Clinical Trials for Depression, Anxiety, Fatigue, and Apathy in Parkinson’s Disease

Abstract

Depression, anxiety, apathy, and fatigue are common manifestations of Parkinson’s disease with a significant impact on quality of life and everyday functioning of patients. Despite their clinical relevance, only limited evidence is available regarding treatment interventions for these disorders, and properly designed trials with depression, anxiety, apathy, and fatigue as primary outcome measures have been scarce to this date. All of these disorders present multidimensional constructs with differing underlying neurobiological basis, which will likely necessitate development of distinct therapeutic approaches. This chapter will discuss the terminology and definition of depression, anxiety, apathy, and fatigue in PD, their differentiation from other PD- and non–PD-related symptoms, subtyping, physiological markers, as well as considerations related to the optimal outcome measures and design of clinical trials.