Patients whose PET and MR images show beta-amyloid plaque accumulation in the brain experience a significantly faster path toward dementia than people with vascular dementia and no plaque deposits, according to a study published online September 11 in Neurology.
Researchers from South Korea found that the deterioration of default mode network connections in people with beta-amyloid plaque -- oftentimes a precursor to Alzheimer's disease -- decline on average 13.6 times faster annually than individuals with early stages of vascular dementia and no plaque buildup.
The findings bolster current information on how different physiological factors influence a person's particular form of dementia.
"These differences may reflect underlying changes in the brain that could be used to track early changes in people who are going to develop either Alzheimer's disease or dementia due to cerebrovascular disease," said study author Juan "Helen" Zhou, PhD, an associate professor in the neuroscience and behavioral disorders program at Duke-National University of Singapore Medical School, in a statement.
For this study, the researchers enrolled 30 people with mild cognitive impairment and memory problems and 55 people with mild cognitive impairment and damage to small blood vessels in the brain, an early indication of vascular dementia or dementia due to cerebrovascular disease.
Subjects initially underwent PET imaging to assess the degree of beta-amyloid plaques in the brain, followed by structural MRI scans to determine the extent of cerebrovascular disease, which is associated with vascular dementia. Functional MRI (fMRI) scans also were performed to measure how well brain regions -- particularly the default mode network, which is associated with working memory and performing tasks -- were connected and functioning properly. These scans were repeated every year for up to four years.
Zhou and colleagues observed a much steeper decline in default mode network interaction over the four years in subjects with beta-amyloid plaque accumulation than people with early signs of vascular dementia and no plaques in the brain. In fact, the rate of deterioration was on average 13.6 times faster on a yearly basis, which also confirmed a diagnosis of Alzheimer's disease.
"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," added study co-author Dr. Sang Won Seo, PhD, from the department of Samsung Medical Center in South Korea, in a statement.
The research was supported by the National Research Foundation of Korea, National Medical Research Council of Singapore, and Duke-National University of Singapore Medical School.
