Diffusion tractography and functional connectivity profiles of the dorsal raphe nucleus in Parkinson’s Disease with sleep symptoms

Motivation: The role of the dorsal raphe nucleus (DRN) in sleep related pathologies in Parkinson’s disease (PD) remains under investigated. Goal(s): To characterize functional connectivity patterns and correlational structural tractography changes specific to the DRN in PD and sleep-related symptoms. Approach: Resting-state functional MRI and diffusion spectrum MRI metrics were compared across PD patients and healthy controls experiencing severe sleep disturbances. Results: We found changes in functional connectivity profiles of the DRN and findings suggesting axonal damage that showed stronger correlation with sleep symptoms in healthy controls compared to patients, implying potentially distinct pathophysiological mechanisms in symptom development. Impact: Clarifying involvement of the dorsal raphe nucleus and serotonergic pathways in the pathogenesis of sleep symptoms in Parkinson’s Disease may contribute to development of novel therapies targeted toward specific dysfunctional pathways involved in this quality-of-life disturbing condition.