Poster Session 06 Program Schedule
02/15/2024
04:00 pm - 05:15 pm
Room: Majestic Complex (Posters 61-120)
Poster Session 06: Aging | MCI | Neurodegenerative Disease - PART 2
Final Abstract #110
Investigating Neural Associations of Apathy in Alzheimer’s and Parkinson’s Disease Using Track-Weighted Dynamic Functional Connectivity
Julianne Yoon, University of Michigan at Ann Arbor, Ann Arbor, United States
Bryan Chen, Department of Neurology, Columbia University Irving Medical Center, New York, United States
Nora Vanegas, Department of Neurology, Baylor College of Medicine, Houston, United States
Yunglin Gazes, Department of Neurology, Columbia University Irving Medical Center, New York, United States
Category: Neuroimaging
Keyword 1: apathy
Keyword 2: dementia - Alzheimer's disease
Keyword 3: Parkinson's disease
Objective:
Apathy is one of the most common neuropsychiatric symptoms in Alzheimer’s (AD) and Parkinson’s disease (PD). Characterized as the reduction in motivation and goal-directed behavior, the symptom contributes to functional decline, leading to increased caregiver stress and heightened costs of care. While previous neuroimaging studies provide a foundation for the neural basis of apathy, their studies lack a dimensional measure of apathy and use unimodal imaging methods to measure these associations.
Our research aimed to address these gaps by combining diffusion MRI (dMRI) to assess structural connectivity and resting-state functional MRI (fMRI) to assess functional connectivity. This novel approach enabled the integration of structural connectivity with functional activation patterns across time. We hypothesized that frontosubcortical white matter tracts would display negative associations between connectivity and apathy in AD and PD patients.
Participants and Methods:
The current study included 18 AD participants and 21 PD participants, where five participants with amnestic mild cognitive impairments (aMCI) and one participant with mild cognitive impairment (MCI) were analyzed as AD participants due to small sample size. Apathy was assessed in these subjects through the Dimensional Apathy Scale (DAS), a caregiver-reported measure encompassing three dimensions: executive, emotional, and behavioral/cognitive initiation. These subscale scores were totaled and analyzed as a composite score of apathy.
Track-weighted dynamic functional connectivity (TW-dFC) was employed to combine dMRI tractography and resting-state functional connectivity to generate 4D track-weighted images representing mean functional connectivity across all connected nodes at each white matter voxel over time for each subject. Independent component analysis (ICA) was performed with FSL’s MELODIC tool to identify distinct patterns of connectivity, the expressions of which were tested for differences between AD and PD, and for associations with DAS.
Results:
The results showed that expressions of two connectivity patterns were greater in the AD than the PD group (pattern 1: z = 2.34, p < 0.00977; pattern 2: z = 1.65, p < 0.04950), and greater expression of these patterns were associated with lower total DAS only in the AD group (pattern 1: z = -2.12, p < 0.01680). Pattern 1 consists of the genu of the corpus callosum and the right anterior thalamic radiation, and Pattern 2 consists of the forceps minor. These findings suggest that differential connectivity patterns underlie apathy in AD and PD, which may be explained by disease-specific neurodegeneration, which could be better supported through future analyses involving a greater sample size and comparisons with a control group. These findings may be useful in understanding the development of apathetic symptoms in these patient populations.
Conclusions:
Our exploratory study using TW-dFC highlights the potential for this tool in comprehending the structural and functional connectivity underlying non-motor symptoms in AD and PD. Future research may also explore subscale-specific apathy scores to enrich the understanding of connectivity, especially across dementias. Overall, this method demonstrates a capability to further understanding of the communication and organization of the brain in the context of neurodegenerative diseases.
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