Lifespan Trajectories of Fornix Volume and Tractography: A 5.0 T MRI Study
Poster No:
1004
Submission Type:
Abstract Submission
Authors:
Lei Gao1, Xiao Yu1
Institutions:
1Wuhan University, Wuhan, Hubei
First Author:
Co-Author:
Introduction:
Memory formation and maintenance rely on the fornix, whose role has been clarified through diffusion MRI. Fornix integrity and fiber length predict cognitive decline earlier than hippocampal changes. However, the lifespan trajectories of fornix volume and its relation to memory remain unclear. This study explores the evolution of fornix volume and tracts over the lifespan and their correlation with memory using 5.0T MRI. We hypothesize similar aging patterns for fornix volume and tracts, with tracts more vulnerable and a stronger predictor of memory.
Methods:
Study Sample
262 healthy adults aged 18 to 85 were included. Participants were free of DSM-5 axis 1 disorders, 95% right-handed. Exclusion criteria included neurological disorders, brain trauma, obesity (BMI >30), and severe cognitive impairment. The study was approved by Zhongnan Hospital's ethics committee, and informed consent was obtained from all participants.
Neurobehavioral Data
Cognitive tests included the MMSE, MoCA, DST, and Rey Auditory Verbal Learning Test.
MRI Data
Imaging was performed on a 5.0T MRI scanner (uMR Jupiter, UIH, China), including T1-weighted imaging (0.7 mm3) and multi-shell DTI (1.05 mm slice thickness, b values = 0, 1020, and 2025 s/mm2 in 32 directions). Real-time head motion monitoring ensured quality control.
Segmentation and Volumetric Analysis
The fornix was manually segmented, and T1 images were automatically segmented with FreeSurfer (version 7.4.1), validated visually. Total intracranial volume (TIV) was calculated.
Fornix Tractography
Tractography used automatic tracking with a fornix template in DSI Studio, semi-automatic tracking in TrackVis, and manual seeding with ROI at the fornix entry (4-10 mm diameter). Streamlines longer than 80 mm were excluded. Tract counts were normalized by total brain streamlines.
Lifespan Trajectories
Lifespan trajectories of fornix volume and tracts were analyzed using LOWESS, highlighting age-related changes.
Coupling Between Fornix Volume and Tracts
Spearman correlations assessed the relationship between fornix volume and tracts across the entire age range and in specific age groups.
Mediation and Moderation Analyses
Mediation and moderation analyses (SPSS macro-PROCESS, Hayes, 2018) explored the role of fornix integrity in age-related cognitive decline. Bootstrapping (10,000 samples) was used to assess indirect effects, controlling for gender, education, and TIV.
262 healthy adults aged 18 to 85 were included. Participants were free of DSM-5 axis 1 disorders, 95% right-handed. Exclusion criteria included neurological disorders, brain trauma, obesity (BMI >30), and severe cognitive impairment. The study was approved by Zhongnan Hospital's ethics committee, and informed consent was obtained from all participants.
Neurobehavioral Data
Cognitive tests included the MMSE, MoCA, DST, and Rey Auditory Verbal Learning Test.
MRI Data
Imaging was performed on a 5.0T MRI scanner (uMR Jupiter, UIH, China), including T1-weighted imaging (0.7 mm3) and multi-shell DTI (1.05 mm slice thickness, b values = 0, 1020, and 2025 s/mm2 in 32 directions). Real-time head motion monitoring ensured quality control.
Segmentation and Volumetric Analysis
The fornix was manually segmented, and T1 images were automatically segmented with FreeSurfer (version 7.4.1), validated visually. Total intracranial volume (TIV) was calculated.
Fornix Tractography
Tractography used automatic tracking with a fornix template in DSI Studio, semi-automatic tracking in TrackVis, and manual seeding with ROI at the fornix entry (4-10 mm diameter). Streamlines longer than 80 mm were excluded. Tract counts were normalized by total brain streamlines.
Lifespan Trajectories
Lifespan trajectories of fornix volume and tracts were analyzed using LOWESS, highlighting age-related changes.
Coupling Between Fornix Volume and Tracts
Spearman correlations assessed the relationship between fornix volume and tracts across the entire age range and in specific age groups.
Mediation and Moderation Analyses
Mediation and moderation analyses (SPSS macro-PROCESS, Hayes, 2018) explored the role of fornix integrity in age-related cognitive decline. Bootstrapping (10,000 samples) was used to assess indirect effects, controlling for gender, education, and TIV.
Results:
Bilateral fornix volumes decrease non-linearly with age, starting significantly after age 50, with declines of 4.43%, 10.97%, 19.81%, and 35.99% for the left fornix, and 3.03%, 8.97%, 16.17%, and 32.05% for the right fornix each decade. The decline rate nearly doubles after 50. In early adulthood, there was a leftward asymmetry, which shifted to rightward after age 60.
Fornix fiber tracts increase from age 18, peak in the early 40s, and decline sharply after. Early adulthood showed hemispheric asymmetry, with more tracts on the left. This difference decreased with age. Fiber tract reduction after 50 was 34.46%, 51.21%, and 61.14% for the left fornix, and 25.58%, 42.70%, and 23.76% for the right fornix.
Coupling between fornix volume and tractography increased with age, reflecting similar trajectories.
In the mediation model, fornix measures did not mediate the relationship between age and cognitive tests. In contrast, in the moderation model, fornix volume and fiber count moderated the relationship between age and cognitive tests, including the MMSE. These effects remained significant after controlling for gender, education, and TIV, suggesting the fornix influences the age-cognition relationship.
Fornix fiber tracts increase from age 18, peak in the early 40s, and decline sharply after. Early adulthood showed hemispheric asymmetry, with more tracts on the left. This difference decreased with age. Fiber tract reduction after 50 was 34.46%, 51.21%, and 61.14% for the left fornix, and 25.58%, 42.70%, and 23.76% for the right fornix.
Coupling between fornix volume and tractography increased with age, reflecting similar trajectories.
In the mediation model, fornix measures did not mediate the relationship between age and cognitive tests. In contrast, in the moderation model, fornix volume and fiber count moderated the relationship between age and cognitive tests, including the MMSE. These effects remained significant after controlling for gender, education, and TIV, suggesting the fornix influences the age-cognition relationship.
·From data preprocessing to lifespan trajectories to regression analysis results.
Conclusions:
The results highlight the lifespan changes in the neuroanatomy and white matter microstructure of the fornix and their links to cognitive functions.
Lifespan Development:
Aging
Lifespan Development Other 1
Neuroanatomy, Physiology, Metabolism and Neurotransmission:
White Matter Anatomy, Fiber Pathways and Connectivity 2
Novel Imaging Acquisition Methods:
Anatomical MRI
Multi-Modal Imaging
Keywords:
Aging
Cognition
Limbic Systems
WHITE MATTER IMAGING - DTI, HARDI, DSI, ETC
1|2Indicates the priority used for review
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