Differential brain network changes in Alzheimer's patients with and without CeVD

September 20, 2017, Duke University

A new study of those with Alzheimer's disease (AD) with and without cerebrovascular disease (CeVD) has found that there are likely differential brain network changes suggesting differences in the underlying pathology for each of these seemingly similar brain disorders.

Given that dementia is one of the biggest public health and social care challenges facing the world today, this finding may greatly improve the ways in which doctors diagnose, treat, manage and anticipate the outcomes of treatments in patients with neurodegenerative disorders. Alzheimer's disease is the most common form of dementia accounting for up to 60% of all cases, while Alzheimer's with CeVD accounts for nearly 20% of all dementia cases in Asia . Alzheimer's disease frequently co-occurs with CeVD, which has emerged as the leading cause of age-related cognitive impairment especially in Asia.

The burden of dementia is increasing exponentially worldwide, especially in Asia-Pacific, with an estimation that dementia sufferers in the region will triple between now and 2050. It is projected that the region will have almost 71 million people with dementia by 2050. Similar to other parts of Asia, the prevalence of dementia in Singapore is also projected to rise rapidly, with projected patients of 53,000 in 2020 more than tripling to 187,000 by 2050 .

A new study by researchers at Duke-NUS Medical School (Duke-NUS) and the National University of Singapore Yong Loo Lin School of Medicine (NUS Medicine), on a local cohort of 235 Singapore residents with prodromal and clinical Alzheimer's disease showed differential functional connectivity and structural network changes in the brains of patients with and without CeVD.

The human brain is made up of many regions with different functions, all of which need to communicate with each other to execute specific tasks. This collaborative process within the brain is known as functional connectivity, which exists when persons are at rest or performing tasks. Using state-of-the-art functional and structural Magnetic Resonance Imaging (fMRI) methods, both low-level sensorimotor and high-level cognitive networks in the human brain such as the default mode and executive control networks can be mapped non-invasively in vivo.

With an innovative network-sensitive neuroimaging method, the researchers were able to observe divergent brain functional connectivity and structural differences of these two high-level cognitive networks in both prodromal and clinical stages of AD patients with and without CeVD.

Specifically, only Alzheimer's disease without CeVD patients exhibited reduced posterior default mode network functional connectivity. In contrast, patients with the double burden of Alzheimer's disease and CeVD showed much greater reduction of frontal executive control network . Importantly, patients at the prodromal stages exhibited similar patterns and such network changes relate to hippocampal atrophy (marker of neurodegeneration) and white matter hyperintensity (marker of CeVD).

These different presentations of brain dysfunction, as detected by neuroimaging, for Alzheimer's patients with and without CeVD, suggests that there may need to be different clinical approaches in treating patients who only have Alzheimer's disease, and those who either only have CeVD or have CeVD as well as Alzheimer's disease.

Stressing the relevance of this finding, Assistant Professor Juan Helen Zhou of Duke-NUS, who is the senior author of this study, said: "Given that growing prevalence of Alzheimer's disease and CeVD in Asia and particularly in Singapore, our findings could potentially provide basis for better patient management, disease monitoring and long term treatment planning for patients with both Alzheimer's disease, and those with or without CeVD. This is the first time that the study demonstrated neural network structural and functional changes differ in AD with CeVD and without it."

The study's co-author, Associate Professor Christopher Chen of NUS Medicine, added: "Although there is a growing awareness of Alzheimer's disease and CeVD, however, due to lack of well-defined criteria and treatment guidelines, Alzheimer's disease with CeVD is largely underdiagnosed. With this study, we demonstrated the combined effects of Alzheimer's disease and CeVD on brain degeneration, and further studies could shed more light into the clinical characteristics of these two important pathologies."

Explore further: Alzheimer's disease biomarker identified across test sites

More information: Joanna Su Xian Chong et al, Influence of cerebrovascular disease on brain networks in prodromal and clinical Alzheimer's disease, Brain (2017). DOI: 10.1093/brain/awx224

Related Stories

Alzheimer's disease biomarker identified across test sites

September 12, 2017
A new study has demonstrated the potential to use a frequency distribution-based index of brain functional connectivity as a biomarker for detecting Alzheimer's disease and mild cognitive impairment (MCI). These new findings, ...

Alzheimer's disease patients with psychosis more likely to be misdiagnosed, study suggests

June 30, 2017
People with Alzheimer's disease who experience psychosis—including delusions and hallucinations—are five times more likely to be misdiagnosed with dementia with Lewy bodies compared to patients who do not, new research ...

Brain network decay detected in early Alzheimer's

August 19, 2013
In patients with early Alzheimer's disease, disruptions in brain networks emerge about the same time as chemical markers of the disease appear in the spinal fluid, researchers at Washington University School of Medicine in ...

What goes wrong in a brain affected by Alzheimer's disease?

August 22, 2013
The ability of different regions of the brain to communicate gradually breaks down with aging and in Alzheimer's disease, but there are key differences between these two processes. Some of these differences are reported in ...

Brain connectivity altered in type 2 diabetes

August 1, 2012
(HealthDay) -- Patients with type 2 diabetes mellitus (T2DM) have reduced functional connectivity in the default mode network, which is associated with insulin resistance in some brain regions, according to a study published ...

A spherical brain mapping of MR images for the detection of Alzheimer's disease

May 20, 2016
Diagnosis, treatment and care of dementia is one of the major concerns in neurology research and associated healthcare programs. Dementia affects older age groups with a greater frequency, and as our population ages, the ...

Recommended for you

Hypothesis underpinning dementia research 'flawed'

October 16, 2018
A hypothesis which has been the standard way of explaining how the body develops Alzheimer's Disease for almost 30 years is flawed, according to a University of Manchester biologist.

Study suggests biological basis for depression, anxiety, sleep disturbances in older adults

October 15, 2018
UC San Francisco researchers, in collaboration with the unique Brazilian Biobank for Aging Studies (BBAS) at the University of São Paulo, have shown that the earliest stages of the brain degeneration associated with Alzheimer's ...

Many cases of dementia may arise from non-inherited DNA 'spelling mistakes'

October 15, 2018
Only a small proportion of cases of dementia are thought to be inherited—the cause of the vast majority is unknown. Now, in a study published today in the journal Nature Communications, a team of scientists led by researchers ...

Scientists create new map of brain region linked to Alzheimer's disease

October 8, 2018
Curing some of the most vexing diseases first requires navigating the world's most complex structure—the human brain. So, USC scientists have created the most detailed atlas yet of the brain's memory bank.

Previously unknown genetic aberrations found to be associated with Alzheimer's progression

October 8, 2018
In a large-scale analysis of RNA from postmortem human brain tissue, researchers at the Icahn School of Medicine at Mount Sinai and Columbia University have identified specific RNA splicing events associated with Alzheimer's ...

Periodontal disease bacteria may kick-start Alzheimer's

October 4, 2018
Long-term exposure to periodontal disease bacteria causes inflammation and degeneration of brain neurons in mice that is similar to the effects of Alzheimer's disease in humans, according to a new study from researchers at ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.