Research Description

Apathy and Autonomic Functioning in Parkinson's Disease

Apathy is a proiminent neuropsychiatric feature of Parkinson’s disease involving a primary loss of motivation, interest, and effortful behavior. It is distinct from depression (Kirsch-Darrow et al., 2006), is associated with dementia, but nevertheless occurs in approximately 30% of nondemented PD patients. To date, there is little understanding of the mechanisms underlying apathy, though it has been associated with dysfunction of mesial frontal lobe systems.

A recent study from Dr. Bowers’ laboratory found a strong relationship between severity of apathy symptoms and skin conductance responses to emotional pictures. Skin conductance response is an autonomic measure of arousal. Autonomic symptoms occur in most patients with Parkinson’s disease at various stages of their illness. The domain of autonomic function is broad, and includes symptoms relating to cardiovascular, gastrointestinal, urinary, thermoregulatory, pupillomotor, and sexual functioning (Verbaan et al., 2007). Neuropathological studies of Parkinson’s disease have shown changes in brain and spinal cord regions that regulate autonomic functioning, such as the hypothalamus, sympathetic and parasympathetic systems, and the neural plexi of the pelvis, heart and gut (Micieli et al., 2003 Jost et al., 2003). Furthermore, it has been shown that more severe autonomic symptoms are associated with greater impairments in other domains of Parkinson’s disease including motor function, cognitive and psychiatric complications (Verbaan et al., 2007).

The goal of this project is to assess the relationship between apathy and autonomic symptoms in patients with idiopathic Parkinson’s disease. I will study between 75-100 patients with idiopathic Parkinson’s disease, and assess them on questionnaire measures of apathy and autonomic functioning. The primary hypothesis is that severity of apathy symptoms in PD will be associated with increased severity of reported autonomic symptoms.

To test this hypothesis I hope to evaluate between 75 and 100 patients with idiopathic Parkinson’s disease who are seen through the UF Movement Disorders Center. Patients will be recruited during their routine medical appointments. After signing an IRB-approved informed consent, participants will complete two self-report autonomic questionnaires: 1) the Scales for Outcomes in Parkinson’s Disease Autonomic Subsection (SCOPA-AUT) and 2) the Nonmotor Symptom Questionnaire (NMSQ). Additionally, scores on three mood measures will also be obtained including the Apathy Evaluation Scale (AES), the Beck Depression Inventory (BDI), and the State-Trait Anxiety Inventory.

I will analyze the results in several ways. We plan to look at correlations between total scores on the autonomic questionnaires and the mood measures. We will also divide participants into low and high apathy groups to see if there are differences in occurrence or severity of self-reported autonomic symptoms. We will also look at different systems (cardiovascular, sweating, gastrointestinal) on the autonomic questionnaires to see if certain symptom clusters are associated with apathy or depression. Finally, we will examine the influence of demographic and disease characteristics (i.e., duration of PD, severity of PD symptoms) on self-reported autonomic symptoms. Text