Imagine you have a favorite running path that you’ve been using for years. You start off with smooth pavement, but over time you notice cracks and bumps appearing. That’s kind of what happens to the deep gray nuclear structures in the brains of people with Parkinson’s disease (PD). A long-term study recently investigated these changes by taking brain images using a technique called diffusion tensor imaging (DTI) for 12 years. This study, which included 72 PD patients and 77 controls, found that certain DTI metrics changed over time and were associated with the progression of PD symptoms. For example, one metric called mean diffusivity (MD) increased over time in the putamen and globus pallidus, two deep brain structures involved in movement control. Another metric called fractional anisotropy (FA) increased in the thalamus at year six and decreased in the putamen and globus pallidus at year 12. Additionally, MD in the caudate nucleus correlated with disease duration and motor scores. These findings suggest that DTI can be a valuable tool for tracking PD progression and potentially identifying new ways to intervene in the disease process. If you’re interested in learning more about this fascinating research, check out the full article!

BackgroundDeep gray nuclear pathology relates to motor deterioration in idiopathic Parkinson’s disease (PD). Inconsistent deep nuclear diffusion tensor imaging (DTI) findings in cross-sectional or short-term longitudinal studies have been reported. Long-term studies in PD are clinically challenging; decade-long deep nuclear DTI data are nonexistent. We investigated serial DTI changes and clinical utility in a case-control PD cohort of 149 subjects (72 patients/77 controls) over 12 years.MethodsParticipating subjects underwent brain MRI at 1.5T; DTI metrics from segmented masks of caudate, putamen, globus pallidus and thalamus were extracted from three timepoints with 6-year gaps. Patients underwent clinical assessment, including Unified Parkinson Disease Rating Scale Part 3 (UPDRS-III) and Hoehn and Yahr (H&Y) staging. A multivariate linear mixed-effects regression model with adjustments for age and gender was used to assess between-group differences in DTI metrics at each timepoint. Partial Pearson correlation analysis was used to correlate clinical motor scores with DTI metrics over time.ResultsMD progressively increased over time and was higher in the putamen (p < 0.001) and globus pallidus (p = 0.002). FA increased (p < 0.05) in the thalamus at year six, and decreased in the putamen and globus pallidus at year 12. Putaminal (p = 0.0210), pallidal (p = 0.0066) and caudate MD (p < 0.0001) correlated with disease duration. Caudate MD (p < 0.05) also correlated with UPDRS-III and H&Y scores.ConclusionPallido-putaminal MD showed differential neurodegeneration in PD over 12 years on longitudinal DTI; putaminal and thalamic FA changes were complex. Caudate MD could serve as a surrogate marker to track late PD progression.

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