Stress system and related biomarkers in Parkinson's disease.

Parkinson's disease (PD) is characterized by complex motor and non-motor symptoms that vary in onset, severity, response to treatment, and disability. The unpredictable and debilitating nature of PD and the inability to halt or slow disease progression may result in distress. Stress may exacerbate biological mechanisms believed to contribute to neuronal loss in PD and lead to increased symptoms and poorer outcomes. The purpose of this chapter is to summarize and appraise animal and human research studies focused on stress-related biological mechanisms in PD, and to examine the relationship between stress and a variety of genetic, clinical and biochemical aspects of this debilitating disease.