Alzheimer's and Parkinson's cause similar cognitive symptoms, but show opposing patterns on MRI
Alzheimer’s and Parkinson’s Disease are similarly devastating neurological conditions, but they have contrasting alterations in brain connectivity.
A new comparative analysis in Academic Radiology describes multiple variations of altered brain connectivity linked to cognitive decline in both Alzheimer’s (AD) and Parkinson’s (PD). Despite causing similar cognitive dysfunction for some patients, functional MRI scans suggest the two conditions have opposing connectivity patterns in some regions of the brain.
“Both diseases exhibit widespread reductions in functional connectivity across networks, leading to their classification as disconnection syndromes,” Guoguang Fan, PhD, with the Department of Radiology at the first hospital of China Medical University, and colleagues explained. “There is a lack of detailed exploration into the specific patterns of whole-brain functional connectivity changes. Additionally, studies on inter-network functional connectivity between subnetworks are scarce.”
For the study, researchers conducted resting state functional MRI scans on three sets of people—one with AD and mild cognitive impairment (MCI), one with PD and MCI and a group of controls. Participants also underwent cognitive assessments, which the team compared in relation to connectivity patterns observed in different brain networks.
Eight functional networks were identified. Both MCI groups displayed similar variations in the precuneus—an area of the brain known to be associated with aspects of cognitive function—which the team suggested might play a “compensatory role” in both conditions.
In the AD group, researchers noted decreased internetwork functional connectivity mainly around the default mode network (DMN). Intra-connectivity in the DMN was especially reduced in this group, though it was significantly higher in the salience network (SN). In contrast, the opposite patterns in these networks were observed in the PD group.
“It can be intuitively found that the core changes of these two diseases are respectively DMN and SN, aligning partially with known pathological changes,” the authors noted. “This insight offered new ideas for early treatment and precision treatment. Among them, functional connectivity changes in DMN and SN may be the most sensitive indicators for early clinical diagnosis.”
The team indicated that this new information on the pathogenesis of both conditions could be useful for the development of interventions targeted at slowing cognitive decline.
Learn more about the findings here.
In addition to her background in journalism, Hannah also has patient-facing experience in clinical settings, having spent more than 12 years working as a registered rad tech. She began covering the medical imaging industry for Innovate Healthcare in 2021.