = {16452642},
url = {https://doi.org/10.1093/cercor/bhj127}
}
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