White matter matters in Parkinson’s disease

Two studies presented at EAN 2020 demonstrated that longitudinal changes of microstructural white matter (WM) damage are associated with both motor and global cognitive deterioration in Parkinson’s disease (PD) [1,2].

In the first study, disruption of WM tracts and cognitive decline was found after deep brain stimulation of the subthalamic nucleus (STN-DBS). The trajectories of electrodes in STN-DBS intersected with tracts involved in different cognitive domains [1].

A group of 51 consecutive PD patients underwent neuropsychological assessment before DBS and 6 months after in on-drug/on-stimulation condition. There was a decline in global cognitive evaluation and in selective cognitive domains including episodic verbal memory, executive functions, and phonemic and semantic verbal fluency. Decline in cued recall in verbal memory correlated with the proportion of lesions of the superior longitudinal fasciculus.

The second study showed that longitudinal evolution of macro- and microstructural damage follows different pathways in PD. Most of all, macroscopic damage, in vivo assessed by structural MRI, might provide a sensitive biomarker of disease progression in PD [2].

The 154 participating PD patients received clinical assessment, cognitive evaluation, and an MRI scan once a year over a period of 48 months. At baseline, diffusion tensor imaging (DTI) metrics differed significantly between total and normal appearing WM (NAWM) (P≤0.001). During follow-up, Unified Parkinson Disease Rating Scale (UPDRS)-III score and WM lesion volume (both P<0.001) significantly progressed. Longitudinal differences of mean, axial, and radial diffusivity values significantly correlated with UPDRS-III and Addenbrooke Cognitive Examination total score. Regression analyses showed a significant interaction between axial diffusivity and Mini-Mental State Examination (MMSE) and UPDRS-III score, both in total WM and in NAWM.

The authors concluded that, even though not evident macroscopically, NAWM appeared to be damaged. Microstructural damage at baseline was associated with cognitive and motor status. No such association was found for longitudinal evolution of NAWM microstructural damage.

1. Costentin G, et al. Abstract O1022, EAN 2020.
2. Scamarcia PG, et al. Abstract O3010, EAN 2020.

 



Posted on 9 September 202017 May 2024