Different neurological disorders found to result from varying alterations in brain function
A team of scientist from Singapore and South Korea have discovered that patients with Alzheimer's disease or cerebrovascular disease display differences in early stage cognitive impairment.
The cross-sectional study was done previously on a Singaporean cohort and indicated that Alzheimer's disease and cerebrovascular disease have varying effects on neuron communication of differing brain networks.
The researchers hope that the differences in changes in brain function before disease manifestation can assist doctors in risk prediction or understanding the type of dementia a patient may have.
Based on the study the brain's functional networks have been identified to be altered differently when the patient has either Alzheimer's disease of Cerebrovascular disease.
Alzheimer's Disease: Reduced functional connectivity in the Default Mode Network (DMN), linked to memory function.
Cerebrovascular Disease: Disruptions in the Executive Control Network (ECN), linked to working memory, self-control, and cognitive flexibility.
There also have been no previous studies analyzing the links between identifiers of disease pathology and alterations in functional connectivity of brain networks.
"Alzheimer’s disease frequently co-occurs with cerebrovascular disease, especially in Asia, where mixed dementia cases account for up to 50 percent of dementia cases," explained Associate Professor Juan Helen Zhou, senior and corresponding author of the study, from the Neuroscience and Behavioural Disorders (NBD) Programme at Duke-NUS Medical School, Singapore. "Understanding the influence of co-occurring Alzheimer’s disease and cerebrovascular disease pathologies on brain functional connectivity networks may help doctors track early differential disease progression and predict future cognitive decline."
This study was conducted in collaboration with Duke-NUS Medical School, Singapore and researchers from Sungkyunkwan University School of Medicine and Ulsan University School of Medicine, located in Seoul. Participants were recruited from Samsung Medical Center, at Sungkyunkwan University School of Medicine, that included people who showed early signs of Alzheimer’s disease, and cerebrovascular disease.
Through positron emission tomography (PET) scans, participants were examined for the presence of amyloid-beta plaques in the brain which is associated with Alzheimer's disease. Structural MRI scans were also done to check for signs of cerebrovascular disease associated with vascular dementia. The scans were done every year up to four years.
The researcher found that there is a decrease in DMN for people with amyloid-beta plaques as time passed. There was also an increase in ECN interactions for participants with early stages of vascular dementia.
“More studies are needed with larger numbers of participants and longer follow-up periods, but these results suggest that these changes in brain network connections could potentially be used to track early changes in Alzheimer’s disease and cerebrovascular disease,” said Associate Professor Sang Won Seo, a senior and corresponding author of the study from Samsung Medical Center.
Looking ahead, the researchers hope to examine the additive and interactive effects of Alzheimer's disease biomarkers and specific types of cerebrovascular lesions in the brain. Comparing between participants who have normal and mildly impaired cognition to help in prognosis and treatment planning.
The research paper was published in September 2019 on Neurology.