The overall goal of this proposal is to further knowledge about non-motor symptoms in Parkinson's disease (PD). Specifically, our goal is to further understanding about apathy/loss of motivation symptoms. Apathy refers to deficit symptoms such as flattened emotions, loss of motivation, loss of interest, and loss of productive behavior. Recent studies have documented a high prevalence of apathy in PD (ex. 38-51%) and suggested that apathy may be distinct from depression. A preliminary study found that apathy occurred in the absence of depression in 29% of our PD sample (Kirsch-Darrow et al., 2006). Exploring whether these two mood presentations are separable may lead to better understanding of underlying causes, correlates, and consequences of emotional symptoms in neurologic disease. The specific aims of this NRSA are: (1) to learn whether apathy and depression can be distinguished using theory-guided confirmatory factor analysis and (2) to determine whether apathy affects neurocognitive performance in PD patients. We wish to examine the relationship between apathy symptoms, depression symptoms, and performance on multiple cognitive domains in non-demented PD patients. The findings from this research will aid public health by improving our understanding of some of the mood disorders experienced by patients with Parkinson's disease. This study proposes to examine differences between apathy and depression as well as how apathy affects thinking abilities. As both apathy and depression can complicate the treatment of PD and reduce related quality of life for patients, better understanding will lead to improved recognition and treatment of mood disorders in PD. [unreadable] [unreadable] [unreadable]