24 Sep Amyloid and Cerebrovascular Disease Have Different Effects on Brain Networks

MedicalResearch.com Interview with:
Juan Helen Zhou, PhD, on behalf of the co-authors
Associate Professor and Principal Investigator
Neuroscience and Behavioural Disorders (NBD) Programme
Duke-NUS Medical School, Singapore 

MedicalResearch.com: What is the background for this study?

Response: Alzheimer’s disease and cerebrovascular disease are among the leading disorders affecting the elderly, with up to 50 per cent of dementia patients showing co-occurrence of both disorders. It is therefore of great interest to understand the influence of co-occurring Alzheimer’s disease and cerebrovascular disease pathologies on brain changes, and examine if such changes are able to track early differential disease progression. Past cross-sectional studies have suggested that Alzheimer’s disease and cerebrovascular disease pathologies contribute independently to brain functional and structural changes, and cognitive decline.

Our study sought to demonstrate the independent contributions of both pathologies to brain functional networks in a longitudinal cohort of mild cognitive impairment patients, often regarded as early stage of the disease.

MedicalResearch.com: What are the main findings?

Response: We showed that baseline amyloid-β burden, a hallmark of Alzheimer’s disease, was associated with longitudinal functional connectivity declines in the default mode network, a brain network associated with episodic and autobiographical memory.

On the other hand, baseline cerebrovascular disease burden was associated with longitudinal functional connectivity disruptions in the executive control network associated with executive functioning.

MedicalResearch.com: What should readers take away from your report?

Response: Our findings highlight that amyloid-β burden and cerebrovascular disease burden have differential influences on changes in brain functional networks over time in the pre-dementia stage, which reflect the underlying pathology and may be used to track early changes in Alzheimer’s disease and cerebrovascular disease.

MedicalResearch.com: What recommendations do you have for future research as a result of this work? 

Response: Given our findings of the divergent effects of Alzheimer’s disease and cerebrovascular disease on brain functional network changes, as well as the high co-occurrence of these two diseases in the elderly population, future studies need to take into consideration the effects of cerebrovascular disease when studying brain and cognitive changes in individuals across the Alzheimer’s disease spectrum.

On our end, we would like next to examine the additive and interactive effects of amyloid-β, tau (both are hallmarks of Alzheimer’s disease), and specific types of cerebrovascular lesions on functional and microstructural brain changes in individuals at the early stages of Alzheimer’s disease, even before the appearance of mild cognitive impairment. This will likely facilitate hunting of early disease epicentres and treatment search to prevent or slow down disease progression. 

MedicalResearch.com: Is there anything else you would like to add? 

Response: For this study, we studied 30 patients with amnestic mild cognitive impairment and 55 patients with subcortical vascular mild cognitive impairment recruited through the Samsung Medical Center in Seoul between September 2008 and September 2011. All patients had baseline Pittsburgh Compound B Positron Emission Tomography (PiB PET) scans and annual structural magnetic resonance imaging (MRI) and task-free functional magnetic resonance imaging (fMRI) scans for up to four years.

This work was done jointly by researchers from Duke-NUS Medical School, Singapore and Associate Professor Sang Won Seo and Dr. Hyemin Jang from Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul.

This study was funded by the governments of the Republic of Korea and Singapore. 

Citation:

Chong, J.S.X., Jang, H., Kim, H.J., et al. Amyloid and cerebrovascular burden divergently influence brain functional network changes over time. Neurology. 2019;93:1-12. doi: 10.1212/WNL.0000000000008315

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Last Updated on September 24, 2019 by Marie Benz MD FAAD