Mood-Motor Interactions in Parkinson's Disease: A Scoping Review of Clinical Correlates and Neurobiological Mechanisms

Parkinson’s disease (PD) is characterized not only by motor symptoms such as bradykinesia, rigidity, tremor, and postural instability but also by high rates of mood disturbances, including depression, anxiety, and other affective symptoms. Emerging evidence suggests that mood and motor symptoms in PD are closely interconnected through shared neurobiological mechanisms, yet these interactions remain incompletely understood. This scoping review aims to systematically map the literature on the clinical and neurobiological correlates of mood-motor interactions in adults with PD, synthesizing evidence across neurotransmitter systems, neural circuits, neuroimaging markers, neuroinflammation, the HPA axis, and gut-brain pathways.