Objective: This study aimed to investigate the differences in perivascular water diffusivity and structural neurofluid markers using diffusion tensor image-analysis along the perivascular space (DTI-ALPS), perivascular space (PVS) burden, and choroid plexus volume (CPV) in Parkinson’s disease (PD) and type 2 diabetes mellitus (T2DM).

Background: Alterations in perivascular fluid dynamics has been implicated in PD and metabolic disorders such as T2DM. However, the relative contributions of neurodegenerative and metabolic conditions to functional perivascular water diffusivity versus structural neurofluid markers remains to be elucidated.

Method: In this retrospective study, consecutive patients diagnosed with de novo idiopathic PD and disease control subjects who underwent 3T brain MRI between May 2017 and May 2023 were included. Subjects were classiifed into four groups according to PD and T2DM status and matched for age and sex. Perivascular water diffusivity was assessed using ALPS-index, and PVS burden and CPV were quantified on three-dimensional T1-weighted images and normalized to intracranial volume. Group differences were evaluated using analysis of variance with post hoc testing.

Results: A total of 132 subjects were included. The ALPS-index differed significantly among the four groups (P < 0.001), with both PD groups demonstrating significantly lower values than control groups, regardless of T2DM status: controls without T2DM (1.52 ± 0.10), controls with T2DM (1.49 ± 0.12), PD without T2DM (1.35 ± 0.11), and PD with T2DM (1.33 ± 0.10). No significant differences in the ALPS-index were observed between subjects with and without T2DM within the same diagnosis. Within the PD cohort, longer disease duration and older age were independently associated with lower ALPS-index values. CPV normalized to intracranial volume also differed significantly across group (P = 0.012) with higher values observed only in controls with T2DM, while PVS burden did not differ significantly.

Conclusion: In early-stage PD, impaired perivascular diffusivity was driven primarily by neurodegeneration, with no additive effect from T2DM. Conversely, choroid plexus remodeling reflected an interactive pattern where metabolic hypertrophy was attenuated in the presence of PD. These findings highlight a dissociation between functional fluid dynamics and structural neurofluid markers in the early disease stage.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/distinct-patterns-of-perivascular-diffusivity-and-choroid-plexus-volume-in-de-novo-parkinsons-disease-and-type-2-diabetes/