Distinct Patterns of Rich Club Organization in Alzheimer’s Disease and Subcortical Vascular Dementia: A White Matter Network Study

Article type: Research Article

Authors: Lee, Wha Jin^{a; 1} | Han, Cheol E.^{b; 1} | Aganj, Iman^c | Seo, Sang Won^{d; *} | Seong, Joon-Kyung^{a; *}

Affiliations: [a] School of Biomedical Engineering, Korea University, Seoul, Republic of Korea | [b] Department of Electronics and Information Engineering, Korea University, Sejong, Republic of Korea | [c] Department of Radiology, Harvard Medical School, Boston, Massachusetts, United States of America | [d] Department of Neurology, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul, Republic of Korea

Correspondence: [*] Correspondence to: Joon-Kyung Seong, PhD, School of Biomedical Engineering, Korea University, Seoul, Republic of Korea. Tel.: +82 2 3290 5660; Fax: +82 2 921 6434; E-mail: jkseong@korea.ac.kr and Sang Won Seo, MD, PhD, Department of Neurology, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul, Republic of Korea, 50 Irwon-dong, Gangnam-gu, Seoul 135-710, Republic of Korea. Tel.: +82 2 3410 1233; Fax: +82 2 3410 0052; E-mail: sangwonseo@empal.com.

Note: [1] These authors contributed equally to this work.

Abstract: Recent advances in neuroimaging technology have shown that rich club organization in human brain networks plays a crucial role in global communication and cognitive functionality. In this study, we investigated rich club organization within white matter structural brain networks in two common types of dementia, Alzheimer’s disease (AD) and subcortical vascular dementia (SVaD). We recruited 30 AD patients ([11C] Pittsburgh compound-B (PiB) PET positive), 39 SVaD patients (PiB negative), and 72 age-, gender-, and education-matched cognitively normal (CN) subjects. Rich club organization was significantly disrupted in both dementia patient groups, which exhibited higher rich club coefficients than the CN group. Rich club organization in the patient groups was primarily disrupted over the left frontal and left middle temporal areas when compared to the CN group. The number of rich club nodes was significantly reduced in the dementia groups, which was more severe in SVaD (p = 0.0107, permutation-based t-test). Although rich club organization was disrupted both in the patient groups, its disruption pattern is different between them. The rich-club connections normalized by degree-and-strength preserved random networks were significantly increased in the dementia groups with SVaD more severely, and feeder connections were reduced more significantly than in AD. Furthermore, SVaD patients exhibited more sporadic disruption in white matter connectivity than AD patients, with local connections showing a more significant degree of deterioration. Combined with the distinct disruption in rich club nodes, these findings may imply a differing role for rich club organization in AD and SVaD, due to different pathological mechanisms.

Keywords: Alzheimer’s disease, diffusion tensor imaging, diffusion tractography, subcortical vascular dementia

DOI: 10.3233/JAD-180027

Journal: Journal of Alzheimer's Disease, vol. 63, no. 3, pp. 977-987, 2018