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White matter myelin profiles linked to clinical subtypes of Parkinson's disease
Tobias R Baumeister1, Jowon L Kim2, Maria Zhu3
1School of Biomedical Engineering, University of British Columbia, Vancouver, Canada.
Background:
White matter (WM) microstructural integrity is important for effective brain functioning and alterations have been shown in many neurodegenerative diseases.
Purpose:
To investigate WM myelin profiles and their relation to clinical features of Parkinson's disease (PD).
Study Type:
Retrospective cross-sectional.
Population:
In all, 29 PD subjects and 15 healthy controls.
Field Strength/Sequence:
Multiecho GRASE with 10 msec echo spacing and echo planar imaging (EPI) diffusion-weighted (b-value = 700 with 32 gradient directions) on a 3T scanner.
Assessment:
Myelin water fraction (MWF) and fractional anisotropy (FA) across 20 WM regions of interest (ROIs) were compared between groups. Partial least squares (PLS) was used to associate MWF and FA with clinical and behavioral measures.
Statistical Tests:
Group comparisons were done using two-sample t-tests. PLS was assessed with permutation tests. Bootstrapping was used to investigate the robustness of imaging features.
Results:
No group differences in myelin content could be detected with univariate tests. A three-component PLS model linked MWF profiles to clinical phenotypes but no FA profiles. The three components appeared to follow along broad motor/nonmotor subtypes of "akinetic-rigid," "tremor-predominant," and "depression/apathy" subtypes, respectively. The first component showed associations between overall motor scores (r = -0.43, P = 0.0196) and cognitive performance (r = 0.44, P = 0.0171) with interhemispheric and long-range association fibers. A second component linked overall motor scores (r = -0.58, P = 0.0009) and tremor scores (r = -0.48, P = 0.0091) to predominantly projection fibers. The last component related depression (r = -0.60, P = 0.0006) and apathy scores (r = -0.66, P = 0.0001 and r = -49, P = 0.0072) to a mixture of association and projection fibers.
Data Conclusion:
MWF was robustly linked to distinct clinical subtypes of PD and may serve as an additional tool to characterize the disease.
Level Of Evidence:
4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;50:164-174.
Insights
Myelin water fraction (MWF) effectively characterizes Parkinson's disease (PD) subtypes, linking white matter integrity to clinical features. This imaging biomarker may aid in disease characterization.
Area of Science:
- Neuroimaging
- Neuroscience
- Biomarkers
Background:
- White matter (WM) microstructural integrity is crucial for brain function.
- Alterations in WM are observed in neurodegenerative diseases like Parkinson's disease (PD).
Purpose of the Study:
- To investigate white matter myelin profiles in PD.
- To determine the relationship between myelin profiles and clinical features of PD.
Main Methods:
- Retrospective cross-sectional study with 29 PD subjects and 15 healthy controls.
- Utilized multiecho GRASE imaging on a 3T scanner to assess myelin water fraction (MWF) and fractional anisotropy (FA).
- Employed partial least squares (PLS) to correlate MWF and FA with clinical and behavioral measures.
Main Results:
- Univariate tests showed no significant group differences in myelin content.
- A three-component PLS model revealed significant links between MWF profiles and distinct PD clinical phenotypes (motor and non-motor).
- Specific components correlated with akinetic-rigid, tremor-predominant, and depression/apathy subtypes, demonstrating associations with motor scores, cognitive performance, and mood.
Conclusions:
- Myelin water fraction (MWF) is robustly associated with distinct clinical subtypes of Parkinson's disease.
- MWF shows potential as an additional tool for characterizing PD and its diverse clinical presentations.