Altered white matter connection from the locus coeruleus to the thalamus in Parkinson's disease

Parkinson's disease (PD) is the fastest growing neurodegenerative movement disorder. It is characterized by both motor and non-motor, including neuropsychiatric disturbances such as depression and anxiety. The locus coeruleus (LC), a small nucleus in the brainstem, plays a key role in these symptoms and has white matter connections to the thalamus. This study aims to investigate this LC-thalamic tract in PD patients using ultra-high-field diffusion-weighted imaging (DWI) and to examine its relationship with non-motor symptoms.

100 participants, including 69 early-stage PD and 31 healthy control (HC) participants were evaluated using several questionnaires and a 7T diffusion MRI scan. Tractography was performed to reconstruct the LC-thalamic white matter tract, and diffusion parameters (FA, MD, AD, RD) were analysed.

PD patients showed significantly higher mean diffusivity (MD) and axial diffusivity (AD) in the white matter tissue compared to HC, indicating reduced white matter integrity.

This study shows the feasibility to visualize the LC-thalamic tract with the use of 7T DWI data. The results provide evidence of the association between the integrity of the white matter tracts and early PD development, highlighting its potential as a target for therapeutic interventions. Further research is needed to elucidate the role of the LC and its white matter connections in the progression of PD and neuropsychiatric and other symptoms.